Try-with inside seq{} expressions

src/Compiler/Checking/CheckComputationExpressions.fs

@@ -1854,6 +1854,13 @@ let mkSeqFinally (cenv: cenv) env m genTy e1 e2 =
     let e1 = mkCoerceIfNeeded cenv.g (mkSeqTy cenv.g genResultTy) (tyOfExpr cenv.g e1) e1
     mkCallSeqFinally cenv.g m genResultTy e1 e2 
 
+let mkSeqTryWith (cenv: cenv) env m genTy origSeq exnFilter exnHandler =
+    let g = cenv.g
+    let genResultTy = NewInferenceType g
+    UnifyTypes cenv env m genTy (mkSeqTy cenv.g genResultTy)
+    let origSeq = mkCoerceIfNeeded cenv.g (mkSeqTy cenv.g genResultTy) (tyOfExpr cenv.g origSeq) origSeq
+    mkCallSeqTryWith cenv.g m genResultTy origSeq exnFilter exnHandler 
+
 let mkSeqExprMatchClauses (pat, vspecs) innerExpr = 
     [MatchClause(pat, None, TTarget(vspecs, innerExpr, None), pat.Range) ] 
 
@@ -2079,8 +2086,38 @@ let TcSequenceExpression (cenv: cenv) env tpenv comp (overallTy: OverallTy) m =
 
             Some(mkLet spMatch inputExprMark matchv inputExpr matchExpr, tpenv)
 
-        | SynExpr.TryWith (trivia={ TryToWithRange = mTryToWith }) ->
-            error(Error(FSComp.SR.tcTryIllegalInSequenceExpression(), mTryToWith))
+        | SynExpr.TryWith (innerTry,withList,mTryToWith,_spTry,_spWith,trivia) ->
+            if not(g.langVersion.SupportsFeature(LanguageFeature.TryWithInSeqExpression)) then
+                 error(Error(FSComp.SR.tcTryIllegalInSequenceExpression(), mTryToWith))
+
+            let env = { env with eIsControlFlow = true }
+            let tryExpr, tpenv = 
+                let inner,tpenv = tcSequenceExprBody env genOuterTy tpenv innerTry
+                mkSeqDelayedExpr mTryToWith inner, tpenv
+
+            // Compile the pattern twice, once as a filter with all succeeding targets returning "1", and once as a proper catch block.
+            let clauses, tpenv = 
+                (tpenv, withList) ||> List.mapFold (fun tpenv (SynMatchClause(pat, cond, innerComp, m, sp, _)) ->
+                    let patR, condR, vspecs, envinner, tpenv = TcMatchPattern cenv g.exn_ty env tpenv pat cond
+                    let envinner =
+                        match sp with
+                        | DebugPointAtTarget.Yes -> { envinner with eIsControlFlow = true }
+                        | DebugPointAtTarget.No -> envinner
+                    let matchBody, tpenv = tcSequenceExprBody envinner genOuterTy tpenv innerComp
+                    let handlerClause = MatchClause(patR, condR, TTarget(vspecs, matchBody, None), patR.Range)
+                    let filterClause = MatchClause(patR, condR, TTarget([], Expr.Const(Const.Int32 1,m,g.int_ty), None), patR.Range)
+                    (handlerClause,filterClause), tpenv)
+
+            let handlers, filterClauses = List.unzip clauses
+            let withRange = trivia.WithToEndRange
+            let v1, filterExpr = CompilePatternForMatchClauses cenv env withRange withRange true FailFilter None g.exn_ty g.int_ty filterClauses
+            let v2, handlerExpr = CompilePatternForMatchClauses cenv env withRange withRange true FailFilter None g.exn_ty genOuterTy handlers
+
+            let filterLambda = mkLambda filterExpr.Range v1 (filterExpr, genOuterTy)
+            let handlerLambda = mkLambda handlerExpr.Range v2 (handlerExpr, genOuterTy)
+
+            let combinatorExpr = mkSeqTryWith cenv env mTryToWith genOuterTy tryExpr filterLambda handlerLambda
+            Some (combinatorExpr,tpenv)
 
         | SynExpr.YieldOrReturnFrom ((isYield, _), synYieldExpr, m) -> 
             let env = { env with eIsControlFlow = false }

src/Compiler/FSComp.txt

@@ -1561,6 +1561,7 @@ featureErrorForNonVirtualMembersOverrides,"Raises errors for non-virtual members
 featureWarningWhenInliningMethodImplNoInlineMarkedFunction,"Raises warnings when 'let inline ... =' is used together with [<MethodImpl(MethodImplOptions.NoInlining)>] attribute. Function is not getting inlined."
 featureArithmeticInLiterals,"Allow arithmetic and logical operations in literals"
 featureErrorReportingOnStaticClasses,"Error reporting on static classes"
+featureTryWithInSeqExpressions,"Support for try-with in sequence expressions"
 featureWarningWhenCopyAndUpdateRecordChangesAllFields,"Raises warnings when an copy-and-update record expression changes all fields of a record."
 3353,fsiInvalidDirective,"Invalid directive '#%s %s'"
 3354,tcNotAFunctionButIndexerNamedIndexingNotYetEnabled,"This value supports indexing, e.g. '%s.[index]'. The syntax '%s[index]' requires /langversion:preview. See https://aka.ms/fsharp-index-notation."

