module Language.PureScript.Parser.Types (
parseType,
parsePolyType,
noWildcards,
parseTypeAtom
) where
import Control.Applicative
import Control.Monad (when, unless)
import Language.PureScript.Types
import Language.PureScript.Parser.Common
import Language.PureScript.Parser.Kinds
import Language.PureScript.Parser.Lexer
import Language.PureScript.Environment
import qualified Text.Parsec as P
import qualified Text.Parsec.Expr as P
parseFunction :: TokenParser Type
parseFunction = parens rarrow >> return tyFunction
parseObject :: TokenParser Type
parseObject = braces $ TypeApp tyObject <$> parseRow
parseTypeWildcard :: TokenParser Type
parseTypeWildcard = underscore >> return TypeWildcard
parseTypeVariable :: TokenParser Type
parseTypeVariable = do
ident <- identifier
when (ident `elem` reservedTypeNames) $ P.unexpected ident
return $ TypeVar ident
parseTypeConstructor :: TokenParser Type
parseTypeConstructor = TypeConstructor <$> parseQualified properName
parseForAll :: TokenParser Type
parseForAll = mkForAll <$> ((reserved "forall" <|> reserved "∀") *> P.many1 (indented *> identifier) <* indented <* dot)
<*> parseType
parseTypeAtom :: TokenParser Type
parseTypeAtom = indented *> P.choice
[ P.try parseConstrainedType
, P.try parseFunction
, parseObject
, parseTypeWildcard
, parseForAll
, parseTypeVariable
, parseTypeConstructor
, P.try (parens parseRow)
, parens parsePolyType
]
parseConstrainedType :: TokenParser Type
parseConstrainedType = do
constraints <- P.try (return <$> parseConstraint) <|> parens (commaSep1 parseConstraint)
_ <- rfatArrow
indented
ty <- parseType
return $ ConstrainedType constraints ty
where
parseConstraint = do
className <- parseQualified properName
indented
ty <- P.many parseTypeAtom
return (className, ty)
parseAnyType :: TokenParser Type
parseAnyType = P.buildExpressionParser operators (buildPostfixParser postfixTable parseTypeAtom) P.<?> "type"
where
operators = [ [ P.Infix (return TypeApp) P.AssocLeft ]
, [ P.Infix (rarrow >> return function) P.AssocRight ]
]
postfixTable = [ \t -> KindedType t <$> (indented *> doubleColon *> parseKind)
]
parseType :: TokenParser Type
parseType = do
ty <- parseAnyType
unless (isMonoType ty) $ P.unexpected "polymorphic type"
return ty
parsePolyType :: TokenParser Type
parsePolyType = parseAnyType
noWildcards :: TokenParser Type -> TokenParser Type
noWildcards p = do
ty <- p
when (containsWildcards ty) $ P.unexpected "type wildcard"
return ty
parseNameAndType :: TokenParser t -> TokenParser (String, t)
parseNameAndType p = (,) <$> (indented *> (lname <|> stringLiteral) <* indented <* doubleColon) <*> p
parseRowEnding :: TokenParser Type
parseRowEnding = P.option REmpty $ indented *> pipe *> indented *> parseType
parseRow :: TokenParser Type
parseRow = (curry rowFromList <$> commaSep (parseNameAndType parsePolyType) <*> parseRowEnding) P.<?> "row"