Cale Gibbard wrote:
I don't like notElem either
* quite useful for cleaning up guards:
f x | not (x `Set.member` map) && foo = ... is hard to read.
I think the plain application "not (Set.member x map) && foo" is more appropriate for a programming language like haskell with a somewhat limited support of mathematical notations (i.e. not postfix applications).
Although I'd normally agree with negated versions of things being somewhat redundant, the infix version here is rather important, since one often wants the code to look the same way as the mathematics. The symbols \in and \not\in are both usually written infix, and that's not going to change soon.
latex does not have to consider precedences and the latex sources also look much less nice than the final printed version. Christian