RFC FS-1033: Deprecate places where `seq` can be omitted (#17772)

* Treat `{ 1..10 }` as sequence expression

* deprecate { start..finish } and { start..step..finish }

* fix build part1

* 3873., chkDeprecatePlacesWhereSeqCanBeOmitted

* more tests

* release notes

* reorg seq tests

* Better check

* fix merge conflicts

* Add code fix for adding missing `seq` before `{…}`

* More tests

* Fmt

* update release notes

* more editor tests

---------

Co-authored-by: Brian Rourke Boll <brianrourkeboll@gmail.com>

docs/release-notes/.FSharp.Compiler.Service/9.0.200.md

@@ -8,7 +8,7 @@
 * Fix nullness inference for member val and other OO scenarios  ([PR #17845](https://github.com/dotnet/fsharp/pull/17845))
 
 ### Added
-
+* Deprecate places where `seq` can be omitted. ([Language suggestion #1033](https://github.com/fsharp/fslang-suggestions/issues/1033), [PR #17772](https://github.com/dotnet/fsharp/pull/17772))
 * Support literal attribute on decimals ([PR #17769](https://github.com/dotnet/fsharp/pull/17769))
 
 ### Changed

docs/release-notes/.Language/preview.md

@@ -1,6 +1,7 @@
 ### Added
 
 * Better generic unmanaged structs handling. ([Language suggestion #692](https://github.com/fsharp/fslang-suggestions/issues/692), [PR #12154](https://github.com/dotnet/fsharp/pull/12154))
+* Deprecate places where `seq` can be omitted. ([Language suggestion #1033](https://github.com/fsharp/fslang-suggestions/issues/1033), [PR #17772](https://github.com/dotnet/fsharp/pull/17772))
 
 ### Fixed
 

docs/release-notes/.VisualStudio/17.13.md

@@ -0,0 +1,8 @@
+### Fixed
+
+### Added
+* Code fix for adding missing `seq`. ([PR #17772](https://github.com/dotnet/fsharp/pull/17772))
+
+### Changed
+
+### Breaking Changes

src/Compiler/Checking/Expressions/CheckExpressions.fs

@@ -5891,6 +5891,17 @@ and TcExprUndelayed (cenv: cenv) (overallTy: OverallTy) env tpenv (synExpr: SynE
         TcForEachExpr cenv overallTy env tpenv (seqExprOnly, isFromSource, pat, synEnumExpr, synBodyExpr, m, spFor, spIn, m)
 
     | SynExpr.ComputationExpr (hasSeqBuilder, comp, m) ->
+        let isIndexRange = match comp with | SynExpr.IndexRange _ -> true | _ -> false
+        let deprecatedPlacesWhereSeqCanBeOmitted =
+            cenv.g.langVersion.SupportsFeature LanguageFeature.DeprecatePlacesWhereSeqCanBeOmitted
+        if
+            deprecatedPlacesWhereSeqCanBeOmitted
+            && isIndexRange
+            && not hasSeqBuilder
+            && not cenv.g.compilingFSharpCore
+        then
+            warning (Error(FSComp.SR.chkDeprecatePlacesWhereSeqCanBeOmitted (), m))
+
         let env = ExitFamilyRegion env
         cenv.TcSequenceExpressionEntry cenv env overallTy tpenv (hasSeqBuilder, comp) m
 

src/Compiler/FSComp.txt

@@ -1783,4 +1783,6 @@ featureEmptyBodiedComputationExpressions,"Support for computation expressions wi
 featureAllowAccessModifiersToAutoPropertiesGettersAndSetters,"Allow access modifiers to auto properties getters and setters"
 3871,tcAccessModifiersNotAllowedInSRTPConstraint,"Access modifiers cannot be applied to an SRTP constraint."
 featureAllowObjectExpressionWithoutOverrides,"Allow object expressions without overrides"
-3872,tcPartialActivePattern,"Multi-case partial active patterns are not supported. Consider using a single-case partial active pattern or a full active pattern."
+3872,tcPartialActivePattern,"Multi-case partial active patterns are not supported. Consider using a single-case partial active pattern or a full active pattern."
+3873,chkDeprecatePlacesWhereSeqCanBeOmitted,"This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'"
+featureDeprecatePlacesWhereSeqCanBeOmitted,"Deprecate places where 'seq' can be omitted"

src/Compiler/Facilities/LanguageFeatures.fs

@@ -94,6 +94,7 @@ type LanguageFeature =
     | ParsedHashDirectiveArgumentNonQuotes
     | EmptyBodiedComputationExpressions
     | AllowObjectExpressionWithoutOverrides
+    | DeprecatePlacesWhereSeqCanBeOmitted
 
 /// LanguageVersion management
 type LanguageVersion(versionText) =
@@ -219,6 +220,7 @@ type LanguageVersion(versionText) =
                 LanguageFeature.FromEndSlicing, previewVersion // Unfinished features --- needs work
                 LanguageFeature.AllowAccessModifiersToAutoPropertiesGettersAndSetters, previewVersion
                 LanguageFeature.AllowObjectExpressionWithoutOverrides, previewVersion
+                LanguageFeature.DeprecatePlacesWhereSeqCanBeOmitted, previewVersion
             ]
 
     static let defaultLanguageVersion = LanguageVersion("default")
@@ -375,6 +377,7 @@ type LanguageVersion(versionText) =
         | LanguageFeature.ParsedHashDirectiveArgumentNonQuotes -> FSComp.SR.featureParsedHashDirectiveArgumentNonString ()
         | LanguageFeature.EmptyBodiedComputationExpressions -> FSComp.SR.featureEmptyBodiedComputationExpressions ()
         | LanguageFeature.AllowObjectExpressionWithoutOverrides -> FSComp.SR.featureAllowObjectExpressionWithoutOverrides ()
+        | LanguageFeature.DeprecatePlacesWhereSeqCanBeOmitted -> FSComp.SR.featureDeprecatePlacesWhereSeqCanBeOmitted ()
 
     /// Get a version string associated with the given feature.
     static member GetFeatureVersionString feature =

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -85,6 +85,7 @@ type LanguageFeature =
     | ParsedHashDirectiveArgumentNonQuotes
     | EmptyBodiedComputationExpressions
     | AllowObjectExpressionWithoutOverrides
+    | DeprecatePlacesWhereSeqCanBeOmitted
 
 /// LanguageVersion management
 type LanguageVersion =

src/Compiler/xlf/FSComp.txt.cs.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Tento výraz je anonymní záznam, použijte {{|...|}} místo {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Duplicitní parametr Parametr {0} byl v této metodě použit vícekrát.</target>
@@ -322,6 +327,11 @@
         <target state="translated">opravit překlad názvů typů delegátů, viz https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">vzor discard ve vazbě použití</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Neplatný výraz záznamu, pořadí nebo výpočtu. Výrazy pořadí by měly mít notaci seq {{ ... }}.</target>
+        <target state="needs-review-translation">Neplatný výraz záznamu, pořadí nebo výpočtu. Výrazy pořadí by měly mít notaci seq {{ ... }}.</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.de.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Dieser Ausdruck ist ein anonymer Datensatz. Verwenden Sie {{|...|}} anstelle von {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Doppelter Parameter. Der Parameter „{0}“ wurde in dieser Methode mehrmals verwendet.</target>
@@ -322,6 +327,11 @@
         <target state="translated">Informationen zur Problembehebung bezüglich der Auflösung von Delegattypnamen finden Sie unter https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">Das Verwerfen des verwendeten Musters ist verbindlich.</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Ungültiger Datensatz-, Sequenz- oder Berechnungsausdruck. Sequenzausdrücke müssen das Format "seq {{ ... }}" besitzen.</target>
+        <target state="needs-review-translation">Ungültiger Datensatz-, Sequenz- oder Berechnungsausdruck. Sequenzausdrücke müssen das Format "seq {{ ... }}" besitzen.</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.es.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Esta expresión es un registro anónimo; use {{|...|}} en lugar de {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Parámetro duplicado. El parámetro '{0}' se ha usado más una vez en este método.</target>
@@ -322,6 +327,11 @@
         <target state="translated">corrección para la resolución de nombres de tipo de delegado, consulte https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">descartar enlace de patrón en uso</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Expresión de registro, secuencia o cómputo no válida. Las expresiones de secuencia deben tener el formato 'seq {{ ... }}'.</target>
+        <target state="needs-review-translation">Expresión de registro, secuencia o cómputo no válida. Las expresiones de secuencia deben tener el formato 'seq {{ ... }}'.</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.fr.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Cette expression est un enregistrement anonyme, utilisez {{|...|}} au lieu de {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Paramètre dupliqué. Le paramètre « {0} » a été utilisé une fois de plus dans cette méthode.</target>
@@ -322,6 +327,11 @@
         <target state="translated">corriger pour résoudre les noms de types délégués, voir https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">annuler le modèle dans la liaison d’utilisation</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Expression d'enregistrement, de séquence ou de calcul non valide. Les expressions de séquence doivent avoir le format 'seq {{ ... }}'</target>
+        <target state="needs-review-translation">Expression d'enregistrement, de séquence ou de calcul non valide. Les expressions de séquence doivent avoir le format 'seq {{ ... }}'</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.it.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Questa espressione è un record anonimo. Usa {{|...|}} invece di {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Parametro duplicato. Il parametro '{0}' è stato utilizzato più volte in questo metodo.</target>
@@ -322,6 +327,11 @@
         <target state="translated">correggere la risoluzione dei nomi dei tipi delegati, vedere https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">rimuovi criterio nell'utilizzo dell'associazione</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Espressione di calcolo, sequenza o record non valida. Il formato delle espressioni sequenza deve essere 'seq {{ ... }}'</target>
+        <target state="needs-review-translation">Espressione di calcolo, sequenza o record non valida. Il formato delle espressioni sequenza deve essere 'seq {{ ... }}'</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.ja.xlf

