Special case parsing of Callable

tests/error/misc_errors/callable_no_args.err

@@ -0,0 +1,6 @@
+Guppy compilation failed. Error in file $FILE:10
+
+8:     @guppy.declare(module)
+9:     def foo(f: Callable) -> None: ...
+                  ^^^^^^^^
+GuppyError: Function types should be specified via `Callable[[<arguments>], <return types>]`

tests/error/misc_errors/callable_no_args.py

@@ -0,0 +1,13 @@
+from typing import Callable
+
+from guppylang.decorator import guppy
+from guppylang.module import GuppyModule
+
+
+module = GuppyModule("test")
+
+@guppy.declare(module)
+def foo(f: "Callable[None]") -> None: ...
+
+
+module.compile()

tests/error/misc_errors/callable_not_list1.err

@@ -0,0 +1,6 @@
+Guppy compilation failed. Error in file $FILE:10
+
+8:     @guppy.declare(module)
+9:     def foo(f: "Callable[int, float, bool]") -> None: ...
+                   ^^^^^^^^^^^^^^^^^^^^^^^^^^
+GuppyError: Function types should be specified via `Callable[[<arguments>], <return types>]`

tests/error/misc_errors/callable_not_list1.py

@@ -0,0 +1,13 @@
+from typing import Callable
+
+from guppylang.decorator import guppy
+from guppylang.module import GuppyModule
+
+
+module = GuppyModule("test")
+
+@guppy.declare(module)
+def foo(f: "Callable[int, float, bool]") -> None: ...
+
+
+module.compile()

tests/error/misc_errors/callable_not_list2.err

@@ -0,0 +1,6 @@
+Guppy compilation failed. Error in file $FILE:10
+
+8:     @guppy.declare(module)
+9:     def foo(f: "Callable[None]") -> None: ...
+                   ^^^^^^^^^^^^^^
+GuppyError: Function types should be specified via `Callable[[<arguments>], <return types>]`

tests/error/misc_errors/callable_not_list2.py

@@ -0,0 +1,13 @@
+from typing import Callable
+
+from guppylang.decorator import guppy
+from guppylang.module import GuppyModule
+
+
+module = GuppyModule("test")
+
+@guppy.declare(module)
+def foo(f: "Callable[int, float, bool]") -> None: ...
+
+
+module.compile()