fix!: Make list length op give back the list (#1547)

Fixes #1543. BREAKING CHANGE: The `length` op in the std `collections` extensions now also returns the list.
CQCL · Oct 3, 2024 · cf31698 · cf31698
1 parent ea8e818
commit cf31698
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diff --git a/hugr-core/src/std_extensions/collections.rs b/hugr-core/src/std_extensions/collections.rs
@@ -178,7 +178,7 @@ impl ListOp {
                     vec![l, either_type(e, Type::UNIT).into()],
                 )
                 .into(),
-            length => self.list_polytype(vec![l], vec![USIZE_T]).into(),
+            length => self.list_polytype(vec![l.clone()], vec![l, USIZE_T]).into(),
         }
     }
 

diff --git a/hugr-py/src/hugr/std/_json_defs/collections.json b/hugr-py/src/hugr/std/_json_defs/collections.json
@@ -189,6 +189,22 @@
             }
           ],
           "output": [
+            {
+              "t": "Opaque",
+              "extension": "collections",
+              "id": "List",
+              "args": [
+                {
+                  "tya": "Type",
+                  "ty": {
+                    "t": "V",
+                    "i": 0,
+                    "b": "A"
+                  }
+                }
+              ],
+              "bound": "A"
+            },
             {
               "t": "I"
             }

diff --git a/specification/std_extensions/collections.json b/specification/std_extensions/collections.json
@@ -189,6 +189,22 @@
             }
           ],
           "output": [
+            {
+              "t": "Opaque",
+              "extension": "collections",
+              "id": "List",
+              "args": [
+                {
+                  "tya": "Type",
+                  "ty": {
+                    "t": "V",
+                    "i": 0,
+                    "b": "A"
+                  }
+                }
+              ],
+              "bound": "A"
+            },
             {
               "t": "I"
             }