feat: Add string type (#733)

Closes #695

(Pending hugr release including commit b05a419)

guppylang/checker/core.py

@@ -30,6 +30,7 @@
     nat_type_def,
     none_type_def,
     sized_iter_type_def,
+    string_type_def,
     tuple_type_def,
 )
 from guppylang.tys.param import Parameter
@@ -237,6 +238,7 @@ def default() -> "Globals":
             nat_type_def,
             int_type_def,
             float_type_def,
+            string_type_def,
             list_type_def,
             array_type_def,
             sized_iter_type_def,

guppylang/checker/expr_checker.py

@@ -117,6 +117,7 @@
     is_sized_iter_type,
     list_type,
     nat_type,
+    string_type,
 )
 from guppylang.tys.param import ConstParam, TypeParam
 from guppylang.tys.subst import Inst, Subst
@@ -1179,6 +1180,8 @@ def python_value_to_guppy_type(
     match v:
         case bool():
             return bool_type()
+        case str():
+            return string_type()
         # Only resolve `int` to `nat` if the user specifically asked for it
         case int(n) if type_hint == nat_type() and n >= 0:
             return nat_type()

guppylang/compiler/expr_compiler.py

@@ -9,6 +9,7 @@
 import hugr.std.float
 import hugr.std.int
 import hugr.std.logic
+import hugr.std.prelude
 from hugr import Hugr, Wire, ops
 from hugr import tys as ht
 from hugr import val as hv
@@ -596,6 +597,8 @@ def python_value_to_hugr(v: Any, exp_ty: Type) -> hv.Value | None:
     match v:
         case bool():
             return hv.bool_value(v)
+        case str():
+            return hugr.std.prelude.StringVal(v)
         case int():
             return hugr.std.int.IntVal(v, width=NumericType.INT_WIDTH)
         case float():

guppylang/std/builtins.py

@@ -46,6 +46,7 @@
     list_type_def,
     nat_type_def,
     sized_iter_type_def,
+    string_type_def,
 )
 
 guppy.init_module(import_builtins=False)
@@ -121,6 +122,12 @@ def __or__(self: bool, other: bool) -> bool: ...
     def __xor__(self: bool, other: bool) -> bool: ...
 
 
+@guppy.extend_type(string_type_def)
+class String:
+    @guppy.custom(checker=UnsupportedChecker(), higher_order_value=False)
+    def __new__(x): ...
+
+
 @guppy.extend_type(nat_type_def)
 class Nat:
     @guppy.custom(NoopCompiler())
@@ -890,10 +897,6 @@ def sorted(x): ...
 def staticmethod(x): ...
 
 
-@guppy.custom(checker=UnsupportedChecker(), higher_order_value=False)
-def str(x): ...
-
-
 @guppy.custom(checker=UnsupportedChecker(), higher_order_value=False)
 def sum(x): ...
 

guppylang/tys/builtin.py

@@ -168,6 +168,14 @@ def _sized_iter_to_hugr(args: Sequence[Argument]) -> ht.Type:
 float_type_def = _NumericTypeDef(
     DefId.fresh(), "float", None, NumericType(NumericType.Kind.Float)
 )
+string_type_def = OpaqueTypeDef(
+    id=DefId.fresh(),
+    name="str",
+    defined_at=None,
+    params=[],
+    always_linear=False,
+    to_hugr=lambda _: hugr.std.PRELUDE.get_type("string").instantiate([]),
+)
 list_type_def = _ListTypeDef(
     id=DefId.fresh(),
     name="list",
@@ -216,6 +224,10 @@ def float_type() -> NumericType:
     return NumericType(NumericType.Kind.Float)
 
 
+def string_type() -> OpaqueType:
+    return OpaqueType([], string_type_def)
+
+
 def list_type(element_ty: Type) -> OpaqueType:
     return OpaqueType([TypeArg(element_ty)], list_type_def)
 
@@ -236,6 +248,10 @@ def is_bool_type(ty: Type) -> bool:
     return isinstance(ty, OpaqueType) and ty.defn == bool_type_def
 
 
+def is_string_type(ty: Type) -> bool:
+    return isinstance(ty, OpaqueType) and ty.defn == string_type_def
+
+
 def is_list_type(ty: Type) -> bool:
     return isinstance(ty, OpaqueType) and ty.defn == list_type_def
 

tests/error/misc_errors/unsupported_const.err

@@ -1,8 +1,8 @@
-Error: Unsupported constant (at $FILE:7:8)
+Error: Unsupported constant (at $FILE:6:9)
   | 
-5 | @compile_guppy
-6 | def foo() -> None:
-7 |     x = "foo"
-  |         ^^^^^ Type `str` is not supported
+4 | @compile_guppy
+5 | def foo() -> None:
+6 |     x = -2j
+  |          ^^ Type `complex` is not supported
 
 Guppy compilation failed due to 1 previous error

tests/error/misc_errors/unsupported_const.py

@@ -1,7 +1,6 @@
-from guppylang.std.builtins import array
 from tests.util import compile_guppy
 
 
 @compile_guppy
 def foo() -> None:
-    x = "foo"
+    x = -2j

tests/integration/test_py.py

@@ -117,6 +117,14 @@ def foo() -> None:
     validate(foo)
 
 
+def test_strings(validate):
+    @compile_guppy
+    def foo() -> None:
+        x: str = py("a" + "b")
+
+    validate(foo)
+
+
 @pytest.mark.skipif(not tket2_installed, reason="Tket2 is not installed")
 @pytest.mark.skip("Fails because of extensions in types #343")
 def test_pytket_single_qubit(validate):

tests/integration/test_strings.py

@@ -0,0 +1,35 @@
+from guppylang.decorator import guppy
+from guppylang.module import GuppyModule
+from tests.util import compile_guppy
+
+import pytest
+
+def test_basic_type(validate):
+    @compile_guppy
+    def foo(x: str) -> str:
+        return x
+
+    validate(foo)
+
+
+def test_basic_value(validate):
+    @compile_guppy
+    def foo() -> str:
+        x = "Hello World"
+        return x
+
+    validate(foo)
+
+
+def test_struct(validate):
+    module = GuppyModule("module")
+
+    @guppy.struct(module)
+    class StringStruct:
+        x: str
+
+    @guppy(module)
+    def main(s: StringStruct) -> None:
+        StringStruct("Lorem Ipsum")
+
+    validate(module.compile())