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Overview
Comment:TypeChecker now checks to see if a multiword handles every possible leading type. Fixes [56a0fe1350].
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA3-256: dbcb88d2fc2f2f1cfb95b2ba0900515ac26cd1b979e8db95f5a2ddd37e96c294
User & Date: robin.hansen on 2020-10-23 04:46:29
Other Links: manifest | tags
Context
2020-11-19
05:57
Fix 'Quotations' example in play ground. check-in: fc5483d159 user: robin.hansen tags: trunk, alpha-1, releases
2020-11-17
14:42
Add test for compilation failure found in playground. check-in: d4ac6cbece user: robin.hansen tags: bugfix-generics-and-quotations
2020-10-23
04:46
TypeChecker now checks to see if a multiword handles every possible leading type. Fixes [56a0fe1350]... check-in: dbcb88d2fc user: robin.hansen tags: trunk
04:44
Add error message for inexhaustive multiwords. Closed-Leaf check-in: 30f96733db user: robin.hansen tags: exhaustiveness-checking
2020-10-13
05:00
Unions with generic branches can now be used in multiwords. Fixing [0dd72ccbb4]. check-in: 1fd01c7a22 user: robin.hansen tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Modified src/Play/TypeChecker.elm from [a76842cc9d] to [6269134213].

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        inferredType =
            List.head inferredWhenTypes
                |> Maybe.withDefault { input = [], output = [] }
                |> replaceFirstType (unionOfTypeMatches whens)
                |> joinOutputs (List.map .output inferredWhenTypes)























        finalContext =
            { newContext
                | typedWords =
                    Dict.insert untypedDef.name
                        { name = untypedDef.name
                        , type_ =
                            TypeSignature.toMaybe untypedDef.metadata.type_
                                |> Maybe.withDefault inferredType
                        , metadata = untypedDef.metadata
                        , implementation =
                            MultiImpl
                                (List.map (Tuple.mapBoth mapTypeMatch (untypedToTypedImplementation newContext)) initialWhens)
                                (untypedToTypedImplementation newContext defaultImpl)
                        }
                        newContext.typedWords
                , errors =
                    if whensAreConsistent && whensAreCompatible then
                        newContext.errors

                    else
                        let
                            error =
                                InconsistentWhens
                                    (Maybe.withDefault SourceLocation.emptyRange untypedDef.metadata.sourceLocationRange)
                                    untypedDef.name
                        in
                        error :: newContext.errors
            }
    in
    verifyTypeSignature inferredType untypedDef finalContext
        |> cleanContext


inferWhenTypes :
................................................................................

        Qualifier.LiteralType val ->
            ( fieldName, LiteralType val )

        Qualifier.RecursiveMatch val ->
            ( fieldName, RecursiveMatch (mapTypeMatch val) )






















































































verifyTypeSignature : WordType -> Qualifier.WordDefinition -> Context -> Context
verifyTypeSignature inferredType untypedDef context =
    case TypeSignature.toMaybe untypedDef.metadata.type_ of
        Just annotatedType ->
            let
                ( _, simplifiedAnnotatedType ) =







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        inferredType =
            List.head inferredWhenTypes
                |> Maybe.withDefault { input = [], output = [] }
                |> replaceFirstType (unionOfTypeMatches whens)
                |> joinOutputs (List.map .output inferredWhenTypes)

        exposedType =
            TypeSignature.toMaybe untypedDef.metadata.type_
                |> Maybe.withDefault inferredType

        maybeConsistencyError =
            if whensAreConsistent && whensAreCompatible then
                Nothing

            else
                let
                    error =
                        InconsistentWhens
                            (Maybe.withDefault SourceLocation.emptyRange untypedDef.metadata.sourceLocationRange)
                            untypedDef.name
                in
                Just error

        maybeInexhaustiveError =
            inexhaustivenessCheck
                (Maybe.withDefault SourceLocation.emptyRange untypedDef.metadata.sourceLocationRange)
                whenPatterns

        finalContext =
            { newContext
                | typedWords =
                    Dict.insert untypedDef.name
                        { name = untypedDef.name
                        , type_ = exposedType


