Add tests

integration_tests/CMakeLists.txt

@@ -525,6 +525,8 @@ RUN(NAME global_syms_04    LABELS cpython llvm c wasm wasm_x64)
 RUN(NAME global_syms_05    LABELS cpython llvm c)
 RUN(NAME global_syms_06    LABELS cpython llvm c)
 
+RUN(NAME callback_01       LABELS cpython llvm)
+
 # Intrinsic Functions
 RUN(NAME intrinsics_01     LABELS cpython llvm) # any
 

integration_tests/callback_01.py

@@ -0,0 +1,26 @@
+from lpython import i32, Callable
+
+
+def f(x: i32) -> i32:
+    return x + 1
+
+def f2(x: i32) -> i32:
+    return x + 10
+
+def f3(x: i32) -> i32:
+    return f(x) + f2(x)
+
+
+def g(func: Callable[[i32], i32], arg: i32) -> i32:
+    ret: i32
+    ret = func(arg)
+    return ret
+
+
+def check():
+    assert g(f, 10) == 11
+    assert g(f2, 20) == 30
+    assert g(f3, 5) == 21
+
+
+check()

src/runtime/lpython/lpython.py

@@ -9,7 +9,7 @@
 __slots__ = ["i8", "i16", "i32", "i64", "f32", "f64", "c32", "c64", "CPtr",
         "overload", "ccall", "TypeVar", "pointer", "c_p_pointer", "Pointer",
         "p_c_pointer", "vectorize", "inline", "Union", "static", "with_goto",
-        "packed", "Const", "sizeof", "ccallable", "ccallback"]
+        "packed", "Const", "sizeof", "ccallable", "ccallback", "Callable"]
 
 # data-types
 
@@ -55,6 +55,7 @@ def __init__(self, type, dims):
 c64 = Type("c64")
 CPtr = Type("c_ptr")
 Const = ConstType("Const")
+Callable = Type("Callable")
 Union = ctypes.Union
 Pointer = PointerType("Pointer")