@@ -52,6 +52,11 @@
         <target state="translated">この式は匿名レコードであり、{{...}} の代わりに {{|...|}} を使用してください。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">パラメーターが重複しています。パラメーター '{0}' は、このメソッドで 1 回以上使用されています。</target>
@@ -322,6 +327,11 @@
         <target state="translated">デリゲート型名の解決を修正するには、https://github.com/dotnet/fsharp/issues/10228 を参照してください</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">使用バインドでパターンを破棄する</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">無効なレコード、シーケンス式、またはコンピュテーション式です。シーケンス式は 'seq {{ ... }}' という形式にしてください。</target>
+        <target state="needs-review-translation">無効なレコード、シーケンス式、またはコンピュテーション式です。シーケンス式は 'seq {{ ... }}' という形式にしてください。</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.ko.xlf

@@ -52,6 +52,11 @@
         <target state="translated">이 식은 익명 레코드입니다. {{...}} 대신 {{|...|}}을 사용하세요.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">매개 변수가 중복되었습니다. 이 메소드에서 매개 변수 '{0}'이(가) 두 번 이상 사용되었습니다.</target>
@@ -322,6 +327,11 @@
         <target state="translated">대리자 형식 이름의 해결 방법을 수정합니다. https://github.com/dotnet/fsharp/issues/10228 참조하세요.</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">사용 중인 패턴 바인딩 무시</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">레코드, 시퀀스 또는 계산 식이 잘못되었습니다. 시퀀스 식의 형식은 'seq {{ ... }}'여야 합니다.</target>
+        <target state="needs-review-translation">레코드, 시퀀스 또는 계산 식이 잘못되었습니다. 시퀀스 식의 형식은 'seq {{ ... }}'여야 합니다.</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.pl.xlf

@@ -52,6 +52,11 @@
         <target state="translated">To wyrażenie jest rekordem anonimowym. Użyj {{|...|}} zamiast {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Zduplikowany parametr. Parametr „{0}” został użyty więcej niż raz w tej metodzie.</target>
@@ -322,6 +327,11 @@
         <target state="translated">naprawa rozpoznawania nazw typów delegatów, sprawdź stronę https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">odrzuć wzorzec w powiązaniu użycia</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Nieprawidłowe wyrażenie rekordu, sekwencji lub obliczenia. Wyrażenia sekwencji powinny mieć postać „seq {{ ... }}”</target>
+        <target state="needs-review-translation">Nieprawidłowe wyrażenie rekordu, sekwencji lub obliczenia. Wyrażenia sekwencji powinny mieć postać „seq {{ ... }}”</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.pt-BR.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Esta expressão é um registro anônimo, use {{|...|}} em vez de {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Parâmetro duplicado. O parâmetro '{0}' foi usado mais de uma vez neste método.</target>
@@ -322,6 +327,11 @@
         <target state="translated">corrigir para resolução de nomes de tipos delegados, consulte https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">descartar o padrão em uso de associação</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Expressão de registro, sequência ou computação inválida. Expressões de sequência devem estar na forma 'seq {{ ... }}'</target>
+        <target state="needs-review-translation">Expressão de registro, sequência ou computação inválida. Expressões de sequência devem estar na forma 'seq {{ ... }}'</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.ru.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Это выражение является анонимной записью. Используйте {{|...|}} вместо {{...}}.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Повторяющийся параметр. Параметр "{0}" использовался в этом методе несколько раз.</target>
@@ -322,6 +327,11 @@
         <target state="translated">исправить разрешение имен типов делегатов, см. https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">шаблон отмены в привязке использования</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Недопустимая запись, выражение последовательности или вычислительное выражение. Выражения последовательностей должны иметь форму "seq {{ ... }}'</target>
+        <target state="needs-review-translation">Недопустимая запись, выражение последовательности или вычислительное выражение. Выражения последовательностей должны иметь форму "seq {{ ... }}'</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.tr.xlf

@@ -52,6 +52,11 @@
         <target state="translated">Bu ifade, anonim bir kayıt, {{...}} yerine {{|...|}} kullanın.</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">Yinelenen parametre. '{0}' parametresi bu metotta bir kereden fazla kullanıldı.</target>
@@ -322,6 +327,11 @@
         <target state="translated">temsilci türü adlarının çözümlenmesiyle ilgili sorunun çözümü için bkz. https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">kullanım bağlamasında deseni at</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">Geçersiz kayıt, dizi veya hesaplama ifadesi. Dizi ifadeleri 'seq {{ ... }}' biçiminde olmalıdır</target>
+        <target state="needs-review-translation">Geçersiz kayıt, dizi veya hesaplama ifadesi. Dizi ifadeleri 'seq {{ ... }}' biçiminde olmalıdır</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.zh-Hans.xlf

@@ -52,6 +52,11 @@
         <target state="translated">此表达式是匿名记录，请使用 {{|...|}} 而不是 {{...}}。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">参数重复。此方法中多次使用了参数“{0}”。</target>
@@ -322,6 +327,11 @@
         <target state="translated">修复了委托类型名称的解析，请参阅 https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">放弃使用绑定模式</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">记录、序列或计算表达式无效。序列表达式的格式应为“seq {{ ... }}”</target>
+        <target state="needs-review-translation">记录、序列或计算表达式无效。序列表达式的格式应为“seq {{ ... }}”</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

src/Compiler/xlf/FSComp.txt.zh-Hant.xlf

@@ -52,6 +52,11 @@
         <target state="translated">此運算式是匿名記錄，請使用 {{|...|}} 而不是 {{...}}。</target>
         <note />
       </trans-unit>
+      <trans-unit id="chkDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</source>
+        <target state="new">This construct is deprecated. Sequence expressions should be of the form 'seq {{ ... }}'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="chkDuplicatedMethodParameter">
         <source>Duplicate parameter. The parameter '{0}' has been used more that once in this method.</source>
         <target state="translated">重複的參數。參數 '{0}' 在此方法中使用多次。</target>
@@ -322,6 +327,11 @@
         <target state="translated">修正委派類型名稱的解析，請參閱 https://github.com/dotnet/fsharp/issues/10228</target>
         <note />
       </trans-unit>
+      <trans-unit id="featureDeprecatePlacesWhereSeqCanBeOmitted">
+        <source>Deprecate places where 'seq' can be omitted</source>
+        <target state="new">Deprecate places where 'seq' can be omitted</target>
+        <note />
+      </trans-unit>
       <trans-unit id="featureDiscardUseValue">
         <source>discard pattern in use binding</source>
         <target state="translated">捨棄使用繫結中的模式</target>
@@ -4524,7 +4534,7 @@
       </trans-unit>
       <trans-unit id="tcInvalidSequenceExpressionSyntaxForm">
         <source>Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq {{ ... }}'</source>
-        <target state="translated">無效的記錄、循序項或計算運算式。循序項運算式應該是 'seq {{ ... }}' 形式。</target>
+        <target state="needs-review-translation">無效的記錄、循序項或計算運算式。循序項運算式應該是 'seq {{ ... }}' 形式。</target>
         <note />
       </trans-unit>
       <trans-unit id="tcExpressionWithIfRequiresParenthesis">

tests/FSharp.Compiler.ComponentTests/FSharp.Compiler.ComponentTests.fsproj

@@ -223,6 +223,7 @@
     <Compile Include="Language\RegressionTests.fs" />
     <Compile Include="Language\AttributeCheckingTests.fs" />
     <Compile Include="Language\ObsoleteAttributeCheckingTests.fs" />
+    <Compile Include="Language\SequenceExpressions\SequenceExpressionTests.fs" />
     <Compile Include="Language\XmlComments.fs" />
     <Compile Include="Language\CompilerDirectiveTests.fs" />
     <Compile Include="Language\CodeQuotationTests.fs" />
@@ -237,7 +238,6 @@
     <Compile Include="Language\FixedBindings\FixedBindings.fs" />
     <Compile Include="Language\ExtensionMethodTests.fs" />
     <Compile Include="Language\WhileBangTests.fs" />
-    <Compile Include="Language\SequenceExpressionTests.fs" />
     <Compile Include="Language\StaticClassTests.fs" />
     <Compile Include="Language\PrintfFormatTests.fs" />
     <Compile Include="Language\InterfaceTests.fs" />

tests/FSharp.Compiler.ComponentTests/Language/SequenceExpressions/E_SequenceExpressions01.fs

