2015-10-01 11:01 GMT+02:00 Oliver Charles
[...] However, it's a lot more significant if you want to do something like:
foo x = doSomething (case x of ...)
Without pattern synonyms, you either have
foo x = doSomething x' where x' | x == ... = ...
or
{-# LANGUAGE MultiWayIf #-}
foo x = doSomething (if | x == ... -> ...)
Or simply in plain old Haskell (basically the desugaring of the multi-way-if): foo x = doSomething (case () of _ | x == gl_BAR -> expr1 | x == gl_BAZ -> expr2 | otherwise -> expr3) Compared to: foo x = doSomething (case x of GL_BAR -> expr1 GL_BAZ -> expr2 _ .> expr3) it doesn't really look *that* much different IMHO, given the high price one has to pay for a tiny improvement in readability. But that's my personal, more conservative view of things, and I'm here to see what other people prefer.Alas, up to now, this is not very conclusive... :-/