src/Compiler/Facilities/LanguageFeatures.fs

@@ -61,6 +61,7 @@ type LanguageFeature =
     | EscapeDotnetFormattableStrings
     | ArithmeticInLiterals
     | ErrorReportingOnStaticClasses
+    | TryWithInSeqExpression
     | WarningWhenCopyAndUpdateRecordChangesAllFields
 
 /// LanguageVersion management
@@ -139,6 +140,7 @@ type LanguageVersion(versionText) =
                 LanguageFeature.EscapeDotnetFormattableStrings, previewVersion
                 LanguageFeature.ArithmeticInLiterals, previewVersion
                 LanguageFeature.ErrorReportingOnStaticClasses, previewVersion
+                LanguageFeature.TryWithInSeqExpression, previewVersion
                 LanguageFeature.WarningWhenCopyAndUpdateRecordChangesAllFields, previewVersion
 
             ]
@@ -254,6 +256,7 @@ type LanguageVersion(versionText) =
         | LanguageFeature.EscapeDotnetFormattableStrings -> FSComp.SR.featureEscapeBracesInFormattableString ()
         | LanguageFeature.ArithmeticInLiterals -> FSComp.SR.featureArithmeticInLiterals ()
         | LanguageFeature.ErrorReportingOnStaticClasses -> FSComp.SR.featureErrorReportingOnStaticClasses ()
+        | LanguageFeature.TryWithInSeqExpression -> FSComp.SR.featureTryWithInSeqExpressions ()
         | LanguageFeature.WarningWhenCopyAndUpdateRecordChangesAllFields -> FSComp.SR.featureWarningWhenCopyAndUpdateRecordChangesAllFields ()
 
     /// Get a version string associated with the given feature.

src/Compiler/Facilities/LanguageFeatures.fsi

@@ -51,6 +51,7 @@ type LanguageFeature =
     | EscapeDotnetFormattableStrings
     | ArithmeticInLiterals
     | ErrorReportingOnStaticClasses
+    | TryWithInSeqExpression
     | WarningWhenCopyAndUpdateRecordChangesAllFields
 
 /// LanguageVersion management

src/Compiler/TypedTree/TcGlobals.fs

@@ -764,6 +764,7 @@ type TcGlobals(
   let v_seq_using_info             = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "EnumerateUsing"                       , None                 , None          , [vara;varb;varc], ([[varaTy];[(varaTy --> varbTy)]], mkSeqTy varcTy))
   let v_seq_generated_info         = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "EnumerateWhile"                       , None                 , None          , [varb],     ([[v_unit_ty --> v_bool_ty]; [mkSeqTy varbTy]], mkSeqTy varbTy))
   let v_seq_finally_info           = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "EnumerateThenFinally"                 , None                 , None          , [varb],     ([[mkSeqTy varbTy]; [v_unit_ty --> v_unit_ty]], mkSeqTy varbTy))
+  let v_seq_trywith_info           = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "EnumerateTryWith"                     , None                 , None          , [varb],     ([[mkSeqTy varbTy]; [mkNonGenericTy v_exn_tcr --> v_int32_ty]; [mkNonGenericTy v_exn_tcr --> mkSeqTy varbTy]], mkSeqTy varbTy))
   let v_seq_of_functions_info      = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "EnumerateFromFunctions"               , None                 , None          , [vara;varb], ([[v_unit_ty --> varaTy]; [varaTy --> v_bool_ty]; [varaTy --> varbTy]], mkSeqTy varbTy))
   let v_create_event_info          = makeIntrinsicValRef(fslib_MFRuntimeHelpers_nleref,                        "CreateEvent"                          , None                 , None          , [vara;varb], ([[varaTy --> v_unit_ty]; [varaTy --> v_unit_ty]; [(v_obj_ty --> (varbTy --> v_unit_ty)) --> varaTy]], mkIEvent2Ty varaTy varbTy))
   let v_cgh__useResumableCode_info = makeIntrinsicValRef(fslib_MFStateMachineHelpers_nleref,                   "__useResumableCode"                   , None                 , None          , [vara],     ([[]], v_bool_ty))
@@ -1624,15 +1625,16 @@ type TcGlobals(
   member val query_select_vref          = ValRefForIntrinsic v_query_select_value_info
   member val query_where_vref           = ValRefForIntrinsic v_query_where_value_info
   member val query_zero_vref            = ValRefForIntrinsic v_query_zero_value_info
-  member val seq_to_list_vref            = ValRefForIntrinsic v_seq_to_list_info
-  member val seq_to_array_vref            = ValRefForIntrinsic v_seq_to_array_info
+  member val seq_to_list_vref           = ValRefForIntrinsic v_seq_to_list_info
+  member val seq_to_array_vref          = ValRefForIntrinsic v_seq_to_array_info
 