@@ -0,0 +1,76 @@
+{ 1..10 }
+
+{ 1..5..10 }
+
+[| { 1..10 } |]
+
+[| { 1..5..10 } |]
+
+let a = { 1..10 }
+
+let a3 = { 1..10..20 }
+
+let b = [| { 1..10 } |]
+
+let b3 = [| { 1..10..20 } |]
+
+let c = [ { 1..10 } ]
+
+[| { 1..10 } |]
+
+[| yield { 1..10 } |]
+
+[ { 1..10 } ]
+
+[ { 1..10..10 } ]
+
+[ yield { 1..10 } ]
+
+[ yield { 1..10..20 } ]
+
+ResizeArray({ 1..10 })
+
+ResizeArray({ 1..10..20 })
+
+let fw start finish = [ for x in { start..finish } -> x ]
+
+let fe start finish = [| for x in { start..finish } -> x |]
+
+for x in { 1..10 }  do ()
+
+for x in { 1..5..10 } do ()
+    
+let f = Seq.head
+
+let a2 = f { 1..6 }
+
+let a23 = f { 1..6..10 }
+
+let b2 = set { 1..6 }
+
+let f10 start finish = for x in { start..finish } do ignore (float x ** float x)
+
+let (..) _ _ = "lol"
+
+let lol1 = { 1..10 }
+
+{ 1..5..10 }
+
+let resultInt = Seq.length {1..8}
+
+let resultInt2 funcInt  = Seq.map3 funcInt { 1..8 } { 2..9 } { 3..10 }
+
+let verify c = failwith "not implemented"
+
+Seq.splitInto 4 {1..5} |> verify { 1.. 10 }
+
+seq [ {1..4}; {5..7}; {8..10} ]
+
+Seq.allPairs { 1..7 } Seq.empty
+
+Seq.allPairs Seq.empty { 1..7 }
+
+let intArr1 = [| yield! {1..100}
+                 yield! {1..100} |]
+
+Array.ofSeq {1..10}

tests/FSharp.Compiler.ComponentTests/Language/SequenceExpressions/SequenceExpressionTests.fs

@@ -1,7 +1,8 @@
 // Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
 
-module Language.SequenceExpressionTests
+module Language.SequenceExpression.SequenceExpressionTests
 
+open FSharp.Test
 open Xunit
 open FSharp.Test.Compiler
 open FSharp.Test.ScriptHelpers
@@ -467,4 +468,125 @@ let f2 = return! [ 3; 4 ]
     |> withDiagnostics [
         (Error 748, Line 2, Col 10, Line 2, Col 16, "This construct may only be used within computation expressions. To return a value from an ordinary function simply write the expression without 'return'.");
         (Error 748, Line 3, Col 10, Line 3, Col 17, "This construct may only be used within computation expressions. To return a value from an ordinary function simply write the expression without 'return'.")
-    ]
+    ]
+
+[<Fact>]
+let ``Sequence(SynExpr.Sequential) expressions should be of the form 'seq { ... } lang version 9``() =
+    Fsx """
+{ 1;10 }
+[| { 1;10 } |]
+let a = { 1;10 }
+let b = [| { 1;10 } |]
+let c = [ { 1;10 } ]
+    """
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersion90
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics [
+        (Error 740, Line 2, Col 1, Line 2, Col 9, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 3, Col 4, Line 3, Col 12, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 4, Col 9, Line 4, Col 17, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 5, Col 12, Line 5, Col 20, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 6, Col 11, Line 6, Col 19, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+    ]
+    
+[<Fact>]
+let ``Sequence(SynExpr.Sequential) expressions should be of the form 'seq { ... } lang version preview``() =
+    Fsx """
+{ 1;10 }
+[| { 1;10 } |]
+let a = { 1;10 }
+let b = [| { 1;10 } |]
+let c = [ { 1;10 } ]
+    """
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersionPreview
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics [
+        (Error 740, Line 2, Col 1, Line 2, Col 9, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 3, Col 4, Line 3, Col 12, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 4, Col 9, Line 4, Col 17, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 5, Col 12, Line 5, Col 20, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+        (Error 740, Line 6, Col 11, Line 6, Col 19, "Invalid record, sequence or computation expression. Sequence expressions should be of the form 'seq { ... }'")
+    ]
+
+// SOURCE=E_SequenceExpressions01.fs 	# E_SequenceExpressions01.fs
+[<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"E_SequenceExpressions01.fs"|])>]
+let ``E_SequenceExpressions01 lang version 9`` compilation =
+    compilation
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersion90
+    |> typecheck
+    |> shouldSucceed
+
+// SOURCE=E_SequenceExpressions01.fs 	# E_SequenceExpressions01.fs
+[<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"E_SequenceExpressions01.fs"|])>]
+let ``E_SequenceExpressions01 lang version preview`` compilation =
+    compilation
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersionPreview
+    |> typecheck
+    |> shouldFail
+    |> withDiagnostics [
+        (Warning 3873, Line 1, Col 1, Line 1, Col 10, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 3, Col 1, Line 3, Col 13, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 5, Col 4, Line 5, Col 13, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 7, Col 4, Line 7, Col 16, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 9, Col 9, Line 9, Col 18, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 11, Col 10, Line 11, Col 23, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 13, Col 12, Line 13, Col 21, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 15, Col 13, Line 15, Col 26, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 17, Col 11, Line 17, Col 20, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 19, Col 4, Line 19, Col 13, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 21, Col 10, Line 21, Col 19, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 23, Col 3, Line 23, Col 12, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 25, Col 3, Line 25, Col 16, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 27, Col 9, Line 27, Col 18, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 29, Col 9, Line 29, Col 22, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 31, Col 13, Line 31, Col 22, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 33, Col 13, Line 33, Col 26, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 35, Col 34, Line 35, Col 51, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 37, Col 35, Line 37, Col 52, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 39, Col 10, Line 39, Col 19, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 41, Col 10, Line 41, Col 22, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 45, Col 12, Line 45, Col 20, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 47, Col 13, Line 47, Col 25, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 49, Col 14, Line 49, Col 22, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 51, Col 33, Line 51, Col 50, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 55, Col 12, Line 55, Col 21, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 57, Col 1, Line 57, Col 13, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 59, Col 28, Line 59, Col 34, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 61, Col 44, Line 61, Col 52, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 61, Col 53, Line 61, Col 61, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 61, Col 62, Line 61, Col 71, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 65, Col 17, Line 65, Col 23, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 65, Col 34, Line 65, Col 44, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 67, Col 7, Line 67, Col 13, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 67, Col 15, Line 67, Col 21, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 67, Col 23, Line 67, Col 30, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 69, Col 14, Line 69, Col 22, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 71, Col 24, Line 71, Col 32, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 73, Col 25, Line 73, Col 33, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 74, Col 25, Line 74, Col 33, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+        (Warning 3873, Line 76, Col 13, Line 76, Col 20, "This construct is deprecated. Sequence expressions should be of the form 'seq { ... }'")
+    ]
+
+// SOURCE=SequenceExpressions01.fs 	# SequenceExpressions01.fs
+[<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"SequenceExpressions01.fs"|])>]
+let ``SequenceExpressions01 lang version 9`` compilation =
+    compilation
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersion90
+    |> typecheck
+    |> shouldSucceed
+    
+// SOURCE=SequenceExpressions01.fs 	# SequenceExpressions01.fs
+[<Theory; Directory(__SOURCE_DIRECTORY__, Includes=[|"SequenceExpressions01.fs"|])>]
+let ``SequenceExpressions01 lang version preview`` compilation =
+    compilation
+    |> withOptions [ "--nowarn:0020" ]
+    |> withLangVersionPreview
+    |> typecheck
+    |> shouldSucceed

tests/FSharp.Compiler.ComponentTests/Language/SequenceExpressions/SequenceExpressions01.fs

@@ -0,0 +1,76 @@
+seq { 1..10 }
+
+seq { 1..5..10 }
+
+[| seq { 1..10 } |]
+
+[| seq { 1..5..10 } |]
+
+let a = seq { 1..10 }
+
+let a3 = seq { 1..10..20 }
+
+let b = [| seq { 1..10 } |]
+
+let b3 = [| seq { 1..10..20 } |]
+
+let c = [ seq { 1..10 } ]
+
+[| seq { 1..10 } |]
+
+[| yield seq { 1..10 } |]
+
+[ seq { 1..10 } ]
+
+[ seq { 1..10..10 } ]
+
+[ yield seq { 1..10 } ]
+
+[ yield seq { 1..10..20 } ]
+
+ResizeArray(seq { 1..10 })
+
+ResizeArray(seq { 1..10..20 })
+
+let fw start finish = [ for x in seq { start..finish } -> x ]
+
+let fe start finish = [| for x in seq { start..finish } -> x |]
+
+for x in seq { 1..10 }  do ()
+
+for x in seq { 1..5..10 } do ()
+    
+let f = Seq.head
+
+let a2 = f (seq { 1..6 })
+
+let a23 = f (seq { 1..6..10 })
+
+let b2 = set (seq { 1..6 })
+
+let f10 start finish = for x in seq { start..finish } do ignore (float x ** float x)
+
+let (..) _ _ = "lol"
+
+let lol1 = seq { 1..10 }
+
+seq { 1..5..10 }
+
+let resultInt = Seq.length (seq {1..8})
+
+let resultInt2 funcInt  = Seq.map3 funcInt (seq { 1..8 }) (seq { 2..9 }) (seq { 3..10 })
+
+let verify c = failwith "not implemented"
+
+Seq.splitInto 4 (seq {1..5}) |> verify (seq { 1.. 10 })
+
+seq [ seq {1..4}; seq {5..7}; seq {8..10} ]
+
+Seq.allPairs (seq { 1..7 }) Seq.empty
+
+Seq.allPairs Seq.empty (seq { 1..7 })
+
+let intArr1 = [| yield! seq {1..100}
+                 yield! seq {1..100} |]
+
+Array.ofSeq (seq {1..10})

tests/FSharp.Compiler.Service.Tests/PatternMatchCompilationTests.fs

@@ -455,7 +455,7 @@ let r as _ = 10
 let s as Id0 = 11
 let t as (u) = 12
 let v as struct(w, x) = 13, 14
-let y as z : int = 15{set { 'a'..'x' } - set [ 'p'; 'v' ] |> Set.map (sprintf " + %c") |> System.String.Concat}
+let y as z : int = 15{set (seq { 'a'..'x' }) - set [ 'p'; 'v' ] |> Set.map (sprintf " + %c") |> System.String.Concat}
 Some p |> eq<AAA>
 Some v |> eq<struct(int * int)>
 ()
@@ -590,7 +590,7 @@ let _ as r = 10
 let Id0 as s = 11
 let (t) as u = 12
 let struct(w, v) as x = 13, 14
-let (y : int) as z = 15{set { 'a'..'v' } - set [ 'h'; 'q' ] |> Set.map (sprintf " + %c") |> System.String.Concat}
+let (y : int) as z = 15{set (seq { 'a'..'v' }) - set [ 'h'; 'q' ] |> Set.map (sprintf " + %c") |> System.String.Concat}
 Some h |> eq<int * int>
 Some q |> eq<AAA>
 Some x |> eq<struct(int * int)>
@@ -917,7 +917,7 @@ let :? z as
 
