[Haskell-cafe] adjoint of coproduct & diagonal

Jason Dusek jason.dusek at gmail.com
Sun Aug 3 13:01:12 EDT 2008

Derek Elkins <derek.a.elkins at gmail.com> wrote:
> The notation f+g is the notation for the functorial action of
> + : CxC -> C on arrows, that is, if f : A -> B and g : C -> D
> then f+g : A+C -> B+D.

  So [f,g] and f+g different. I assumed that the functorial
  action of + on arrows was to take ((A -> C), (B -> C)) to
  A+B -> C, which goes a long way to explaining my confusion :)


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