From: Markus Triska <triska@metalevel.at>
Date: Sun, 8 Dec 2024 20:21:05 +0000 (+0100)
Subject: introduce and use weighted_maybe/2
X-Git-Tag: v0.10.0~95^2
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=abe1f37167b1f43637e64854d62410327c3e48c6;p=scryer-prolog.git

introduce and use weighted_maybe/2

Many thanks to @hurufu for the very nice definition!

This is until library(random) provides this functionality,
and a good name is found for it. See #2670.
---

diff --git a/src/lib/clpb.pl b/src/lib/clpb.pl
index a20694d0..7cf9e803 100644
--- a/src/lib/clpb.pl
+++ b/src/lib/clpb.pl
@@ -1550,11 +1550,15 @@ random_bindings(VNum, Node) -->
         { node_var_low_high(Node, Var, Low, High),
           bdd_count(Node, VNum, Total),
           bdd_count(Low, VNum, LCount) },
-        (   { maybe(LCount, Total) } ->
+        (   { weighted_maybe(LCount, Total) } ->
             [Var=0], random_bindings(VNum, Low)
         ;   [Var=1], random_bindings(VNum, High)
         ).
 
+weighted_maybe(K, N) :-
+        random_integer(0, N, X),
+        X < K.
+
 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Find solutions with maximum weight.
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */