[Haskell-cafe] adjoint of coproduct & diagonal

I'm trying to figure out the adjunction diagrams for the adjunction where the diagonal functor is right adjoint to the coproduct functor. I'm |almost done|, but the co-unit has me stumped, because I can't figure out how the arrow at the top can be unique -- it seems it could be either one of: i_1 . [f,g] i_2 . [f,g] i_1, i_2 : C -> C+C f : A -> C g : B -> C The net effect of [id,id] on the right is to blur out the distinction. On #haskell, someone suggested there is a constraint I am missing; I've poked around for a day and still can't figure it out. -- _jsn |almost done| http://hpaste.org/9303