 [<FactForNETCOREAPP>]
 let ``As 16 - syntactical precedence matrix testing left with type tests - total patterns`` () =
-    let validSet = set { 'a'..'x' } - set [ 'p'; 'q' ] |> Set.map string
+    let validSet = set (seq { 'a'..'x' }) - set [ 'p'; 'q' ] |> Set.map string
     let _, checkResults = getParseAndCheckResults70 $"""
 let eq<'T> (x:'T option) = () // FS-1093-safe type assert function
 let (|Id0|) = ignore

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule.fs

@@ -259,8 +259,8 @@ type ArrayModule() =
     [<Fact>]
     member _.Except() =
         // integer array
-        let intArr1 = [| yield! {1..100}
+        let intArr1 = [| yield! seq {1..100}
-                         yield! {1..100} |]
+                         yield! seq {1..100} |]
         let intArr2 = [| 1 .. 10 |]
         let expectedIntArr = [| 11 .. 100 |]
 

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ArrayModule2.fs

@@ -372,7 +372,7 @@ type ArrayModule2() =
     [<Fact>]
     member this.Of_Seq() =
         // integer array  
-        let resultInt = Array.ofSeq {1..10}
+        let resultInt = Array.ofSeq (seq {1..10})
         if resultInt <> [|1..10|] then Assert.Fail()
         
         // string array    

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ListModule.fs

@@ -346,8 +346,8 @@ type ListModule() =
     [<Fact>]
     member _.Except() =
         // integer list
-        let intList1 = [ yield! {1..100}
+        let intList1 = [ yield! seq {1..100}
-                         yield! {1..100} ]
+                         yield! seq {1..100} ]
         let intList2 = [1..10]
         let expectedIntList = [11..100]
 

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ListModule2.fs

@@ -367,7 +367,7 @@ type ListModule02() =
     [<Fact>]
     member this.Of_Seq() =
         // integer List  
-        let resultInt = List.ofSeq {1..10}        
+        let resultInt = List.ofSeq (seq {1..10})        
         Assert.AreEqual([1..10], resultInt)
         
         // string List    

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/ObsoleteSeqFunctions.fs

@@ -15,14 +15,14 @@ type ObsoleteSeqFunctions() =
 
         // Negative index
         for i = -1 downto -10 do
-           CheckThrowsArgumentException (fun () -> Seq.nth i { 10 .. 20 } |> ignore)
+           CheckThrowsArgumentException (fun () -> Seq.nth i (seq { 10 .. 20 }) |> ignore)
 
         // Out of range
         for i = 11 to 20 do
-           CheckThrowsArgumentException (fun () -> Seq.nth i { 10 .. 20 } |> ignore)
+           CheckThrowsArgumentException (fun () -> Seq.nth i (seq { 10 .. 20 }) |> ignore)
 
          // integer Seq
-        let resultInt = Seq.nth 3 { 10..20 } 
+        let resultInt = Seq.nth 3 (seq { 10..20 }) 
         Assert.AreEqual(13, resultInt)
 
         // string Seq

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/SeqModule.fs

@@ -39,8 +39,8 @@ type SeqModule() =
 
         // empty Seq
         VerifySeqsEqual Seq.empty <| Seq.allPairs Seq.empty Seq.empty
-        VerifySeqsEqual Seq.empty <| Seq.allPairs { 1..7 } Seq.empty
+        VerifySeqsEqual Seq.empty <| Seq.allPairs (seq { 1..7 }) Seq.empty
-        VerifySeqsEqual Seq.empty <| Seq.allPairs Seq.empty { 1..7 }
+        VerifySeqsEqual Seq.empty <| Seq.allPairs Seq.empty (seq { 1..7 })
 
         // null Seq
         CheckThrowsArgumentNullException(fun() -> Seq.allPairs null null |> ignore)
@@ -349,9 +349,9 @@ type SeqModule() =
             |> Seq.iter ((<||) VerifySeqsEqual)
 
         // int Seq
-        verify [[1..4];[5..8]] <| Seq.chunkBySize 4 {1..8}
+        verify [[1..4];[5..8]] <| Seq.chunkBySize 4 (seq {1..8})
-        verify [[1..4];[5..8];[9..10]] <| Seq.chunkBySize 4 {1..10}
+        verify [[1..4];[5..8];[9..10]] <| Seq.chunkBySize 4 (seq {1..10})
-        verify [[1]; [2]; [3]; [4]] <| Seq.chunkBySize 1 {1..4}
+        verify [[1]; [2]; [3]; [4]] <| Seq.chunkBySize 1 (seq {1..4})
 
         Seq.chunkBySize 2 (Seq.initInfinite id)
         |> Seq.take 3
@@ -372,8 +372,8 @@ type SeqModule() =
         CheckThrowsArgumentNullException (fun () -> Seq.chunkBySize 3 nullSeq |> ignore)
 
         // invalidArg
-        CheckThrowsArgumentException (fun () -> Seq.chunkBySize 0 {1..10} |> ignore)
+        CheckThrowsArgumentException (fun () -> Seq.chunkBySize 0 (seq {1..10}) |> ignore)
-        CheckThrowsArgumentException (fun () -> Seq.chunkBySize -1 {1..10} |> ignore)
+        CheckThrowsArgumentException (fun () -> Seq.chunkBySize -1 (seq {1..10}) |> ignore)
 
         ()
 
@@ -385,12 +385,12 @@ type SeqModule() =
             |> Seq.iter ((<||) VerifySeqsEqual)
 
         // int Seq
-        Seq.splitInto 3 {1..10} |> verify (seq [ {1..4}; {5..7}; {8..10} ])
+        Seq.splitInto 3 (seq {1..10}) |> verify (seq [ seq {1..4}; seq {5..7}; seq {8..10} ])
-        Seq.splitInto 3 {1..11} |> verify (seq [ {1..4}; {5..8}; {9..11} ])
+        Seq.splitInto 3 (seq {1..11}) |> verify (seq [ seq {1..4}; seq {5..8}; seq {9..11} ])
-        Seq.splitInto 3 {1..12} |> verify (seq [ {1..4}; {5..8}; {9..12} ])
+        Seq.splitInto 3 (seq {1..12}) |> verify (seq [ seq {1..4}; seq {5..8}; seq {9..12} ])
 
-        Seq.splitInto 4 {1..5} |> verify (seq [ [1..2]; [3]; [4]; [5] ])
+        Seq.splitInto 4 (seq {1..5}) |> verify (seq [ [1..2]; [3]; [4]; [5] ])
-        Seq.splitInto 20 {1..4} |> verify (seq [ [1]; [2]; [3]; [4] ])
+        Seq.splitInto 20 (seq {1..4}) |> verify (seq [ [1]; [2]; [3]; [4] ])
 
         // string Seq
         Seq.splitInto 3 ["a";"b";"c";"d";"e"] |> verify ([ ["a"; "b"]; ["c";"d"]; ["e"] ])
@@ -586,10 +586,10 @@ type SeqModule() =
     [<Fact>]
     member _.Except() =
         // integer Seq
-        let intSeq1 = seq { yield! {1..100}
+        let intSeq1 = seq { yield! seq {1..100}
-                            yield! {1..100} }
+                            yield! seq {1..100} }
-        let intSeq2 = {1..10}
+        let intSeq2 = seq {1..10}
-        let expectedIntSeq = {11..100}
+        let expectedIntSeq = seq {11..100}
 
         VerifySeqsEqual expectedIntSeq <| Seq.except intSeq2 intSeq1
 
@@ -609,7 +609,7 @@ type SeqModule() =
 
         // empty Seq
         let emptyIntSeq = Seq.empty<int>
-        VerifySeqsEqual {1..100} <| Seq.except emptyIntSeq intSeq1
+        VerifySeqsEqual (seq {1..100}) <| Seq.except emptyIntSeq intSeq1
         VerifySeqsEqual emptyIntSeq <| Seq.except intSeq1 emptyIntSeq
         VerifySeqsEqual emptyIntSeq <| Seq.except emptyIntSeq emptyIntSeq
         VerifySeqsEqual emptyIntSeq <| Seq.except intSeq1 intSeq1

tests/FSharp.Core.UnitTests/FSharp.Core/Microsoft.FSharp.Collections/SeqModule2.fs

@@ -479,7 +479,7 @@ type SeqModule2() =
     member _.Length() =
 
          // integer seq  
-        let resultInt = Seq.length {1..8}
+        let resultInt = Seq.length (seq {1..8})
         if resultInt <> 8 then Assert.Fail()
         
         // string Seq    
@@ -505,7 +505,7 @@ type SeqModule2() =
             | _ when x % 2 = 0 -> 10*x            
             | _ -> x
        