                        , metadata = untypedDef.metadata
                        , implementation =
                            MultiImpl
                                (List.map (Tuple.mapBoth mapTypeMatch (untypedToTypedImplementation newContext)) initialWhens)
                                (untypedToTypedImplementation newContext defaultImpl)
                        }
                        newContext.typedWords
                , errors = List.filterMap identity [ maybeConsistencyError, maybeInexhaustiveError ] ++ newContext.errors











            }
    in
    verifyTypeSignature inferredType untypedDef finalContext
        |> cleanContext


inferWhenTypes :
................................................................................

        Qualifier.LiteralType val ->
            ( fieldName, LiteralType val )

        Qualifier.RecursiveMatch val ->
            ( fieldName, RecursiveMatch (mapTypeMatch val) )


inexhaustivenessCheck : SourceLocationRange -> List Qualifier.TypeMatch -> Maybe Problem
inexhaustivenessCheck range patterns =
    let
        inexhaustiveStates =
            List.foldl (inexhaustivenessCheckHelper []) [] patterns
                |> List.filter (\( _, state ) -> state /= Total)
                |> List.map Tuple.first
    in
    case inexhaustiveStates of
        [] ->
            Nothing

        _ ->
            Just (InexhaustiveMultiWord range inexhaustiveStates)


type InexhaustiveState
    = Total
    | SeenInt
    | SeenType Type


inexhaustivenessCheckHelper : List Type -> Qualifier.TypeMatch -> List ( List Type, InexhaustiveState ) -> List ( List Type, InexhaustiveState )
inexhaustivenessCheckHelper typePrefix (Qualifier.TypeMatch _ t conds) acc =
    let
        typeList =
            typePrefix ++ [ t ]
    in
    if List.any (\( toMatch, state ) -> typeList == toMatch && state == Total) acc then
        acc

    else
        let
            subcases =
                conds
                    |> List.map Tuple.second
                    |> List.filterMap isRecursiveMatch
                    |> List.foldl (inexhaustivenessCheckHelper typeList) acc

            isRecursiveMatch match =
                case match of
                    Qualifier.RecursiveMatch cond ->
                        Just cond

                    _ ->
                        Nothing

            toAdd =
                case ( t, conds, subcases ) of
                    ( _, [], _ ) ->
                        [ ( typeList, Total ) ]

                    ( Type.Int, _, _ ) ->
                        [ ( typeList, SeenInt ) ]

                    _ ->
                        if List.all (Tuple.second >> (==) Total) subcases then
                            [ ( typeList, Total ) ]

                        else
                            subcases

            modifiedAcc =
                if toAdd /= [ ( typeList, Total ) ] then
                    acc

                else
                    List.filter
                        (\( toMatch, _ ) ->
                            List.take (List.length typeList) toMatch /= typeList
                        )
                        acc
        in
        if List.find (\( toMatch, _ ) -> toMatch == typeList) modifiedAcc == Nothing then
            toAdd ++ modifiedAcc

        else
            let
                updatedStates =
                    List.filter (\( toMatch, _ ) -> toMatch /= typeList) modifiedAcc
            in
            toAdd ++ updatedStates


verifyTypeSignature : WordType -> Qualifier.WordDefinition -> Context -> Context
verifyTypeSignature inferredType untypedDef context =
    case TypeSignature.toMaybe untypedDef.metadata.type_ of
        Just annotatedType ->
            let
                ( _, simplifiedAnnotatedType ) =

Modified src/Play/TypeChecker/Problem.elm from [6e4a47646f] to [b183d4af4c].

