Hi David,
A let clause would work fine here:
someFunction ls a b c = let listLen = length ls someAuxFunction x y = ... listLen ... someOtherFunction x y = ... listLen ... in ... listLen ...
it's just that you don't want to mix let and where clauses, because then things get confusing. Even if it worked with both, noone would know the binding rules.
Possibly in that case, but there are cases where I believe they are not the same. For example: gg n = ([1..,10^6*n], [1..10^6*n]) exp = (fst $ gg 1000, snd $ gg 1000) this could be captured nicely in a where clause: exp = (fst blah, snd blah) where blah = gg 1000 But a let would have to be placed in both elements of the tuple - and therefore being evaluated twice (unless the implementation is smart enough to work out they can be shared?): exp = (let blah = g 1000 in fst blah, let blah = g 1000 in snd blah) Kind regards, Chris.