-        let resultInt = Seq.map funcInt { 1..10 }
+        let resultInt = Seq.map funcInt (seq { 1..10 })
         let expectedint = seq [1;20;3;40;5;60;7;80;9;100]
         
         VerifySeqsEqual expectedint resultInt
@@ -531,7 +531,7 @@ type SeqModule2() =
     member _.Map2() =
          // integer Seq
         let funcInt x y = x+y
-        let resultInt = Seq.map2 funcInt { 1..10 } {2..2..20} 
+        let resultInt = Seq.map2 funcInt (seq { 1..10 }) (seq {2..2..20})
         let expectedint = seq [3;6;9;12;15;18;21;24;27;30]
         
         VerifySeqsEqual expectedint resultInt
@@ -558,16 +558,16 @@ type SeqModule2() =
     member _.Map3() = 
         // Integer seq
         let funcInt a b c = (a + b) * c
-        let resultInt = Seq.map3 funcInt { 1..8 } { 2..9 } { 3..10 }
+        let resultInt = Seq.map3 funcInt (seq { 1..8 }) (seq { 2..9 }) (seq { 3..10 })
         let expectedInt = seq [9; 20; 35; 54; 77; 104; 135; 170]
         VerifySeqsEqual expectedInt resultInt
 
         // First seq is shorter
-        VerifySeqsEqual (seq [9; 20]) (Seq.map3 funcInt { 1..2 } { 2..9 } { 3..10 })
+        VerifySeqsEqual (seq [9; 20]) (Seq.map3 funcInt (seq { 1..2 }) (seq { 2..9 }) (seq { 3..10 }))
         // Second seq is shorter
-        VerifySeqsEqual (seq [9; 20; 35]) (Seq.map3 funcInt { 1..8 } { 2..4 } { 3..10 })
+        VerifySeqsEqual (seq [9; 20; 35]) (Seq.map3 funcInt (seq { 1..8 }) (seq { 2..4 }) (seq { 3..10 }))
         // Third seq is shorter
-        VerifySeqsEqual (seq [9; 20; 35; 54]) (Seq.map3 funcInt { 1..8 } { 2..6 } { 3..6 })
+        VerifySeqsEqual (seq [9; 20; 35; 54]) (Seq.map3 funcInt (seq { 1..8 }) (seq { 2..6 }) (seq { 3..6 }))
 
         // String seq
         let funcStr a b c = a + b + c
@@ -812,7 +812,7 @@ type SeqModule2() =
     member _.Collect() =
          // integer Seq
         let funcInt x = seq [x+1]
-        let resultInt = Seq.collect funcInt { 1..10 } 
+        let resultInt = Seq.collect funcInt (seq { 1..10 })
        
         let expectedint = seq {2..11}
         
@@ -843,7 +843,7 @@ type SeqModule2() =
 
          // integer Seq
         let funcInt x y = x+y
-        let resultInt = Seq.mapi funcInt { 10..2..20 } 
+        let resultInt = Seq.mapi funcInt (seq { 10..2..20 })
         let expectedint = seq [10;13;16;19;22;25]
         
         VerifySeqsEqual expectedint resultInt
@@ -871,7 +871,7 @@ type SeqModule2() =
     member _.Mapi2() =
          // integer Seq
         let funcInt x y z = x+y+z
-        let resultInt = Seq.mapi2 funcInt { 1..10 } {2..2..20}
+        let resultInt = Seq.mapi2 funcInt (seq { 1..10 }) (seq {2..2..20})
         let expectedint = seq [3;7;11;15;19;23;27;31;35;39]
 
         VerifySeqsEqual expectedint resultInt
@@ -907,7 +907,7 @@ type SeqModule2() =
     member _.Indexed() =
 
          // integer Seq
-        let resultInt = Seq.indexed { 10..2..20 }
+        let resultInt = Seq.indexed (seq { 10..2..20 })
         let expectedint = seq [(0,10);(1,12);(2,14);(3,16);(4,18);(5,20)]
 
         VerifySeqsEqual expectedint resultInt
@@ -931,7 +931,7 @@ type SeqModule2() =
     [<Fact>]
     member _.Max() =
          // integer Seq
-        let resultInt = Seq.max { 10..20 } 
+        let resultInt = Seq.max (seq { 10..20 })
         
         Assert.AreEqual(20,resultInt)
         
@@ -954,7 +954,7 @@ type SeqModule2() =
     
         // integer Seq
         let funcInt x = x % 8
-        let resultInt = Seq.maxBy funcInt { 2..2..20 } 
+        let resultInt = Seq.maxBy funcInt (seq { 2..2..20 })
         Assert.AreEqual(6,resultInt)
         
         // string Seq
@@ -976,7 +976,7 @@ type SeqModule2() =
     
         // integer Seq
         let funcInt x = x % 8
-        let resultInt = Seq.minBy funcInt { 2..2..20 } 
+        let resultInt = Seq.minBy funcInt (seq { 2..2..20 })
         Assert.AreEqual(8,resultInt)
         
         // string Seq
@@ -998,7 +998,7 @@ type SeqModule2() =
     member _.Min() =
 
          // integer Seq
-        let resultInt = Seq.min { 10..20 } 
+        let resultInt = Seq.min (seq { 10..20 })
         Assert.AreEqual(10,resultInt)
         
         // string Seq
@@ -1017,7 +1017,7 @@ type SeqModule2() =
     [<Fact>]
     member _.Item() =
          // integer Seq
-        let resultInt = Seq.item 3 { 10..20 }
+        let resultInt = Seq.item 3 (seq { 10..20 })
         Assert.AreEqual(13, resultInt)
 
         // string Seq
@@ -1033,11 +1033,11 @@ type SeqModule2() =
 
         // Negative index
         for i = -1 downto -10 do
-           CheckThrowsArgumentException (fun () -> Seq.item i { 10 .. 20 } |> ignore)
+           CheckThrowsArgumentException (fun () -> Seq.item i (seq { 10 .. 20 }) |> ignore)
 
         // Out of range
         for i = 11 to 20 do
-           CheckThrowsArgumentException (fun () -> Seq.item i { 10 .. 20 } |> ignore)
+           CheckThrowsArgumentException (fun () -> Seq.item i (seq { 10 .. 20 }) |> ignore)
 
     [<Fact>]
     member _.``item should fail with correct number of missing elements``() =
@@ -1057,7 +1057,7 @@ type SeqModule2() =
     member _.Of_Array() =
          // integer Seq
         let resultInt = Seq.ofArray [|1..10|]
-        let expectedInt = {1..10}
+        let expectedInt = seq {1..10}
          
         VerifySeqsEqual expectedInt resultInt
         
@@ -1076,7 +1076,7 @@ type SeqModule2() =
     member _.Of_List() =
          // integer Seq
         let resultInt = Seq.ofList [1..10]
-        let expectedInt = {1..10}
+        let expectedInt = seq {1..10}
          
         VerifySeqsEqual expectedInt resultInt
         
@@ -1095,7 +1095,7 @@ type SeqModule2() =
     [<Fact>]
     member _.Pairwise() =
          // integer Seq
-        let resultInt = Seq.pairwise {1..3}
+        let resultInt = Seq.pairwise (seq {1..3})
        
         let expectedInt = seq [1,2;2,3]
          
@@ -1182,7 +1182,7 @@ type SeqModule2() =
     member _.Scan() =
         // integer Seq
         let funcInt x y = x+y
-        let resultInt = Seq.scan funcInt 9 {1..10}
+        let resultInt = Seq.scan funcInt 9 (seq {1..10})
         let expectedInt = seq [9;10;12;15;19;24;30;37;45;54;64]
         VerifySeqsEqual expectedInt resultInt
         
@@ -1207,7 +1207,7 @@ type SeqModule2() =
     member _.ScanBack() =
         // integer Seq
         let funcInt x y = x+y
-        let resultInt = Seq.scanBack funcInt { 1..10 } 9
+        let resultInt = Seq.scanBack funcInt (seq { 1..10 }) 9
         let expectedInt = seq [64;63;61;58;54;49;43;36;28;19;9]
         VerifySeqsEqual expectedInt resultInt
 
@@ -1313,7 +1313,7 @@ type SeqModule2() =
 
         // integer Seq
         let resultInt = Seq.sort (seq [1;3;2;4;6;5;7])
-        let expectedInt = {1..7}
+        let expectedInt = seq {1..7}
         VerifySeqsEqual expectedInt resultInt
         
         // string Seq
@@ -1960,7 +1960,7 @@ type SeqModule2() =
     [<Fact>]
     member _.tryItem() =
         // integer Seq
-        let resultInt = Seq.tryItem 3 { 10..20 }
+        let resultInt = Seq.tryItem 3 (seq { 10..20 })
         Assert.AreEqual(Some(13), resultInt)
 
         // string Seq
@@ -1976,11 +1976,11 @@ type SeqModule2() =
         CheckThrowsArgumentNullException (fun () -> Seq.tryItem 3 nullSeq |> ignore)
 
         // Negative index
-        let resultNegativeIndex = Seq.tryItem -1 { 10..20 }
+        let resultNegativeIndex = Seq.tryItem -1 (seq { 10..20 })
         Assert.AreEqual(None, resultNegativeIndex)
 
         // Index greater than length
-        let resultIndexGreater = Seq.tryItem 31 { 10..20 }
+        let resultIndexGreater = Seq.tryItem 31 (seq { 10..20 })
         Assert.AreEqual(None, resultIndexGreater)
         
