[aninhumer]

No one would ever write the latter, because (\p -> isValid p) is equivalent to isValid.

However you're right that the function names would probably be a little longer in practice, and I've edited my example to reflect that. (But they're not convenience functions, they just have longer names due to Haskell's more limited namespacing)

[junke]

Not a Haskell expert, but maybe monomorphism restriction can require you to perform an eta abstraction. Just saying.