GenericPretty

Memo

• Show と同等の Out という型クラスが定義されている

• 整形方法もカスタマイズ可能

使い方

Main.hs

{-# LANGUAGE DeriveGeneric #-}
import Text.PrettyPrint.GenericPretty

data Tree a
  = Leaf a
  | Fork (Tree a) (Tree a)
  deriving (Generic)

instance (Out a) => Out (Tree a)

t1, t2, t3, t4, t5 :: Tree Int
t5 = Fork t4 t4
t4 = Fork t3 t3
t3 = Fork t2 t2
t2 = Fork t1 t1
t1 = Fork t0 t0
t0 = Fork (Leaf 1) (Leaf 2)

ghci

λ stack repl --package GenericPretty
> :l Main.hs

> pp t1
Fork (Fork (Leaf 1) (Leaf 2))
     (Fork (Leaf 1) (Leaf 2))
     
> pp t2
Fork (Fork (Fork (Leaf 1) (Leaf 2))
           (Fork (Leaf 1) (Leaf 2)))
     (Fork (Fork (Leaf 1) (Leaf 2))
           (Fork (Leaf 1) (Leaf 2)))
           
> pp t3
Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                 (Fork (Leaf 1) (Leaf 2)))
           (Fork (Fork (Leaf 1) (Leaf 2))
                 (Fork (Leaf 1) (Leaf 2))))
     (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                 (Fork (Leaf 1) (Leaf 2)))
           (Fork (Fork (Leaf 1) (Leaf 2))
                 (Fork (Leaf 1) (Leaf 2))))
                 
> pp t4
Fork (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))
                 (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2))))
           (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))
                 (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))))
     (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))
                 (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2))))
           (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))
                 (Fork (Fork (Leaf 1) (Leaf 2))
                       (Fork (Leaf 1) (Leaf 2)))))
                       
> pp t5
Fork (Fork (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))
                 (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))))
           (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))
                 (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))))
     (Fork (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))
                 (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))))
           (Fork (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))
                 (Fork (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2)))
                       (Fork (Fork (Leaf 1) (Leaf 2))
                             (Fork (Leaf 1) (Leaf 2))))))

リソース

• RazvanRanca/GenericPretty

• GenericPretty on Hackage

• A generic deriving mechanism for Haskell