[RFC FS-1001] String Interpolation

src/fsharp/CheckFormatStrings.fsi

@@ -9,9 +9,10 @@ module internal FSharp.Compiler.CheckFormatStrings
 
 open FSharp.Compiler 
 open FSharp.Compiler.NameResolution
+open FSharp.Compiler.Range
 open FSharp.Compiler.TypedTree 
 open FSharp.Compiler.TcGlobals
 
-val ParseFormatString : Range.range -> TcGlobals -> formatStringCheckContext: FormatStringCheckContext option -> fmt: string -> bty: TType -> cty: TType -> dty: TType -> (TType * TType) * (Range.range * int) list
+val ParseFormatString : m: range -> fragmentRanges: range list -> g: TcGlobals -> isInterpolated: bool -> isFormattableString: bool -> formatStringCheckContext: FormatStringCheckContext option -> fmt: string -> bty: TType -> cty: TType -> dty: TType -> TType list * TType * TType * TType[] * (range * int) list * string
 
-val TryCountFormatStringArguments : m:Range.range -> g:TcGlobals -> fmt:string -> bty:TType -> cty:TType -> int option
+val TryCountFormatStringArguments: m: range -> g: TcGlobals -> isInterpolated: bool -> fmt:string -> bty:TType -> cty:TType -> int option

src/fsharp/CompileOps.fs

@@ -1166,6 +1166,10 @@ let OutputPhasedErrorR (os: StringBuilder) (err: PhasedDiagnostic) (canSuggestNa
               | Parser.TOKEN_EOF -> getErrorString("Parser.TOKEN.EOF")
               | Parser.TOKEN_CONST -> getErrorString("Parser.TOKEN.CONST")
               | Parser.TOKEN_FIXED -> getErrorString("Parser.TOKEN.FIXED")
+              | Parser.TOKEN_INTERP_STRING_BEGIN_END -> getErrorString("Parser.TOKEN.INTERP.STRING.BEGIN.END")
+              | Parser.TOKEN_INTERP_STRING_BEGIN_PART -> getErrorString("Parser.TOKEN.INTERP.STRING.BEGIN.PART")
+              | Parser.TOKEN_INTERP_STRING_PART -> getErrorString("Parser.TOKEN.INTERP.STRING.PART")
+              | Parser.TOKEN_INTERP_STRING_END -> getErrorString("Parser.TOKEN.INTERP.STRING.END")
               | unknown ->           
                   Debug.Assert(false, "unknown token tag")
                   let result = sprintf "%+A" unknown
@@ -3588,13 +3592,13 @@ let ParseOneInputLexbuf (tcConfig: TcConfig, lexResourceManager, conditionalComp
     use unwindbuildphase = PushThreadBuildPhaseUntilUnwind BuildPhase.Parse
     try 
         let skip = true in (* don't report whitespace from lexer *)
-        let lightSyntaxStatus = LightSyntaxStatus (tcConfig.ComputeLightSyntaxInitialStatus filename, true) 
-        let lexargs = mkLexargs (filename, conditionalCompilationDefines@tcConfig.conditionalCompilationDefines, lightSyntaxStatus, lexResourceManager, [], errorLogger, tcConfig.pathMap)
+        let lightStatus = LightSyntaxStatus (tcConfig.ComputeLightSyntaxInitialStatus filename, true) 
+        let lexargs = mkLexargs (conditionalCompilationDefines@tcConfig.conditionalCompilationDefines, lightStatus, lexResourceManager, [], errorLogger, tcConfig.pathMap)
         let shortFilename = SanitizeFileName filename tcConfig.implicitIncludeDir 
         let input = 
             Lexhelp.usingLexbufForParsing (lexbuf, filename) (fun lexbuf ->
                 if verbose then dprintn ("Parsing... "+shortFilename)
-                let tokenizer = LexFilter.LexFilter(lightSyntaxStatus, tcConfig.compilingFslib, Lexer.token lexargs skip, lexbuf)
+                let tokenizer = LexFilter.LexFilter(lightStatus, tcConfig.compilingFslib, Lexer.token lexargs skip, lexbuf)
 
                 if tcConfig.tokenizeOnly then 
                     while true do 

src/fsharp/ErrorLogger.fs

@@ -702,4 +702,9 @@ let internal tryLanguageFeatureErrorRecover langVersion langFeature m =
     | None -> ()
 
 let internal tryLanguageFeatureErrorOption langVersion langFeature m =
-    tryLanguageFeatureErrorAux langVersion langFeature m 
+    tryLanguageFeatureErrorAux langVersion langFeature m
+
+let internal languageFeatureNotSupportedInLibraryError (langVersion: LanguageVersion) (langFeature: LanguageFeature) (m: range) =
+    let featureStr = langVersion.GetFeatureString langFeature
+    let suggestedVersionStr = langVersion.GetFeatureVersionString langFeature
+    error (Error(FSComp.SR.chkFeatureNotSupportedInLibrary(featureStr, suggestedVersionStr), m))

