let-def / ppx_xmatch

Mess with the semantics of pattern matching :-)

ppx_xmatch

Mess with the semantics of pattern matching :-)

%resume extension

Allow to resume the execution of a pattern matching branch.

Add two new forms:

match%resume expr with
| pattern -> resumable_expr
| pattern when expr -> resumable_expr
| ..

function%resume
| pattern -> resumable_expr
| pattern when expr -> resumable_expr
| ..

A resumable_expr is an expression where [%resume] is allowed in a return position. In this case the control flow will jump to the next matching branch.

For instance:

let rec map_view view = function%resume
  | x :: rest ->
    begin match view x with
      | None -> [%resume]
      | Some x' -> x' :: list
    end
  | x :: rest -> x :: map_view view rest