     [<Fact>]

tests/FSharp.Core.UnitTests/FSharp.Core/PrimTypes.fs

@@ -821,7 +821,7 @@ module internal RangeTestsHelpers =
         enumerator.Current |> ignore
 
     let inline exceptions zero one two =
-        Assert.Throws (typeof<System.ArgumentException>, (fun () -> {one .. zero .. two} |> Seq.length |> ignore)) |> ignore
+        Assert.Throws (typeof<System.ArgumentException>, (fun () -> seq {one .. zero .. two} |> Seq.length |> ignore)) |> ignore
         Assert.Throws (typeof<System.ArgumentException>, (fun () -> [one .. zero .. two] |> List.length |> ignore)) |> ignore
         Assert.Throws (typeof<System.ArgumentException>, (fun () -> [|one .. zero .. two|] |> Array.length |> ignore)) |> ignore
 
@@ -831,10 +831,10 @@ module internal RangeTestsHelpers =
         Assert.Throws (typeof<System.InvalidOperationException>, (fun () -> regressionExceptionAfterEndVariableStepIntegralRange zero two))    |> ignore
 
     let inline common (min0, min1, min2, min3) (max0, max1, max2, max3) (zero, one, two, three) =
-        Assert.AreEqual (seq {yield min0; yield min1; yield min2; yield min3}, {min0 ..          min3})
+        Assert.AreEqual (seq {yield min0; yield min1; yield min2; yield min3}, seq {min0 ..          min3})
-        Assert.AreEqual (seq {min0; min1; min2; min3}, {min0 .. one   .. min3})
+        Assert.AreEqual (seq {min0; min1; min2; min3}, seq {min0 .. one   .. min3})
-        Assert.AreEqual (seq {min0; min2}, {min0 .. two   .. min3})
+        Assert.AreEqual (seq {min0; min2}, seq {min0 .. two   .. min3})
-        Assert.AreEqual (seq {min0; min3}, {min0 .. three .. min3})
+        Assert.AreEqual (seq {min0; min3}, seq {min0 .. three .. min3})
 
         Assert.AreEqual ([min0; min1; min2; min3], [min0 ..          min3])
         Assert.AreEqual ([min0; min1; min2; min3], [min0 .. one   .. min3])
@@ -846,10 +846,10 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([|min0; min2|], [|min0 .. two   .. min3|])
         Assert.AreEqual ([|min0; min3|], [|min0 .. three .. min3|])
 
-        Assert.AreEqual (seq {yield max3; yield max2; yield max1; yield max0}, {max3 ..          max0})
+        Assert.AreEqual (seq {yield max3; yield max2; yield max1; yield max0}, seq {max3 ..          max0})
-        Assert.AreEqual (seq {max3; max2; max1; max0}, {max3 .. one   .. max0})
+        Assert.AreEqual (seq {max3; max2; max1; max0}, seq {max3 .. one   .. max0})
-        Assert.AreEqual (seq {max3; max1}, {max3 .. two   .. max0})
+        Assert.AreEqual (seq {max3; max1}, seq {max3 .. two   .. max0})
-        Assert.AreEqual (seq {max3; max0}, {max3 .. three .. max0})
+        Assert.AreEqual (seq {max3; max0}, seq {max3 .. three .. max0})
 
         Assert.AreEqual ([max3; max2; max1; max0], [max3 ..          max0])
         Assert.AreEqual ([max3; max2; max1; max0], [max3 .. one   .. max0])
@@ -861,10 +861,10 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([|max3; max1|], [|max3 .. two   .. max0|])
         Assert.AreEqual ([|max3; max0|], [|max3 .. three .. max0|])
 
-        Assert.AreEqual (Seq.empty, {max0 ..          min0})
+        Assert.AreEqual (Seq.empty, seq {max0 ..          min0})
-        Assert.AreEqual (Seq.empty, {max0 .. one   .. min0})
+        Assert.AreEqual (Seq.empty, seq {max0 .. one   .. min0})
-        Assert.AreEqual (Seq.empty, {max0 .. two   .. min0})
+        Assert.AreEqual (Seq.empty, seq {max0 .. two   .. min0})
-        Assert.AreEqual (Seq.empty, {max0 .. three .. min0})
+        Assert.AreEqual (Seq.empty, seq {max0 .. three .. min0})
 
         Assert.AreEqual ([], [max0 ..          min0])
         Assert.AreEqual ([], [max0 .. one   .. min0])
@@ -880,8 +880,8 @@ module internal RangeTestsHelpers =
 
         // tests for singleStepRangeEnumerator, as it only is used if start and/or end are not the
         // minimum or maximum of the number range and it is counting by 1s
-        Assert.AreEqual (seq {min1; min2; min3}, {min1 .. min3})
+        Assert.AreEqual (seq {min1; min2; min3}, seq {min1 .. min3})
-        Assert.AreEqual (seq {max3; max2; max1}, {max3 .. max1})
+        Assert.AreEqual (seq {max3; max2; max1}, seq {max3 .. max1})
 
         Assert.AreEqual ([min1; min2; min3], [min1 .. min3])
         Assert.AreEqual ([max3; max2; max1], [max3 .. max1])
@@ -903,10 +903,10 @@ module internal RangeTestsHelpers =
 
         common (min0, min1, min2, min3) (max0, max1, max2, max3) (zero, one, two, three)
 
-        Assert.AreEqual (seq { min0; min0 + max0; min0 + max0 + max0 }, {min0 .. max0 .. max0})
+        Assert.AreEqual (seq { min0; min0 + max0; min0 + max0 + max0 }, seq {min0 .. max0 .. max0})
-        Assert.AreEqual (seq { min0; min0 + max1; min0 + max1 + max1 }, {min0 .. max1 .. max0})
+        Assert.AreEqual (seq { min0; min0 + max1; min0 + max1 + max1 }, seq {min0 .. max1 .. max0})
-        Assert.AreEqual (seq { min0; min0 + max2; min0 + max2 + max2 }, {min0 .. max2 .. max0})
+        Assert.AreEqual (seq { min0; min0 + max2; min0 + max2 + max2 }, seq {min0 .. max2 .. max0})
-        Assert.AreEqual (seq { min0; min0 + max3; min0 + max3 + max3 }, {min0 .. max3 .. max0})
+        Assert.AreEqual (seq { min0; min0 + max3; min0 + max3 + max3 }, seq {min0 .. max3 .. max0})
 
         Assert.AreEqual ([ min0; min0 + max0; min0 + max0 + max0 ], [min0 .. max0 .. max0])
         Assert.AreEqual ([ min0; min0 + max1; min0 + max1 + max1 ], [min0 .. max1 .. max0])
@@ -918,9 +918,9 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([| min0; min0 + max2; min0 + max2 + max2 |], [|min0 .. max2 .. max0|])
         Assert.AreEqual ([| min0; min0 + max3; min0 + max3 + max3 |], [|min0 .. max3 .. max0|])
 
-        Assert.AreEqual (seq {min3; min2; min1; min0}, {min3 .. -one   .. min0})
+        Assert.AreEqual (seq {min3; min2; min1; min0}, seq {min3 .. -one   .. min0})
-        Assert.AreEqual (seq {min3; min1}, {min3 .. -two   .. min0})
+        Assert.AreEqual (seq {min3; min1}, seq {min3 .. -two   .. min0})
-        Assert.AreEqual (seq {min3; min0}, {min3 .. -three .. min0})
+        Assert.AreEqual (seq {min3; min0}, seq {min3 .. -three .. min0})
 
         Assert.AreEqual ([min3; min2; min1; min0], [min3 .. -one   .. min0])
         Assert.AreEqual ([min3; min1], [min3 .. -two   .. min0])
@@ -930,9 +930,9 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([|min3; min1|], [|min3 .. -two   .. min0|])
         Assert.AreEqual ([|min3; min0|], [|min3 .. -three .. min0|])
 
-        Assert.AreEqual (seq {max0; max1; max2; max3}, {max0 .. -one   .. max3})
+        Assert.AreEqual (seq {max0; max1; max2; max3}, seq {max0 .. -one   .. max3})
-        Assert.AreEqual (seq {max0; max2}, {max0 .. -two   .. max3})
+        Assert.AreEqual (seq {max0; max2}, seq {max0 .. -two   .. max3})
-        Assert.AreEqual (seq {max0; max3}, {max0 .. -three .. max3})
+        Assert.AreEqual (seq {max0; max3}, seq {max0 .. -three .. max3})
 
         Assert.AreEqual ([max0; max1; max2; max3], [max0 .. -one   .. max3])
         Assert.AreEqual ([max0; max2], [max0 .. -two   .. max3])
@@ -942,9 +942,9 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([|max0; max2|], [|max0 .. -two   .. max3|])
         Assert.AreEqual ([|max0; max3|], [|max0 .. -three .. max3|])
 
-        Assert.AreEqual (Seq.empty, {min0 .. -one   .. max0})
+        Assert.AreEqual (Seq.empty, seq {min0 .. -one   .. max0})
-        Assert.AreEqual (Seq.empty, {min0 .. -two   .. max0})
+        Assert.AreEqual (Seq.empty, seq {min0 .. -two   .. max0})
-        Assert.AreEqual (Seq.empty, {min0 .. -three .. max0})
+        Assert.AreEqual (Seq.empty, seq {min0 .. -three .. max0})
 
         Assert.AreEqual ([], [min0 .. -one   .. max0])
         Assert.AreEqual ([], [min0 .. -two   .. max0])
@@ -954,10 +954,10 @@ module internal RangeTestsHelpers =
         Assert.AreEqual ([||], [|min0 .. -two   .. max0|])
         Assert.AreEqual ([||], [|min0 .. -three .. max0|])
 
