Definition. Kleisli category of a promonad [mde-0008]

Let \((T, \eta , \mu )\) be a promonad on a category \(ℂ\). Its Kleisli category \(\textsf {kl}(T)\) has

  • Objects: those of \(ℂ\)
  • Morphisms: \(\textsf {kl}(T)(A;B) := T(A;B)\)
  • Identities: given by \(\eta _{A,A}(\textsf {id}_{A})\)
  • Composition: given by \(\mu \).

Note that when \(T\) is a representable profunctor, i.e. \(T(A;B) = ℂ(A; FB)\) for some functor \(F\), this is just the usual Kleisli category for a monad.