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Created by Dan Frumin@dfruminContributor

`wp_binop` is not very useful for comparing arbitrary values

Consider the following piece of code:

From iris.heap_lang Require Export proofmode notation.

Lemma wut `{heapG Σ} (v1 v2 : val) :
  (WP if: (v1 = v2) then #0 else #0 {{ _, True }})%I.
Proof.
  wp_binop.
Abort.

The goal that I expected after executing wp_binop:

WP if: #(bool_decide (v1 = v2)) then #0 else #0 {{ _, True }}

Instead I got two goals:

  • bin_op_eval EqOp v1 v2 = Some ?Goal0
  • WP if: ?Goal0 then #0 else #0 {{ _, True }}

This is not very helpful, as it is pretty annoying to get a boolean value for ?Goal0.

I believe this is due to the way that bin_op_eval is defined: it first matches v1 and v2 for specific types of values (integers or booleans), and only then considers the case of generalized equality checks.

Since we have generalized/dynamic equality checks in heap_lang, why not first match on the type of the operation, and only then match on the values in bin_op_eval?

Best -Dan