Files
gf-core/src-3.0/GF/Infra/PrintClass.hs

52 lines
1.5 KiB
Haskell

module GF.Infra.PrintClass where
import Data.List (intersperse)
class Print a where
prt :: a -> String
prtList :: [a] -> String
prtList as = "[" ++ prtSep "," as ++ "]"
prtSep :: Print a => String -> [a] -> String
prtSep sep = concat . intersperse sep . map prt
prtBefore :: Print a => String -> [a] -> String
prtBefore before = prtBeforeAfter before ""
prtAfter :: Print a => String -> [a] -> String
prtAfter after = prtBeforeAfter "" after
prtBeforeAfter :: Print a => String -> String -> [a] -> String
prtBeforeAfter before after as = concat [ before ++ prt a ++ after | a <- as ]
prtPairList :: (Print a, Print b) => String -> String -> [(a,b)] -> String
prtPairList comma sep xys = prtSep sep [ prt x ++ comma ++ prt y | (x,y) <- xys ]
prIO :: Print a => a -> IO ()
prIO = putStr . prt
instance Print a => Print [a] where
prt = prtList
instance (Print a, Print b) => Print (a, b) where
prt (a, b) = "(" ++ prt a ++ "," ++ prt b ++ ")"
instance (Print a, Print b, Print c) => Print (a, b, c) where
prt (a, b, c) = "(" ++ prt a ++ "," ++ prt b ++ "," ++ prt c ++ ")"
instance (Print a, Print b, Print c, Print d) => Print (a, b, c, d) where
prt (a, b, c, d) = "(" ++ prt a ++ "," ++ prt b ++ "," ++ prt c ++ "," ++ prt d ++ ")"
instance Print Char where
prt = return
prtList = id
instance Print Int where
prt = show
instance Print Integer where
prt = show
instance Print a => Print (Maybe a) where
prt (Just a) = prt a
prt Nothing = "Nothing"