@@ -1,5 +1,5 @@
11{-# LANGUAGE TypeFamilies #-}
2−{-# LANGUAGE ConstraintKinds #-}
2+{-# LANGUAGE MultiParamTypeClasses #-}
33{- |
44Module : Data.Syntax.Char
55Description : Char specific combinators.
@@ -14,7 +14,7 @@ Common combinators that work with sequences of chars.
1414There are A LOT of combinators missing.
1515-}
1616module Data.Syntax.Char (
17− SyntaxChar,
17+ SyntaxChar(..),
1818 spaces,
1919 spaces_,
2020 spaces1,
@@ -26,12 +26,23 @@ import Control.Lens.SemiIso
2626import Data.Char
2727import Data.MonoTraversable
2828import Data.Monoid
29+import Data.Scientific (Scientific)
2930import Data.SemiIsoFunctor
3031import Data.Syntax (Syntax)
3132import qualified Data.Syntax as S
3233
3334-- | Syntax constrainted to sequences of chars.
34−type SyntaxChar syn seq = (Syntax syn seq, Element seq ~ Char)
35+--
36+-- Note: methods of this class do not have default implementations (for now),
37+-- because their code is quite ugly and already written in most parser libraries.
38+class (Syntax syn seq, Element seq ~ Char) => SyntaxChar syn seq where
39+ -- | An unsigned decimal number.
40+ decimal :: Integral a => syn a
41+
42+ -- | A scientific number.
43+ scientific :: syn Scientific
44+
45+ {-# MINIMAL decimal, scientific #-}
3546
3647-- | Accepts zero or more spaces. Generates a single space.
3748spaces :: SyntaxChar syn seq => syn ()