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type Problem
    = UndeclaredGeneric SourceLocationRange String (Set String)
    | TypeError SourceLocationRange String WordType WordType
    | UnexpectedType SourceLocationRange String Type Type
    | InconsistentWhens SourceLocationRange String
    | MissingTypeAnnotationInRecursiveCallStack SourceLocationRange String



toString : String -> Problem -> String
toString source problem =
    case problem of
        UndeclaredGeneric range generic _ ->
            SourceLocation.extractFromString source range
................................................................................

        MissingTypeAnnotationInRecursiveCallStack range name ->
            SourceLocation.extractFromString source range
                ++ "\n\n"
                ++ "We require a type annotation for '"
                ++ name
                ++ "' as we're unable to infer the type of a recursive call."

















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type Problem
    = UndeclaredGeneric SourceLocationRange String (Set String)
    | TypeError SourceLocationRange String WordType WordType
    | UnexpectedType SourceLocationRange String Type Type
    | InconsistentWhens SourceLocationRange String
    | MissingTypeAnnotationInRecursiveCallStack SourceLocationRange String
    | InexhaustiveMultiWord SourceLocationRange (List (List Type))


toString : String -> Problem -> String
toString source problem =
    case problem of
        UndeclaredGeneric range generic _ ->
            SourceLocation.extractFromString source range
................................................................................

        MissingTypeAnnotationInRecursiveCallStack range name ->
            SourceLocation.extractFromString source range
                ++ "\n\n"
                ++ "We require a type annotation for '"
                ++ name
                ++ "' as we're unable to infer the type of a recursive call."

        InexhaustiveMultiWord range missingTypes ->
            let
                formatTypePattern tp =
                    String.join " -> " (List.map Type.toDisplayString tp)
            in
            SourceLocation.extractFromString source range
                ++ "\n\n"
                ++ "This multiword doesn't handle all potential patterns. Missing patterns for:\n\n"
                ++ String.join "\n" (List.map formatTypePattern missingTypes)

Modified tests/Test/TypeChecker/Error.elm from [2b38f63d66] to [6a887ebaba].

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                                { input = [ Type.Int ], output = [ Type.Union [ Type.Generic "b", Type.Generic "a" ] ] }
                                { input = [ Type.Int ], output = [ Type.Union [ Type.Custom "False", Type.Custom "True" ] ] }
                            ]
                            errors

                    Ok _ ->
                        Expect.fail "Did not expect type checking to succeed"








































































































































































































































































































































































        ]


checkForError : (Problem.Problem -> Bool) -> AST -> Expectation
checkForError fn source =
    case TypeChecker.run source of
        Err errors ->







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                                { input = [ Type.Int ], output = [ Type.Union [ Type.Generic "b", Type.Generic "a" ] ] }
                                { input = [ Type.Int ], output = [ Type.Union [ Type.Custom "False", Type.Custom "True" ] ] }
                            ]
                            errors

                    Ok _ ->
                        Expect.fail "Did not expect type checking to succeed"
        , describe "Inexhaustiveness checking"
            [ test "Simple example" <|
                \_ ->
                    let
                        ast =
                            { types = Dict.empty
                            , words =
                                Dict.fromListBy .name
                                    [ { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                      , implementation =
                                            SoloImpl
                                                [ Integer emptyRange 2
                                                , Word emptyRange "mword"
                                                ]
                                      }
                                    , { name = "mword"
                                      , metadata = Metadata.default
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 1 ) ]
                                                  , [ Integer emptyRange 1
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                ]
                                                []
                                      }
                                    ]
                            }

                        inexhaustiveError problem =
                            case problem of
                                Problem.InexhaustiveMultiWord _ [ [ Type.Int ] ] ->
                                    True

