Proxy arguments in class methods: a comparative analysis - Ryan Scott

The Foreign.Storable module provides a Storable class with two rather unusual methods: class Storable a where sizeOf :: a -> Int alignment :: a -> Int ... What is unusual about sizeOf and alignment? To demonstrate, consider what happens if we look up the sizes of various Int8s: λ> sizeOf (0 :: Int8) 1 λ> sizeOf (1 :: Int8) 1 λ> sizeOf (2 :: Int8) 1 λ> all (\c -> sizeOf c == 1) [minBound..maxBound

[lotz84]

型の情報しか使わない型クラスのメソッドをどうデザインするのが良いのか