Find earliest package version with function X

Question

So I'm sitting here wondering why the hell I can't find the function I'm looking for, and it turns out it doesn't exist in the version of the package I have installed.

So how do I make Hackage tell me what version that function was added in?

(In particular, so I can specify the correct package bounds in my Cabal description.)

Answer 1

hackage-diff is probably the tool you are looking for.

N.B. I never tried it myself.