-        Assert.AreEqual (seq {max0; max0 + min0}, {max0 .. min0 .. min0})
+        Assert.AreEqual (seq {max0; max0 + min0}, seq {max0 .. min0 .. min0})
-        Assert.AreEqual (seq {max0; max0 + min1; max0 + min1 + min1 }, {max0 .. min1 .. min0})
+        Assert.AreEqual (seq {max0; max0 + min1; max0 + min1 + min1 }, seq {max0 .. min1 .. min0})
-        Assert.AreEqual (seq {max0; max0 + min2; max0 + min2 + min2 }, {max0 .. min2 .. min0})
+        Assert.AreEqual (seq {max0; max0 + min2; max0 + min2 + min2 }, seq {max0 .. min2 .. min0})
-        Assert.AreEqual (seq {max0; max0 + min3; max0 + min3 + min3 }, {max0 .. min3 .. min0})
+        Assert.AreEqual (seq {max0; max0 + min3; max0 + min3 + min3 }, seq {max0 .. min3 .. min0})
 
         Assert.AreEqual ([max0; max0 + min0], [max0 .. min0 .. min0])
         Assert.AreEqual ([max0; max0 + min1; max0 + min1 + min1 ], [max0 .. min1 .. min0])
@@ -983,10 +983,10 @@ module internal RangeTestsHelpers =
 
         common (min0, min1, min2, min3) (max0, max1, max2, max3) (zero, one, two, three)
 
-        Assert.AreEqual (seq {yield min0; yield min0 + max0}, {min0 .. max0 .. max0})
+        Assert.AreEqual (seq {yield min0; yield min0 + max0}, seq {min0 .. max0 .. max0})
-        Assert.AreEqual (seq {min0; min0 + max1}, {min0 .. max1 .. max0})
+        Assert.AreEqual (seq {min0; min0 + max1}, seq {min0 .. max1 .. max0})
-        Assert.AreEqual (seq {min0; min0 + max2}, {min0 .. max2 .. max0})
+        Assert.AreEqual (seq {min0; min0 + max2}, seq {min0 .. max2 .. max0})
-        Assert.AreEqual (seq {min0; min0 + max3}, {min0 .. max3 .. max0})
+        Assert.AreEqual (seq {min0; min0 + max3}, seq {min0 .. max3 .. max0})
 
         Assert.AreEqual ([min0; min0 + max0], [min0 .. max0 .. max0])
         Assert.AreEqual ([min0; min0 + max1], [min0 .. max1 .. max0])
@@ -1064,15 +1064,15 @@ module RangeTests =
             Assert.AreEqual(256, let mutable c = 0 in for _ in System.SByte.MinValue..1y..System.SByte.MaxValue do c <- c + 1 done; c)
             Assert.AreEqual(256, let mutable c = 0 in for _ in System.SByte.MaxValue .. -1y .. System.SByte.MinValue do c <- c + 1 done; c)
 
-            Assert.AreEqual(allSBytesSeq, {System.SByte.MinValue..System.SByte.MaxValue})
+            Assert.AreEqual(allSBytesSeq, seq {System.SByte.MinValue..System.SByte.MaxValue})
             Assert.AreEqual(allSBytesList, [System.SByte.MinValue..System.SByte.MaxValue])
             Assert.AreEqual(allSBytesArray, [|System.SByte.MinValue..System.SByte.MaxValue|])
 
-            Assert.AreEqual(allSBytesSeq, {System.SByte.MinValue..1y..System.SByte.MaxValue})
+            Assert.AreEqual(allSBytesSeq, seq {System.SByte.MinValue..1y..System.SByte.MaxValue})
             Assert.AreEqual(allSBytesList, [System.SByte.MinValue..1y..System.SByte.MaxValue])
             Assert.AreEqual(allSBytesArray, [|System.SByte.MinValue..1y..System.SByte.MaxValue|])
 
-            Assert.AreEqual(Seq.rev allSBytesSeq, {System.SByte.MaxValue .. -1y .. System.SByte.MinValue})
+            Assert.AreEqual(Seq.rev allSBytesSeq, seq {System.SByte.MaxValue .. -1y .. System.SByte.MinValue})
             Assert.AreEqual(List.rev allSBytesList, [System.SByte.MaxValue .. -1y .. System.SByte.MinValue])
             Assert.AreEqual(Array.rev allSBytesArray, [|System.SByte.MaxValue .. -1y .. System.SByte.MinValue|])
 
@@ -1083,11 +1083,11 @@ module RangeTests =
             Assert.AreEqual(256, let mutable c = 0 in for _ in System.Byte.MinValue..System.Byte.MaxValue do c <- c + 1 done; c)
             Assert.AreEqual(256, let mutable c = 0 in for _ in System.Byte.MinValue..1uy..System.Byte.MaxValue do c <- c + 1 done; c)
 
-            Assert.AreEqual(allBytesSeq, {System.Byte.MinValue..System.Byte.MaxValue})
+            Assert.AreEqual(allBytesSeq, seq {System.Byte.MinValue..System.Byte.MaxValue})
             Assert.AreEqual(allBytesList, [System.Byte.MinValue..System.Byte.MaxValue])
             Assert.AreEqual(allBytesArray, [|System.Byte.MinValue..System.Byte.MaxValue|])
 
-            Assert.AreEqual(allBytesSeq, {System.Byte.MinValue..1uy..System.Byte.MaxValue})
+            Assert.AreEqual(allBytesSeq, seq {System.Byte.MinValue..1uy..System.Byte.MaxValue})
             Assert.AreEqual(allBytesList, [System.Byte.MinValue..1uy..System.Byte.MaxValue])
             Assert.AreEqual(allBytesArray, [|System.Byte.MinValue..1uy..System.Byte.MaxValue|])
 
@@ -1141,15 +1141,15 @@ module RangeTests =
             Assert.AreEqual(256, let mutable c = 0 in for _ in min0..one..max0 do c <- c + 1 done; c)
             Assert.AreEqual(256, let mutable c = 0 in for _ in max0 .. -one .. min0 do c <- c + 1 done; c)
 
-            Assert.AreEqual(allSBytesSeq, {min0..max0})
+            Assert.AreEqual(allSBytesSeq, seq {min0..max0})
             Assert.AreEqual(allSBytesList, [min0..max0])
             Assert.AreEqual(allSBytesArray, [|min0..max0|])
 
-            Assert.AreEqual(allSBytesSeq, {min0..one..max0})
+            Assert.AreEqual(allSBytesSeq, seq {min0..one..max0})
             Assert.AreEqual(allSBytesList, [min0..one..max0])
             Assert.AreEqual(allSBytesArray, [|min0..one..max0|])
 
-            Assert.AreEqual(Seq.rev allSBytesSeq, {max0 .. -one .. min0})
+            Assert.AreEqual(Seq.rev allSBytesSeq, seq {max0 .. -one .. min0})
             Assert.AreEqual(List.rev allSBytesList, [max0 .. -one .. min0])
             Assert.AreEqual(Array.rev allSBytesArray, [|max0 .. -one .. min0|])
 
@@ -1160,11 +1160,11 @@ module RangeTests =
             Assert.AreEqual(256, let mutable c = 0 in for _ in min0..max0 do c <- c + 1 done; c)
             Assert.AreEqual(256, let mutable c = 0 in for _ in min0..one..max0 do c <- c + 1 done; c)
 
-            Assert.AreEqual(allBytesSeq, {min0..max0})
+            Assert.AreEqual(allBytesSeq, seq {min0..max0})
             Assert.AreEqual(allBytesList, [min0..max0])
             Assert.AreEqual(allBytesArray, [|min0..max0|])
 
-            Assert.AreEqual(allBytesSeq, {min0..one..max0})
+            Assert.AreEqual(allBytesSeq, seq {min0..one..max0})
             Assert.AreEqual(allBytesList, [min0..one..max0])
             Assert.AreEqual(allBytesArray, [|min0..one..max0|])
 

tests/FSharp.Core.UnitTests/TestFrameworkHelpers.fs

@@ -72,7 +72,7 @@ module private Impl =
                     let ub = a1.GetUpperBound(0)
                     if lb <> a2.GetLowerBound(0) || ub <> a2.GetUpperBound(0) then false
                     else
-                        {lb..ub} |> Seq.forall(fun i -> equals (a1.GetValue(i)) (a2.GetValue(i)))    
+                        seq {lb..ub} |> Seq.forall(fun i -> equals (a1.GetValue(i)) (a2.GetValue(i)))    
         |   _ ->
                 Object.Equals(expected, actual)
 

