diff options
| -rw-r--r-- | engine/logic_monad.ml | 8 | ||||
| -rw-r--r-- | engine/logic_monad.mli | 7 |
2 files changed, 15 insertions, 0 deletions
diff --git a/engine/logic_monad.ml b/engine/logic_monad.ml index 79bf48acdd..c88de133d4 100644 --- a/engine/logic_monad.ml +++ b/engine/logic_monad.ml @@ -215,6 +215,14 @@ struct let modify f = { iolist = fun s nil cons -> cons () (f s) nil } + (** Exception manipulation *) + + let interleave src dst m = + { iolist = fun s nil cons -> + m.iolist s (fun e1 -> nil (src e1)) + (fun x s next -> cons x s (fun e2 -> next (dst e2))) + } + (** List observation *) let once m = diff --git a/engine/logic_monad.mli b/engine/logic_monad.mli index 42e49d5a7e..1869f32633 100644 --- a/engine/logic_monad.mli +++ b/engine/logic_monad.mli @@ -115,6 +115,13 @@ module BackState : sig val get : ('s, 's, 's, 'e) t val modify : ('i -> 'o) -> (unit, 'i, 'o, 'e) t + val interleave : ('e1 -> 'e2) -> ('e2 -> 'e1) -> ('a, 'i, 'o, 'e1) t -> + ('a, 'i, 'o, 'e2) t + (** [interleave src dst m] adapts the exceptional content of the monad + according to the functions [src] and [dst]. To ensure a meaningful result, + those functions must form a retraction, i.e. [dst (src e1) = e1] for all + [e1]. This is typically the case when the type ['e1] is [unit]. *) + val zero : 'e -> ('a, 'i, 'o, 'e) t val plus : ('a, 'i, 'o, 'e) t -> ('e -> ('a, 'i, 'o, 'e) t) -> ('a, 'i, 'o, 'e) t |