Christian Maeder wrote:
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
Having notElem is needed for those of us who have a different opinion of using infix notation (which is big part of Haskell's syntactic sugar compared to Scheme). Adding to a library is a matter of balance: is there name clear or ambiguous? is it being added because it is wanted or speculatively? In this case there seems to be one clear meaning to the name "notElem" and there are users who actually want it. So "notElem" and "notMember" are both good things to put in the library. -- Chris