Enhance error display

trans/transpiler/__init__.py

@@ -4,6 +4,7 @@ import builtins
 import inspect
 
 from transpiler.consts import MAPPINGS
+from transpiler.exceptions import CompileError
 from transpiler.phases.desugar_with import DesugarWith
 #from transpiler.phases import initial_pytype
 from transpiler.phases.emit_cpp.file import FileVisitor
@@ -51,9 +52,11 @@ def exception_hook(exc_type, exc_value, tb):
     if last_node is not None:
         print(f"In file \"{Fore.RESET}{last_file}{Fore.RED}\", line {last_node.lineno}")
         print("\t" + highlight(ast.unparse(last_node)))
-
+    print()
     print(f"{Fore.RED}Error:{Fore.RESET} {exc_value}")
+    if isinstance(exc_value, CompileError):
         print(inspect.cleandoc(exc_value.detail(last_node)))
+    print()
 
 sys.excepthook = exception_hook
 

trans/transpiler/phases/emit_cpp/module.py

@@ -46,7 +46,8 @@ class ModuleVisitor(BlockVisitor):
     def emit_python_func(self, mod: str, name: str, alias: str, fty: FunctionType) -> Iterable[str]:
         TB = f"emitting C++ code for Python function {highlight(f'{mod}.{name}')}"
 
-        yield f"auto {alias}("
+        yield "struct {"
+        yield f"auto operator()("
 
         for i, argty in enumerate(fty.parameters):
             if i != 0:
@@ -66,6 +67,7 @@ class ModuleVisitor(BlockVisitor):
         yield from self.visit(fty.return_type)
         yield ">();"
         yield "}"
+        yield f"}} {alias};"
 
     def visit_ImportFrom(self, node: ast.ImportFrom) -> Iterable[str]:
         if node.module_obj.is_python:
@@ -74,7 +76,6 @@ class ModuleVisitor(BlockVisitor):
                 assert isinstance(fty, FunctionType)
 
                 yield from self.emit_python_func(node.module, alias.name, alias.asname or alias.name, fty)
-            yield "// python"
         elif node.module in {"typon", "typing", "__future__"}:
             yield ""
         else:

trans/transpiler/phases/typing/exceptions.py

@@ -23,7 +23,7 @@ class UnresolvedTypeVariableError(CompileError):
             As such, you need to give enough information to the compiler to infer the type of the function.
             
             For example:
-                     vvv this tells the compiler that {highlight('math.factorial')} returns an {highlight('int')}
+                     ↓↓↓ this tells the compiler that {highlight('math.factorial')} returns an {highlight('int')}
                 {highlight('res: int = math.factorial(5)')}"""
         return """
         This generally indicates the compiler was unable to infer the type of a variable or expression.