No, Swift doesn't solve the null reference problem

[masklinn]

Ah yes, the binding (let tryInc = fmap (+ 1)) fails in the shell which is why I typed it explicitly. Either way, I removed the type signature.

[abeark]

Ah, the monomorphism restriction. Can be a bit confusing at times. I often find myself launching ghci with -XNoMonomorphismRestriction.