Data.Digit.D4

Documentation

class D4 d where

Minimal complete definition

d4

Methods

d4 :: Prism' d ()

x4 :: d

Instances

D4 ()

Methods

d4 :: Prism' () ()

x4 :: ()

D4 Digit

Methods

d4 :: Prism' Digit ()

x4 :: Digit

parse4 :: (D4 d, CharParsing p) => p d

>>> parse (parse4 <* eof) "test" "4" :: Either ParseError Digit
Right 4

>>> parse parse4 "test" "4xyz" :: Either ParseError Digit
Right 4

>>> isn't _Right (parse parse4 "test" "xyz" :: Either ParseError Digit)
True 

\c -> c /= '4' ==> isn't _Right (parse parse4 "test" [c] :: Either ParseError Digit)