feat(py): add ArrayVal

hugr-py/src/hugr/std/collections/array.py

@@ -4,8 +4,9 @@
 
 from dataclasses import dataclass
 
-import hugr.tys as tys
+from hugr import tys, val
 from hugr.std import _load_extension
+from hugr.utils import comma_sep_str
 
 EXTENSION = _load_extension("collections.array")
 
@@ -14,7 +15,7 @@
 class Array(tys.ExtType):
     """Fixed `size` array of `ty` elements."""
 
-    def __init__(self, ty: tys.Type, size: int | tys.BoundedNatArg) -> None:
+    def __init__(self, ty: tys.Type, size: int | tys.TypeArg) -> None:
         if isinstance(size, int):
             size = tys.BoundedNatArg(size)
 
@@ -52,3 +53,25 @@ def size(self) -> int | None:
 
     def type_bound(self) -> tys.TypeBound:
         return self.ty.type_bound()
+
+
+@dataclass
+class ArrayVal(val.ExtensionValue):
+    """Constant value for a statically sized array of elements."""
+
+    v: list[val.Value]
+    ty: tys.Type
+
+    def __init__(self, v: list[val.Value], elem_ty: tys.Type) -> None:
+        self.v = v
+        self.ty = Array(elem_ty, len(v))
+
+    def to_value(self) -> val.Extension:
+        name = "ArrayValue"
+        # The value list must be serialized at this point, otherwise the
+        # `Extension` value would not be serializable.
+        vs = [v._to_serial_root() for v in self.v]
+        return val.Extension(name, typ=self.ty, val=vs, extensions=[EXTENSION.name])
+
+    def __str__(self) -> str:
+        return f"array({comma_sep_str(self.v)})"

hugr-py/tests/test_tys.py

@@ -3,7 +3,7 @@
 import pytest
 
 from hugr import val
-from hugr.std.collections.array import Array
+from hugr.std.collections.array import Array, ArrayVal
 from hugr.std.collections.list import List, ListVal
 from hugr.std.float import FLOAT_T
 from hugr.std.int import INT_T, _int_tv
@@ -170,3 +170,7 @@ def test_array():
     ls = Array(ty_var, len_var)
     assert ls.ty == ty_var
     assert ls.size is None
+
+    ar_val = ArrayVal([val.TRUE, val.FALSE], Bool)
+    assert ar_val.v == [val.TRUE, val.FALSE]
+    assert ar_val.ty == Array(Bool, 2)