Add FirstOrDefault() with a predicate (merged Where and FirstOrDefault())

[FredTunaB]

So we could do this:
int val = list.Gen().FirstOrDefault(/*predicate*/)

insead of

int val = list.Gen().Where(/*predicate/*).FirstOrDefault()

[donitry]

but i use list.Gen().FirstOrDefault(/predicate/) fail, always to use int val = list.Gen().Where(/predicate/).FirstOrDefault().... why??

[donitry]

when can use "TakeWhile" ???