src/fsharp/FSComp.txt

@@ -1490,6 +1490,7 @@ notAFunctionButMaybeDeclaration,"This value is not a function and cannot be appl
 3350,chkFeatureNotLanguageSupported,"Feature '%s' is not available in F# %s. Please use language version %s or greater."
 3351,chkFeatureNotRuntimeSupported,"Feature '%s' is not supported by target runtime."
 3352,typrelInterfaceMemberNoMostSpecificImplementation,"Interface member '%s' does not have a most specific implementation."
+3353,chkFeatureNotSupportedInLibrary,"Feature '%s' requires the F# library for language version %s or greater."
 useSdkRefs,"Use reference assemblies for .NET framework references when available (Enabled by default)."
 optsLangVersion,"Display the allowed values for language version, specify language version such as 'latest' or 'preview'"
 optsSupportedLangVersions,"Supported language versions:"
@@ -1509,11 +1510,27 @@ featureFixedIndexSlice3d4d,"fixed-index slice 3d/4d"
 featureAndBang,"applicative computation expressions"
 featureNullableOptionalInterop,"nullable optional interop"
 featureDefaultInterfaceMemberConsumption,"default interface member consumption"
+featureStringInterpolation,"string interpolation"
 featureWitnessPassing,"witness passing for trait constraints in F# quotations"
 3353,fsiInvalidDirective,"Invalid directive '#%s %s'"
 3360,typrelInterfaceWithConcreteAndVariable,"'%s' cannot implement the interface '%s' with the two instantiations '%s' and '%s' because they may unify."
 3361,typrelInterfaceWithConcreteAndVariableObjectExpression,"You cannot implement the interface '%s' with the two instantiations '%s' and '%s' because they may unify."
 featureInterfacesWithMultipleGenericInstantiation,"interfaces with multiple generic instantiation"
 3362,tcLiteralFieldAssignmentWithArg,"Cannot assign '%s' to a value marked literal"
 3363,tcLiteralFieldAssignmentNoArg,"Cannot assign a value to another value marked literal"
+forFormatInvalidForInterpolated,"Interpolated strings may not use '%%' format specifiers unless each is given an expression, e.g. '%%d{{1+1}}'."
+forFormatInvalidForInterpolated2,".NET-style format specifiers such as '{{x,3}}' or '{{x:N5}}' may not be mixed with '%%' format specifiers."
+forFormatInvalidForInterpolated3,"The '%%P' specifier may not be used explicitly."
+forFormatInvalidForInterpolated4,"Interpolated strings used as type IFormattable or type FormattableString may not use '%%' specifiers, only .NET-style interpolands such as '{{expr}}', '{{expr,3}}' or '{{expr:N5}}' may be used."
+3371,tcInterpolationMixedWithPercent,"Mismatch in interpolated string. Interpolated strings may not use '%%' format specifiers unless each is given an expression, e.g. '%%d{{1+1}}'"
+3372,tcInvalidAlignmentInInterpolatedString,"Invalid alignment in interpolated string"
+3373,lexSingleQuoteInSingleQuote,"Invalid interpolated string. Single quote or verbatim string literals may not be used in interpolated expressions in single quote or verbatim strings. Consider using an explicit 'let' binding for the interpolation expression or use a triple quote string as the outer string literal."
+3374,lexTripleQuoteInTripleQuote,"Invalid interpolated string. Triple quote string literals may not be used in interpolated expressions. Consider using an explicit 'let' binding for the interpolation expression."
+3376,tcUnableToParseInterpolatedString,"Invalid interpolated string. %s"
+3377,lexByteStringMayNotBeInterpolated,"a byte string may not be interpolated"
+3378,parsEofInInterpolatedStringFill,"Incomplete interpolated string expression fill begun at or before here"
+3379,parsEofInInterpolatedString,"Incomplete interpolated string begun at or before here"
+3380,parsEofInInterpolatedVerbatimString,"Incomplete interpolated verbatim string begun at or before here"
+3381,parsEofInInterpolatedTripleQuoteString,"Incomplete interpolated triple-quote string begun at or before here"
+3382,lexRBraceInInterpolatedString,"A '}}' character must be escaped (by doubling) in an interpolated string."
 #3501   "This construct is not supported by your version of the F# compiler" CompilerMessage(ExperimentalAttributeMessages.NotSupportedYet, 3501, IsError=true)

src/fsharp/FSStrings.resx

@@ -441,6 +441,18 @@
   <data name="Parser.TOKEN.FIXED" xml:space="preserve">
     <value>keyword 'fixed'</value>
   </data>
+  <data name="Parser.TOKEN.INTERP.STRING.BEGIN.END" xml:space="preserve">
+    <value>interpolated string</value>
+  </data>
+  <data name="Parser.TOKEN.INTERP.STRING.BEGIN.PART" xml:space="preserve">
+    <value>interpolated string (first part)</value>
+  </data>
+  <data name="Parser.TOKEN.INTERP.STRING.PART" xml:space="preserve">
+    <value>interpolated string (part)</value>
+  </data>
+  <data name="Parser.TOKEN.INTERP.STRING.END" xml:space="preserve">
+    <value>interpolated string (final part)</value>
+  </data>
   <data name="Parser.TOKEN.CONSTRAINT" xml:space="preserve">
     <value>keyword 'constraint'</value>
   </data>