TypeInfo.hs

{-# LANGUAGE OverloadedStrings #-}

module Language.PureScript.Bridge.TypeInfo where


import Data.Text (Text)
import qualified Data.Text as T
import Data.Proxy
import Data.Typeable


-- Translates a Haskell type info to a PureScript type info:
type TypeBridge = TypeInfo -> Maybe TypeInfo


-- Basic info about a data type:
data TypeInfo = TypeInfo {
  -- | Hackage package
  typePackage :: !Text
  -- | Full Module path
, typeModule :: !Text
, typeName :: !Text
, typeParameters :: ![TypeInfo]
} deriving (Eq, Show)

mkTypeInfo :: Typeable t => Proxy t -> TypeInfo
mkTypeInfo = mkTypeInfo' . typeRep

mkTypeInfo' :: TypeRep -> TypeInfo
mkTypeInfo' rep = let
    con = typeRepTyCon rep
  in TypeInfo {
    typePackage = T.pack $ tyConPackage con
  , typeModule = T.pack $ tyConModule con
  , typeName = T.pack $ tyConName con
  , typeParameters = map mkTypeInfo' (typeRepArgs rep)
  }

-- | Put the TypeInfo in a list together with all its typeParameters (recursively)
flattenTypeInfo :: TypeInfo -> [TypeInfo]
flattenTypeInfo t = t : concatMap flattenTypeInfo (typeParameters t)

-- Little helper for type bridge implementers
eqTypeName :: Text -> TypeInfo -> Bool
eqTypeName name = (== name) . typeName