SCP-5126 Added note on invariants in unpack and repacking AssocMap.

input-output-hk · Mar 1, 2023 · e227767 · e227767
1 parent c288060
commit e227767
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/marlowe/src/Language/Marlowe/Core/V1/Semantics.hs b/marlowe/src/Language/Marlowe/Core/V1/Semantics.hs
@@ -523,7 +523,9 @@ refundOne accounts = case Map.toList accounts of
     -- SCP-5126: The return value of this function differs from
     -- Isabelle semantics in that it returns the least-recently
     -- added account-token combination rather than the first
-    -- lexicographically ordered one.
+    -- lexicographically ordered one. Also, the sequence
+    -- `Map.fromList . tail . Map.toList` preserves the
+    -- invariants of order and non-duplication.
     ((accId, token), balance) : rest ->
         if balance > 0
         then Just ((accId, token, balance), Map.fromList rest)