Commit 2c2c4632 authored by Mário Pereira's avatar Mário Pereira

Refinement (wip)

A good example is worth a thousand words:

module Sig
  type t = private mutable {}

  val f (t: t) : int
    writes { t }
end

module Impl
  use import int.Int

  type t = { mutable size: int }

  let f (t: t) : int
    writes  { t }
    ensures { result = (old t).size }
    ensures { t.size = (old t).size + 1 }
  = let x = t.size in t.size <- t.size + 1;
    x

  clone Sig with type t = t, val f = f
end

In order for this clone to succeed, we need to add the field
[size] to the [writes] of the cloned val [f].
In the general case, we add all of the new mutable fields of
a refinement type to [writes] clause of the cloned function
(even if their values are not changed by the function execution).

FIXME: fix the case in which the type to be refined is already
declared with some mutable fields.
parent 52a56bb5
......@@ -774,8 +774,16 @@ let clone_cty cl sm ?(drop_decr=false) cty =
let reads = Spv.union reads (Mpv.domain olds) in
let add_write reg fs m =
let add_fd fd s = Spv.add (Mpv.find_def fd fd cl.fd_table) s in
Mreg.add (clone_reg cl reg) (Spv.fold add_fd fs Spv.empty) m in
let reg' = Mreg.find_def reg reg cl.rn_table in
let smf_reg' = Spv.of_list reg'.reg_its.its_mfields in
let smf_reg = Spv.of_list reg.reg_its.its_mfields in
let smf_diff = Spv.diff smf_reg' smf_reg in
let fs = Spv.fold add_fd fs Spv.empty in
Mreg.add (clone_reg cl reg) (Spv.union fs smf_diff) m in
let writes = Mreg.fold add_write cty.cty_effect.eff_writes Mreg.empty in
(* Mreg.iter (fun rho spv -> Format.eprintf "rho:%a@." print_reg rho; *)
(* Spv.iter (fun pv -> Format.eprintf "pv:%a@." print_pv pv) spv) *)
(* writes; *)
let add_reset reg s = Sreg.add (clone_reg cl reg) s in
let resets = Sreg.fold add_reset cty.cty_effect.eff_resets Sreg.empty in
let eff = eff_reset (eff_write reads writes) resets in
......
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