                                _ ->
                                    False
                    in
                    checkForError inexhaustiveError ast
            , test "Default clause is exhaustive" <|
                \_ ->
                    let
                        ast =
                            { types = Dict.empty
                            , words =
                                Dict.fromListBy .name
                                    [ { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                      , implementation =
                                            SoloImpl
                                                [ Integer emptyRange 2
                                                , Word emptyRange "mword"
                                                ]
                                      }
                                    , { name = "mword"
                                      , metadata = Metadata.default
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 1 ) ]
                                                  , [ Integer emptyRange 1
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                ]
                                                [ Integer emptyRange 0
                                                , Builtin emptyRange Builtin.Plus
                                                ]
                                      }
                                    ]
                            }
                    in
                    case TypeChecker.run ast of
                        Ok _ ->
                            Expect.pass

                        Err errs ->
                            Expect.fail <| "Failed for unexpected reason: " ++ Debug.toString errs
            , test "Nested" <|
                \_ ->
                    let
                        ast =
                            { types =
                                Dict.fromListBy typeDefinitionName
                                    [ CustomTypeDef "IntBox"
                                        emptyRange
                                        []
                                        [ ( "value", Type.Int ) ]
                                    ]
                            , words =
                                Dict.fromListBy .name
                                    [ { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                                |> Metadata.withType [] [ Type.Int ]
                                      , implementation =
                                            SoloImpl
                                                [ Integer emptyRange 1
                                                , Word emptyRange ">IntBox"
                                                , Word emptyRange "mword"
                                                , Word emptyRange "value>"
                                                ]
                                      }
                                    , { name = "mword"
                                      , metadata = Metadata.default
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange
                                                        (Type.Custom "IntBox")
                                                        [ ( "value>"
                                                          , RecursiveMatch
                                                                (TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 1 ) ])
                                                          )
                                                        ]
                                                  , [ Word emptyRange "value>"
                                                    , Integer emptyRange 1
                                                    , Builtin emptyRange Builtin.Plus
                                                    , Word emptyRange ">IntBox"
                                                    ]
                                                  )
                                                ]
                                                []
                                      }
                                    , { name = ">IntBox"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Int ] [ Type.Custom "IntBox" ]
                                      , implementation =
                                            SoloImpl
                                                [ ConstructType "IntBox" ]
                                      }
                                    , { name = ">value"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Custom "IntBox", Type.Int ] [ Type.Custom "IntBox" ]
                                      , implementation =
                                            SoloImpl
                                                [ SetMember "IntBox" "value" ]
                                      }
                                    , { name = "value>"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Custom "IntBox" ] [ Type.Int ]
                                      , implementation =
                                            SoloImpl
                                                [ GetMember "IntBox" "value" ]
                                      }
                                    ]
                            }

                        inexhaustiveError problem =
                            case problem of
                                Problem.InexhaustiveMultiWord _ [ [ Type.Custom "IntBox", Type.Int ] ] ->
                                    True

                                _ ->
                                    False
                    in
                    checkForError inexhaustiveError ast
            , test "A total branch should remove any earlier seen branch" <|
                \_ ->
                    let
                        ast =
                            { types = Dict.empty
                            , words =
                                Dict.fromListBy .name
                                    [ { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                      , implementation =
                                            SoloImpl
                                                [ Integer emptyRange 2
                                                , Word emptyRange "mword"
                                                ]
                                      }
                                    , { name = "mword"
                                      , metadata = Metadata.default
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 1 ) ]
                                                  , [ Integer emptyRange 1
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                , ( TypeMatch emptyRange Type.Int []
                                                  , [ Builtin emptyRange Builtin.StackDuplicate
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                ]
                                                []
                                      }
                                    ]
                            }
                    in
                    case TypeChecker.run ast of
                        Err errors ->
                            Expect.fail <| "Failed for unexpected reason: " ++ Debug.toString errors

