Add Callable type

integration_tests/CMakeLists.txt

@@ -724,6 +724,10 @@ RUN(NAME callback_01       LABELS cpython llvm c)
 RUN(NAME callback_02       LABELS cpython llvm c)
 RUN(NAME callback_03       LABELS cpython llvm c)
 
+
+# callback_04 is to test emulation. So just run with cpython
+RUN(NAME callback_04       IMPORT_PATH .. LABELS cpython)
+
 # Intrinsic Functions
 RUN(NAME intrinsics_01     LABELS cpython llvm NOFAST) # any
 

integration_tests/callback_04.py

@@ -0,0 +1,18 @@
+import lpython
+from lpython import i32
+from types import FunctionType
+import callback_04_module
+
+lpython.CTypes.emulations = {k: v for k, v in callback_04_module.__dict__.items()
+        if isinstance(v, FunctionType)}
+
+
+def foo(x : i32) -> i32:
+    assert x == 3
+    print(x)
+    return x
+
+def entry_point() -> None:
+    callback_04_module.bar(foo, 3)
+
+entry_point()

integration_tests/callback_04_module.py

@@ -0,0 +1,4 @@
+from lpython import i32, Callable
+
+def bar(func : Callable[[i32], i32], arg : i32) -> i32:
+    return func(arg)

src/runtime/lpython/lpython.py

@@ -287,6 +287,8 @@ def convert_type_to_ctype(arg):
         return c_double_complex
     elif arg == bool:
         return ctypes.c_bool
+    elif arg == Callable:
+        return ctypes.PYFUNCTYPE(None)
     elif arg is None:
         raise NotImplementedError("Type cannot be None")
     elif isinstance(arg, Array):