fact: Definition usual_callcc r (M := fun C => (C -> r) -> r) A B (f : (A -> M B) -> M A) : M A := fun k : A -> r => f (fun a _ => k a) k.
imports: mathcomp(all_ssreflect) imonae_lib HB(structures) ihierarchy imonad_lib ifail_lib istate_lib itrace_lib imonad_transformer