Rust part20

**デフォルトの名無しさん** · 2023/07/30(日) 10:57:59.43

>>860
Haskellではこうなります
https://ideone.com/PKy694

mysum [] = 0
mysum ( a : as ) = a + ( mysum as )

hogePlus a 0 = a
hogePlus a b | even b = 2 * (hogePlus a ( div b 2 ) )
hogePlus a b = 1 + 2 * (hogePlus a ( div b 2 ) )

data Hoge = H Integer deriving Show

instance Num Hoge where
( H x ) + ( H y ) = H ( hogePlus x y )
fromInteger = H

main = do
print $ mysum [ 1..5 ]
print $ hogePlus 3 7
print $ mysum [ H 1, H 3, H 7, H 15, H 31 ]