Ternary operator

Categories: Code | Idioms

With a bit of work, we can define a ternary conditional operator in Haskell. Courtesy of Andrew Baumann. This appears only to be valid in Hugs?

import qualified Prelude
 
data Cond a = a : a
 
infixl 0 ?
infixl 1 :
 
(?) :: Prelude.Bool -> Cond a -> a
Prelude.True  ? (x : _) = x
Prelude.False ? (_ : y) = y
 
test = 1 Prelude.< 2 ? "yeah" : "no!"

Further reading

• Rebindable syntax
• Techniques for Embedding Postfix Languages in Haskell

Recent content is available under a simple permissive license.