[Haskell-cafe] how do I avoid excessive constructor application?
S. Alexander Jacobson
alex at alexjacobson.com
Tue Mar 1 21:52:59 EST 2005
For some reason, these two functions have different types.
fun1 f (Left x)= Left (f x)
fun1 _ r@(Right x) = Right x
fun2 f (Left x) = Left (f x)
fun2 _ r = r
Is there a way to rewrite fun2 so that f has type (a->b)?
In the general case, it seems wasteful to have to destruct and
construct values just for type checking reasons, especially if your
type has many more constructors than (Either a b).
S. Alexander Jacobson tel:917-770-6565 http://alexjacobson.com
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