Mal [c] … user () … Segmentation fault (core dumped) about mal HOT 6 CLOSED

Mal (like Clojure) has nil as a separate type/entity from the empty list.

Clojure treats () as the empty list, identical to '() or (quote ()). The last two work in Mal but simply () is treated as a function application and the function is not found (hence the exceptions/crashes).

Note that proper behaviour under bad input is not defined in Mal. For example, + requires two numeric arguments (e.g., (+ 10 26)), but it's undefined what will happen if you pass 0, 1 or 3 arguments to +, or pass string arguments, for example.

from mal.

@igravious an unquoted empty list is a common enough issue that implementations shouldn't crash. So we'll fix any implementations that crash. In the general case though, @dubek is correct. It's perfectly acceptable for individual mal implementations to do rigorous error checking and useful error reporting, however, requiring that of all implementations is a non-goal. I know it's a little bit unusual, but the goal of mal is to support learning of both Lisp and other languages. Each implementation should run correct mal code the same way, but completeness and productization of the implementation is up to the implementor of each implementation.

I'll keep this issue open to fix empty list unrecoverable crashes.

from mal.

I started fixing this in #194 . The travis status there will show how many more implementations need fixing.

from mal.

Super. I am still playing with Mal in a serious way. I appreciate the time you have taken to respond.

from mal.

This should be resolved now.

from mal.

Super. Mal has been a brilliant learning tool for me.

from mal.