Language/LOL/Symantic/AST.hs

   1 {-# LANGUAGE Rank2Types #-}
   2 module Language.LOL.Symantic.AST where
   3
   4 import Data.Text (Text)
   5 import qualified Data.Text as Text
   6
   7 -- * Type 'AST'
   8
   9 -- | Abstract Syntax Tree.
  10 data AST
  11  =   AST Text [AST]
  12  deriving (Eq, Show)
  13
  14 -- * Type 'Error_Read'
  15
  16 data Error_Read
  17  =   Error_Read Text
  18  deriving (Eq, Show)
  19
  20 read_safe :: Read a => Text -> Either Error_Read a
  21 read_safe t =
  22         case reads $ Text.unpack t of
  23          [(x, "")] -> Right x
  24          _         -> Left $ Error_Read t