Why does this give a choicepoint?

General
21

@brebs Hmm, you’re well past my current level of Prolog with that code! I’ve seen the (... -> ... ; ... ) construct around, but have no idea what it means yet.

Is there a simple explanation, or do I note it down with the other million Prolog features I want to learn :smiley:

Thanks as ever

22

It’s just if… then… else

Link to docs: ->/2

23

Thanks, another thing to add to my list of bed-time reading!

24

For a bit of historical trivia about the way SWI-Prolog treats the empty list (or more
properly the list terminator constant) see 5.1 Lists are special.

2 Likes
25

Thanks for that, interesting background!