Comment by danieldk

I'm currently using SWI-Prolog.

Still checking every now and then if SICStus has open sourced. I used Prolog daily during my PhD and SICStus had such nice features. E.g. it could raise an exception when no more heap space can be allocated or when a 'call' would not finish within a given time. These features made it much easier to use Prolog in real-world systems (this was a parsing system and when parsing a very large corpus, this was highly preferable over simply crashing the interpreter).

Maybe things have changed, but this wasn't possible with SWI at the time. Even worse, most C extensions would use malloc directly, making it impossible to track allocations done by extensions.