#define lambda(ret_type, _body) ({ ret_type _ _body _; }) I found this one really fascinating, they're using both statement expression and nested functions. T

#define lambda(ret_type, _body) ({ ret_type _ _body _; }) I found this one really fascinating, they're using both statement expression and nested functions. Their (reformatted) example of: int (*max)(int, int) = lambda(int, (int x, int y) { return x > y ? x : y; }); macro-expands to int (*max)(int, int) = ({ int _(int x, int y) { return x > y ? x : y;}; }); So they have a statement-expression with just one statement in it - the value of that statement is the value of the whole statement-expression. And the one statement inside the statement expression is a declaration of a nested function named _. Statement-expressions decay their return types, so that function gets converted to a function pointer. And thus your "lambda" is a pointer to a GCC nested function.