   member _.seq_collect_info           = v_seq_collect_info
   member _.seq_using_info             = v_seq_using_info
   member _.seq_delay_info             = v_seq_delay_info
   member _.seq_append_info            = v_seq_append_info
   member _.seq_generated_info         = v_seq_generated_info
   member _.seq_finally_info           = v_seq_finally_info
+  member _.seq_trywith_info           = v_seq_trywith_info
   member _.seq_of_functions_info      = v_seq_of_functions_info
   member _.seq_map_info               = v_seq_map_info
   member _.seq_singleton_info         = v_seq_singleton_info

src/Compiler/TypedTree/TypedTreeOps.fs

@@ -7749,6 +7749,9 @@ let mkCallSeqGenerated g m elemTy arg1 arg2 =
 
 let mkCallSeqFinally g m elemTy arg1 arg2 = 
     mkApps g (typedExprForIntrinsic g m g.seq_finally_info, [[elemTy]], [ arg1; arg2 ], m) 
+
+let mkCallSeqTryWith g m elemTy origSeq exnFilter exnHandler = 
+    mkApps g (typedExprForIntrinsic g m g.seq_trywith_info, [[elemTy]], [ origSeq; exnFilter; exnHandler ], m) 
 
 let mkCallSeqOfFunctions g m ty1 ty2 arg1 arg2 arg3 = 
     mkApps g (typedExprForIntrinsic g m g.seq_of_functions_info, [[ty1;ty2]], [ arg1; arg2; arg3 ], m) 

src/Compiler/TypedTree/TypedTreeOps.fsi

@@ -2132,6 +2132,8 @@ val mkCallSeqAppend: TcGlobals -> range -> TType -> Expr -> Expr -> Expr
 
 val mkCallSeqFinally: TcGlobals -> range -> TType -> Expr -> Expr -> Expr
 
+val mkCallSeqTryWith: TcGlobals -> range -> TType -> Expr -> Expr -> Expr -> Expr
+
 val mkCallSeqGenerated: TcGlobals -> range -> TType -> Expr -> Expr -> Expr
 
 val mkCallSeqOfFunctions: TcGlobals -> range -> TType -> TType -> Expr -> Expr -> Expr -> Expr

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

@@ -382,11 +382,19 @@
         <target state="translated">reprezentace struktury aktivních vzorů</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Vyvolá upozornění, když se použije „let inline ... =“ společně s atributem [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. Funkce není vkládána.</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">Strukturdarstellung für aktive Muster</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Löst Warnungen aus, wenn „let inline ... =“ zusammen mit dem Attribut [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] verwendet wird. Die Funktion wird nicht inline gesetzt.</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">representación de struct para modelos activos</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Genera advertencias cuando se usa "let inline ... =" junto con el atributo [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. La función no se está insertando.</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">représentation de structure pour les modèles actifs</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Génère des avertissements lorsque « let inline ... = » est utilisé avec l’attribut [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. La fonction n’est pas inlined.</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">rappresentazione struct per criteri attivi</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">Genera avvisi quando 'let inline ... =' viene usato insieme all'attributo [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;]. La funzione non viene resa inline.</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">アクティブなパターンの構造体表現</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">'let inline ... =' が [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] 属性と一緒に使用されるときに警告を生成します。関数はインライン化されていません。</target>

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

@@ -382,11 +382,19 @@
         <target state="translated">활성 패턴에 대한 구조체 표현</target>
         <note />
       </trans-unit>
+
+      <trans-unit id="featureTryWithInSeqExpressions">
+        <source>Support for try-with in sequence expressions</source>
+        <target state="new">Support for try-with in sequence expressions</target>
+        <note />
+      </trans-unit>
+
       <trans-unit id="featureWarningWhenCopyAndUpdateRecordChangesAllFields">
         <source>Raises warnings when an copy-and-update record expression changes all fields of a record.</source>
         <target state="new">Raises warnings when an copy-and-update record expression changes all fields of a record.</target>
         <note />
       </trans-unit>
+
       <trans-unit id="featureWarningWhenInliningMethodImplNoInlineMarkedFunction">
         <source>Raises warnings when 'let inline ... =' is used together with [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] attribute. Function is not getting inlined.</source>
         <target state="translated">'let inline ... ='을(를) [&lt;MethodImpl(MethodImplOptions.NoInlining)&gt;] 특성과 함께 사용하는 경우 경고를 발생합니다. 함수가 인라인되지 않습니다.</target>