Re: darcs patch: add Data.Set.notMember and Data.Map.notMember

John Meacham wrote:

On Thu, Mar 09, 2006 at 11:09:50PM +0100, Jean-Philippe Bernardy wrote: [...]

...

Any evidence to add to the case ?

* symmetry with elem/notElem

I don't like notElem either

* quite useful for cleaning up guards:

f x | not (x `Set.member` map) && foo = ... is hard to read.

You may swap quards (or the "then" and "else" branches of "if"), or avoid the infix notation (which is horrible in this case anyway). I don't think we need negated versions of any boolean function, that's what "not" is for! Christian