From dab0e4b758ecc80439f2e40c4130635087b72b10 Mon Sep 17 00:00:00 2001
From: Gaith Hallak <gaithhallak@gmail.com>
Date: Sun, 30 Apr 2023 10:00:46 +0300
Subject: [PATCH] Move opposite_variance to type utils

---
 src/aeso_ast_infer_types.erl | 9 ++++-----
 src/aeso_tc_type_utils.erl   | 6 ++++++
 src/aeso_tc_unify.erl        | 7 ++++---
 3 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/src/aeso_ast_infer_types.erl b/src/aeso_ast_infer_types.erl
index 86b1269..260f6a8 100644
--- a/src/aeso_ast_infer_types.erl
+++ b/src/aeso_ast_infer_types.erl
@@ -124,6 +124,10 @@ unify(A, B, C, D) -> aeso_tc_unify:unify(A, B, C, D).
 unfold_types_in_type(A, B) -> aeso_tc_type_unfolding:unfold_types_in_type(A, B).
 unfold_record_types(A, B) -> aeso_tc_type_unfolding:unfold_record_types(A, B).
 
+%% -------
+
+opposite_variance(A) -> aeso_tc_type_utils:opposite_variance(A).
+
 %% -- The rest ---------------------------------------------------------------
 
 map_t(As, K, V) -> {app_t, As, {id, As, "map"}, [K, V]}.
@@ -510,11 +514,6 @@ infer_type_vars_variance({fun_t, _, [], Args, Res}) ->
     FlippedArgsVariance ++ ResVariance;
 infer_type_vars_variance(_) -> [].
 
-opposite_variance(invariant) -> invariant;
-opposite_variance(covariant) -> contravariant;
-opposite_variance(contravariant) -> covariant;
-opposite_variance(bivariant) -> bivariant.
-
 -spec check_constants(env(), [aeso_syntax:decl()]) -> {env(), [aeso_syntax:decl()]}.
 check_constants(Env, Consts) ->
     HasValidId = fun({letval, _, {id, _, _}, _})                -> true;
diff --git a/src/aeso_tc_type_utils.erl b/src/aeso_tc_type_utils.erl
index fbbaa60..9eebffb 100644
--- a/src/aeso_tc_type_utils.erl
+++ b/src/aeso_tc_type_utils.erl
@@ -7,6 +7,7 @@
         , fun_arity/1
         , ensure_first_order/2
         , ensure_monomorphic/2
+        , opposite_variance/1
         ]).
 
 typesig_to_fun_t({type_sig, Ann, _Constr, Named, Args, Res}) ->
@@ -80,3 +81,8 @@ is_first_order({fun_t, _, _, _, _})    -> false;
 is_first_order(Ts) when is_list(Ts)    -> lists:all(fun is_first_order/1, Ts);
 is_first_order(Tup) when is_tuple(Tup) -> is_first_order(tuple_to_list(Tup));
 is_first_order(_)                      -> true.
+
+opposite_variance(invariant) -> invariant;
+opposite_variance(covariant) -> contravariant;
+opposite_variance(contravariant) -> covariant;
+opposite_variance(bivariant) -> bivariant.
diff --git a/src/aeso_tc_unify.erl b/src/aeso_tc_unify.erl
index 045134a..45034ca 100644
--- a/src/aeso_tc_unify.erl
+++ b/src/aeso_tc_unify.erl
@@ -2,9 +2,6 @@
 
 -export([unify/4]).
 
-%% -- Circular dependency ----------------------------------------------------
-
-opposite_variance(A) -> aeso_ast_infer_types:opposite_variance(A).
 
 %% -- Moved functions --------------------------------------------------------
 
@@ -15,6 +12,10 @@ unfold_types_in_type(A, B, C) -> aeso_tc_type_unfolding:unfold_types_in_type(A,
 type_error(A) -> aeso_tc_errors:type_error(A).
 cannot_unify(A, B, C, D) -> aeso_tc_errors:cannot_unify(A, B, C, D).
 
+%% -------
+
+opposite_variance(A) -> aeso_tc_type_utils:opposite_variance(A).
+
 %% ---------------------------------------------------------------------------
 
 unify(Env, A, B, When) -> unify0(Env, A, B, covariant, When).