src/Tools/Haskell/Library.hs

more Haskell operations;

{- generated by Isabelle -}

{-  Title:      Tools/Haskell/Library.hs
    Author:     Makarius
    LICENSE:    BSD 3-clause (Isabelle)

Basic library of Isabelle idioms.
-}

module Isabelle.Library
  ((|>), (|->), (#>), (#->), the_default, fold, fold_rev, single, quote, trim_line)
where

import Data.Maybe


{- functions -}

(|>) :: a -> (a -> b) -> b
x |> f = f x

(|->) :: (a, b) -> (a -> b -> c) -> c
(x, y) |-> f = f x y

(#>) :: (a -> b) -> (b -> c) -> a -> c
(f #> g) x = x |> f |> g

(#->) :: (a -> (c, b)) -> (c -> b -> d) -> a -> d
(f #-> g) x  = x |> f |-> g


{- options -}

the_default :: a -> Maybe a -> a
the_default x Nothing = x
the_default _ (Just y) = y


{- lists -}

fold :: (a -> b -> b) -> [a] -> b -> b
fold _ [] y = y
fold f (x : xs) y = fold f xs (f x y)

fold_rev :: (a -> b -> b) -> [a] -> b -> b
fold_rev _ [] y = y
fold_rev f (x : xs) y = f x (fold_rev f xs y)

single :: a -> [a]
single x = [x]


{- strings -}

quote :: String -> String
quote s = "\"" ++ s ++ "\""

trim_line :: String -> String
trim_line line =
  case reverse line of
    '\n' : '\r' : rest -> reverse rest
    '\n' : rest -> reverse rest
    _ -> line