Created
April 15, 2017 17:56
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Invalid recursion in Elm 0.18 still causes runtime error
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| module ParseLibrary exposing (typeSignature) | |
| import Combine exposing (..) | |
| import Dict exposing (Dict) | |
| type Type | |
| = TArrow Type Type | |
| | TName String | |
| | TRecord (Dict String Type) | |
| typeSignature = | |
| lazy (\() -> | |
| sepBy (whitespace *> string "->" *> whitespace) nonFunctionType | |
| |> andThen (\list -> | |
| reducer TArrow list | |
| |> Maybe.map succeed | |
| |> Maybe.withDefault (fail "expected type, got nothing") | |
| ) | |
| ) | |
| reducer : (a -> a -> a) -> List a -> Maybe a | |
| reducer f list = | |
| case list of | |
| last :: [] -> | |
| Just last | |
| head :: tail -> | |
| reducer f tail | |
| |> Maybe.map (f head) | |
| [] -> | |
| Nothing | |
| nonFunctionType : Parser s Type | |
| nonFunctionType = | |
| lazy <| \() -> | |
| choice | |
| [ typeName | |
| , record | |
| ] | |
| typeName : Parser s Type | |
| typeName = | |
| TName <$> uppercaseName | |
| -- TODO: partial record | |
| record : Parser s Type | |
| record = | |
| (TRecord << Dict.fromList) <$> (string "{" *> commaSeparated recordItem <* string "}") | |
| recordItem : Parser a (String, Type) | |
| recordItem = | |
| (,) <$> lowercaseName <* string ":" <* whitespace <*> typeSignature | |
| commaSeparated : Parser s item -> Parser s (List item) | |
| commaSeparated = | |
| sepBy (string ",") | |
| alphanumericRe : String | |
| alphanumericRe = "[A-Za-z0-9]*" | |
| uppercaseName : Parser s String | |
| uppercaseName = | |
| whitespace *> regex ("[A-Z]" ++ alphanumericRe) <* whitespace | |
| lowercaseName : Parser s String | |
| lowercaseName = | |
| whitespace *> regex ("[a-z]" ++ alphanumericRe) <* whitespace |
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