added reset_seed

docs/scarpet/language/SystemFunctions.md

@@ -239,6 +239,11 @@ map(range(10), bool(rand(2))) => [false, false, true, false, false, false, true,
 map(range(10), str('%.1f',rand(_))) => [0.0, 0.4, 0.6, 1.9, 2.8, 3.8, 5.3, 2.2, 1.6, 5.6]
 </pre>
 
+## `reset_seed(seed)`
+
+Resets the sequence of the randomizer used by `rand` for this seed to its initial state. Returns a boolean value
+indicating if the given seed has been used or not.
+
 ### `perlin(x), perlin(x, y), perlin(x, y, z), perlin(x, y, z, seed)`
 
 returns a noise value from `0.0` to `1.0` (roughly) for 1, 2 or 3 dimensional coordinate. The default seed it samples 

docs/scarpet/resources/editors/idea/1.txt

@@ -63,6 +63,7 @@ reduce
 relu
 replace
 replace_first
+reset_seed
 return
 round
 sec

docs/scarpet/resources/editors/npp/scarpet.xml

@@ -25,7 +25,7 @@
             <Keywords name="Folders in comment, middle"></Keywords>
             <Keywords name="Folders in comment, close"></Keywords>
             <Keywords name="Keywords1">
-                not fact rand
+                not fact rand reset_seed
                 sin cos tan asin acos atan atan2 sinh cosh tanh sec csc sech csch cot acot coth asinh acosh atanh
                 rad deg
                 log log10 log1p
@@ -46,7 +46,7 @@
 
                 var undef vars if loop map filter first all c_for for while reduce continue break
 
-                import call outer type hash_code bool number str length rand sleep time profile_expr lower upper title replace replace_first
+                import call outer type hash_code bool number str length sleep time profile_expr lower upper title replace replace_first
             </Keywords>
             <Keywords name="Keywords2">
                 block pos pos_offset solid air liquid flammable

src/main/java/carpet/script/Expression.java

@@ -313,6 +313,11 @@ public class Expression
         addUnaryFunction(name, (v) -> new NumericValue(fun.apply(NumericValue.asNumber(v).getDouble())));
     }
 
+    public void addMathematicalUnaryIntFunction(String name, Function<Double, Long> fun)
+    {
+        addUnaryFunction(name, (v) -> new NumericValue(fun.apply(NumericValue.asNumber(v).getDouble())));
+    }
+
     public void addMathematicalBinaryFunction(String name, BiFunction<Double, Double, Double> fun)
     {
         addBinaryFunction(name, (w, v) ->

src/main/java/carpet/script/ScriptHost.java

@@ -42,6 +42,10 @@ public abstract class ScriptHost
         return randomizers.computeIfAbsent(aLong, Random::new);
     }
 
+    public boolean resetRandom(long aLong) {
+        return randomizers.remove(aLong) != null;
+    }
+
     public static class ModuleData
     {
         Module parent;

src/main/java/carpet/script/language/Sys.java

@@ -210,6 +210,10 @@ public class Sys {
             Value retval = new NumericValue(NumericValue.asNumber(argument).getDouble()*randomizer.nextDouble());
             return (cc, tt) -> retval;
         });
+        expression.addLazyFunction("reset_seed", 1, (c, t, lv) -> {
+            boolean gotIt = c.host.resetRandom(NumericValue.asNumber(lv.get(0).evalValue(c)).getLong());
+            return gotIt?LazyValue.TRUE:LazyValue.FALSE;
+        });
 
         expression.addLazyFunction("perlin", -1, (c, t, lv) ->
         {