Re[2]: [Haskell-cafe] Bool as type class to serve EDSLs.

On Thu, 28 May 2009, Bulat Ziganshin wrote:

i use another approach which imho is somewhat closer to interpretation of logical operations in dynamic languages (lua, ruby, perl):

a ||| b | isDefaultValue a = b | otherwise = a

a &&& b | isDefaultValue a = defaultValue | otherwise = b

-- Class of types having default value: class Defaults a where defaultValue :: a instance Defaults () where defaultValue = () instance Defaults Bool where defaultValue = False instance Defaults [a] where defaultValue = []

The absence of such interpretations and thus the increased type safety was one of the major the reasons for me to move from scripting languages to Haskell.