                        Ok _ ->
                            Expect.pass
            , test "A total branch should prevent addition of later partial branch" <|
                \_ ->
                    let
                        ast =
                            { types = Dict.empty
                            , words =
                                Dict.fromListBy .name
                                    [ { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                      , implementation =
                                            SoloImpl
                                                [ Integer emptyRange 2
                                                , Word emptyRange "mword"
                                                ]
                                      }
                                    , { name = "mword"
                                      , metadata = Metadata.default
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange Type.Int []
                                                  , [ Builtin emptyRange Builtin.StackDuplicate
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                , ( TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 1 ) ]
                                                  , [ Integer emptyRange 1
                                                    , Builtin emptyRange Builtin.Plus
                                                    ]
                                                  )
                                                ]
                                                []
                                      }
                                    ]
                            }
                    in
                    case TypeChecker.run ast of
                        Err errors ->
                            Expect.fail <| "Failed for unexpected reason: " ++ Debug.toString errors

                        Ok _ ->
                            Expect.pass
            , test "Test with non-int type as pattern" <|
                \_ ->
                    let
                        maybeUnion =
                            Type.Union
                                [ Type.Custom "IntBox"
                                , Type.Custom "Nil"
                                ]

                        input =
                            { types =
                                Dict.fromListBy typeDefinitionName
                                    [ UnionTypeDef "Maybe"
                                        emptyRange
                                        [ "a" ]
                                        [ Type.Generic "a"
                                        , Type.Custom "Nil"
                                        ]
                                    , CustomTypeDef "IntBox"
                                        emptyRange
                                        []
                                        [ ( "value", Type.Int ) ]
                                    , CustomTypeDef "Nil" emptyRange [] []
                                    ]
                            , words =
                                Dict.fromListBy .name
                                    [ { name = ">Nil"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withType [] [ Type.Custom "Nil" ]
                                      , implementation =
                                            SoloImpl
                                                [ ConstructType "Nil"
                                                ]
                                      }
                                    , { name = ">IntBox"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Int ] [ Type.Custom "IntBox" ]
                                      , implementation =
                                            SoloImpl
                                                [ ConstructType "IntBox" ]
                                      }
                                    , { name = ">value"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Custom "IntBox", Type.Int ] [ Type.Custom "IntBox" ]
                                      , implementation =
                                            SoloImpl
                                                [ SetMember "IntBox" "value" ]
                                      }
                                    , { name = "value>"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withVerifiedType [ Type.Custom "IntBox" ] [ Type.Int ]
                                      , implementation =
                                            SoloImpl
                                                [ GetMember "IntBox" "value" ]
                                      }
                                    , { name = "with-default"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.withType
                                                    [ maybeUnion, Type.Int ]
                                                    [ Type.Int ]
                                      , implementation =
                                            MultiImpl
                                                [ ( TypeMatch emptyRange
                                                        (Type.Custom "IntBox")
                                                        [ ( "value>"
                                                          , RecursiveMatch <|
                                                                TypeMatch emptyRange Type.Int [ ( "value>", LiteralInt 0 ) ]
                                                          )
                                                        ]
                                                  , [ Builtin emptyRange Builtin.StackDrop
                                                    , Word emptyRange "value>"
                                                    ]
                                                  )
                                                , ( TypeMatch emptyRange (Type.Custom "Nil") []
                                                  , [ Builtin emptyRange Builtin.StackSwap
                                                    , Builtin emptyRange Builtin.StackDrop
                                                    ]
                                                  )
                                                ]
                                                []
                                      }
                                    , { name = "main"
                                      , metadata =
                                            Metadata.default
                                                |> Metadata.asEntryPoint
                                      , implementation =
                                            SoloImpl
                                                [ Word emptyRange ">Nil"
                                                , Integer emptyRange 1
                                                , Word emptyRange "with-default"
                                                ]
                                      }
                                    ]
                            }

                        inexhaustiveError problem =
                            case problem of
                                Problem.InexhaustiveMultiWord _ [ [ Type.Custom "IntBox", Type.Int ] ] ->
                                    True

                                _ ->
                                    False
                    in
                    checkForError inexhaustiveError input
            ]
        ]


checkForError : (Problem.Problem -> Bool) -> AST -> Expectation
checkForError fn source =
    case TypeChecker.run source of
        Err errors ->