vsintegration/src/FSharp.Editor/CodeFixes/AddMissingSeq.fs

@@ -0,0 +1,77 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Microsoft.VisualStudio.FSharp.Editor
+
+open System.Collections.Immutable
+open System.Composition
+open FSharp.Compiler.Syntax
+open FSharp.Compiler.Text
+open Microsoft.CodeAnalysis.CodeFixes
+open Microsoft.CodeAnalysis.Text
+open CancellableTasks
+
+[<Sealed>]
+[<ExportCodeFixProvider(FSharpConstants.FSharpLanguageName, Name = CodeFix.ChangeToUpcast); Shared>]
+type internal AddMissingSeqCodeFixProvider() =
+    inherit CodeFixProvider()
+
+    static let title = SR.AddMissingSeq()
+    static let fixableDiagnosticIds = ImmutableArray.Create("FS3873", "FS0740")
+
+    override _.FixableDiagnosticIds = fixableDiagnosticIds
+    override this.RegisterCodeFixesAsync context = context.RegisterFsharpFix this
+    override this.GetFixAllProvider() = this.RegisterFsharpFixAll()
+
+    interface IFSharpCodeFixProvider with
+        member _.GetCodeFixIfAppliesAsync context =
+            cancellableTask {
+                let! sourceText = context.GetSourceTextAsync()
+                let! parseFileResults = context.Document.GetFSharpParseResultsAsync(nameof AddMissingSeqCodeFixProvider)
+
+                let getSourceLineStr line =
+                    sourceText.Lines[Line.toZ line].ToString()
+
+                let range =
+                    RoslynHelpers.TextSpanToFSharpRange(context.Document.FilePath, context.Span, sourceText)
+
+                let needsParens =
+                    (range.Start, parseFileResults.ParseTree)
+                    ||> ParsedInput.exists (fun path node ->
+                        match path, node with
+                        | SyntaxNode.SynExpr outer :: _, SyntaxNode.SynExpr(expr & SynExpr.ComputationExpr _) when
+                            expr.Range |> Range.equals range
+                            ->
+                            let seqRange =
+                                range
+                                |> Range.withEnd (Position.mkPos range.Start.Line (range.Start.Column + 3))
+
+                            let inner =
+                                SynExpr.App(
+                                    ExprAtomicFlag.NonAtomic,
+                                    false,
+                                    SynExpr.Ident(Ident(nameof seq, seqRange)),
+                                    expr,
+                                    Range.unionRanges seqRange expr.Range
+                                )
+
+                            let outer =
+                                match outer with
+                                | SynExpr.App(flag, isInfix, funcExpr, _, outerAppRange) ->
+                                    SynExpr.App(flag, isInfix, funcExpr, inner, outerAppRange)
+                                | outer -> outer
+
+                            inner
+                            |> SynExpr.shouldBeParenthesizedInContext getSourceLineStr (SyntaxNode.SynExpr outer :: path)
+                        | _ -> false)
+
+                let text = sourceText.ToString(TextSpan(context.Span.Start, context.Span.Length))
+                let newText = if needsParens then $"(seq {text})" else $"seq {text}"
+
+                return
+                    ValueSome
+                        {
+                            Name = CodeFix.AddMissingSeq
+                            Message = title
+                            Changes = [ TextChange(context.Span, newText) ]
+                        }
+            }

vsintegration/src/FSharp.Editor/Common/Constants.fs

@@ -208,3 +208,6 @@ module internal CodeFix =
 
     [<Literal>]
     let RemoveUnnecessaryParentheses = "RemoveUnnecessaryParentheses"
+
+    [<Literal>]
+    let AddMissingSeq = "AddMissingSeq"

vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj

@@ -141,6 +141,7 @@
     <Compile Include="CodeFixes\RenameParamToMatchSignature.fs" />
     <Compile Include="CodeFixes\UseTripleQuotedInterpolation.fs" />
     <Compile Include="CodeFixes\RemoveUnnecessaryParentheses.fs" />
+    <Compile Include="CodeFixes\AddMissingSeq.fs" />
     <Compile Include="Build\SetGlobalPropertiesForSdkProjects.fs" />
     <Compile Include="AutomaticCompletion\BraceCompletionSessionProvider.fsi" />
     <Compile Include="AutomaticCompletion\BraceCompletionSessionProvider.fs" />

vsintegration/src/FSharp.Editor/FSharp.Editor.resx

@@ -359,6 +359,9 @@ Use live (unsaved) buffers for analysis</value>
   <data name="RemoveUnnecessaryParentheses" xml:space="preserve">
     <value>Remove unnecessary parentheses</value>
   </data>
+  <data name="AddMissingSeq" xml:space="preserve">
+    <value>Add missing 'seq'</value>
+  </data>
   <data name="RemarksHeader" xml:space="preserve">
     <value>Remarks:</value>
   </data>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.cs.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Přidat chybějící parametr člena instance</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Přidejte klíčové slovo new.</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.de.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Fehlenden Instanzmemberparameter hinzufügen</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Schlüsselwort "new" hinzufügen</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.es.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Agregar parámetro de miembro de instancia que falta</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Agregar "nueva" palabra clave</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.fr.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Ajouter un paramètre de membre d’instance manquant</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Ajouter le mot clé 'new'</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.it.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Aggiungi parametro membro di istanza mancante</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Aggiungi la parola chiave 'new'</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.ja.xlf

@@ -17,6 +17,11 @@
         <target state="translated">見つからないインスタンス メンバー パラメーターを追加する</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">'new' キーワードを追加する</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.ko.xlf

@@ -17,6 +17,11 @@
         <target state="translated">누락된 인스턴스 멤버 매개 변수 추가</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">'new' 키워드 추가</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.pl.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Dodaj brakujący parametr składowej wystąpienia</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Dodaj słowo kluczowe „new”</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.pt-BR.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Adicionar parâmetro de membro de instância ausente</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Adicionar a palavra-chave 'new'</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.ru.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Добавить отсутствующий параметр экземплярного элемента</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">Добавить ключевое слово "new"</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.tr.xlf

@@ -17,6 +17,11 @@
         <target state="translated">Eksik örnek üye parametresini ekleyin</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">'new' anahtar sözcüğünü ekleme</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.zh-Hans.xlf

@@ -17,6 +17,11 @@
         <target state="translated">添加缺少的实例成员参数</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">添加“新”关键字</target>

vsintegration/src/FSharp.Editor/xlf/FSharp.Editor.zh-Hant.xlf

@@ -17,6 +17,11 @@
         <target state="translated">新增缺少的執行個體成員參數</target>
         <note />
       </trans-unit>
+      <trans-unit id="AddMissingSeq">
+        <source>Add missing 'seq'</source>
+        <target state="new">Add missing 'seq'</target>
+        <note />
+      </trans-unit>
       <trans-unit id="AddNewKeyword">
         <source>Add 'new' keyword</source>
         <target state="translated">新增 'new' 關鍵字</target>

vsintegration/tests/FSharp.Editor.Tests/CodeFixes/AddMissingSeqTests.fs

@@ -0,0 +1,239 @@
+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+module FSharp.Editor.Tests.CodeFixes.AddMissingSeqTests
+
+open Microsoft.VisualStudio.FSharp.Editor
+open Xunit
+open CodeFixTestFramework
+
+let private codeFix = AddMissingSeqCodeFixProvider()
+
+// This can be changed to Auto when featureDeprecatePlacesWhereSeqCanBeOmitted is out of preview.
+let mode = WithOption "--langversion:preview"
+
+[<Fact>]
+let ``FS3873 — Adds missing seq before { start..finish }`` () =
+    let code = "let xs = { 1..10 }"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = seq { 1..10 }"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds missing seq before { start..step..finish }`` () =
+    let code = "let xs = { 1..5..10 }"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = seq { 1..5..10 }"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS0740 — Adds missing seq before { x; y }`` () =
+    let code = "let xs = { 1; 10 }"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = seq { 1; 10 }"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds missing seq before yield { start..finish }`` () =
+    let code = "let xs = [| yield { 1..100 } |]"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = [| yield seq { 1..100 } |]"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds missing seq before yield { start..finish } multiline`` () =
+    let code =
+        """
+let xs = [| yield seq { 1..100 }
+            yield { 1..100 } |]
+"""
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode =
+                    """
+let xs = [| yield seq { 1..100 }
+            yield seq { 1..100 } |]
+"""
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds parens when needed — app`` () =
+    let code = "let xs = id { 1..10 }"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = id (seq { 1..10 })"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds parens when needed — app parens`` () =
+    let code = "let xs = ResizeArray({ 1..10 })"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = ResizeArray(seq { 1..10 })"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds parens when needed — foreach`` () =
+    let code = "[ for x in { 1..10 } -> x ]"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "[ for x in seq { 1..10 } -> x ]"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds parens when needed — dot`` () =
+    let code = "let s = { 1..10 }.ToString ()"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let s = (seq { 1..10 }).ToString ()"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS0740 — Adds parens when needed — app`` () =
+    let code = "let xs = id { 1; 10 }"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let xs = id (seq { 1; 10 })"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS0740 — Adds parens when needed — dot`` () =
+    let code = "let s = { 1; 10 }.ToString ()"
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode = "let s = (seq { 1; 10 }).ToString ()"
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS3873 — Adds parens when needed — multiline`` () =
+    let code =
+        """
+let xs =
+    id {
+        1..10
+    }
+"""
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode =
+                    """
+let xs =
+    id (seq {
+        1..10
+    })
+"""
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)
+
+[<Fact>]
+let ``FS0740 — Adds parens when needed — multiline`` () =
+    let code =
+        """
+let xs =
+    id {
+        1; 10
+    }
+"""
+
+    let expected =
+        Some
+            {
+                Message = "Add missing 'seq'"
+                FixedCode =
+                    """
+let xs =
+    id (seq {
+        1; 10
+    })
+"""
+            }
+
+    let actual = codeFix |> tryFix code mode
+
+    Assert.Equal(expected, actual)

vsintegration/tests/FSharp.Editor.Tests/FSharp.Editor.Tests.fsproj

@@ -72,6 +72,7 @@
     <Compile Include="CodeFixes\ConvertCSharpUsingToFSharpOpenTests.fs" />
     <Compile Include="CodeFixes\ReplaceWithSuggestionTests.fs" />
     <Compile Include="CodeFixes\RemoveUnnecessaryParenthesesTests.fs" />
+    <Compile Include="CodeFixes\AddMissingSeqTests.fs" />
     <Compile Include="Refactors\RefactorTestFramework.fs" />
     <Compile Include="Refactors\AddReturnTypeTests.fs" />
     <Compile Include="Hints\HintTestFramework.fs" />