Maintain random seed state in parser, not globally

packages/mini/krill-parser.js

@@ -279,7 +279,7 @@ function peg$parse(input, options) {
   var peg$f8 = function(p, s, r) { return x => x.options_['ops'].push({ type_: "bjorklund", arguments_ :{ pulse: p, step:s, rotation:r }}) };
   var peg$f9 = function(a) { return x => x.options_['ops'].push({ type_: "stretch", arguments_ :{ amount:a, type: 'slow' }}) };
   var peg$f10 = function(a) { return x => x.options_['ops'].push({ type_: "stretch", arguments_ :{ amount:a, type: 'fast' }}) };
-  var peg$f11 = function(a) { return x => x.options_['ops'].push({ type_: "degradeBy", arguments_ :{ amount:a } }) };
+  var peg$f11 = function(a) { return x => x.options_['ops'].push({ type_: "degradeBy", arguments_ :{ amount:a, seed: seed++ } }) };
   var peg$f12 = function(s) { return x => x.options_['ops'].push({ type_: "tail", arguments_ :{ element:s } }) };
   var peg$f13 = function(s, ops) { const result = new ElementStub(s, {ops: [], weight: 1, reps: 1});
     for (const op of ops) {
@@ -289,8 +289,8 @@ function peg$parse(input, options) {
   };
   var peg$f14 = function(s) { return new PatternStub(s, 'fastcat'); };
   var peg$f15 = function(tail) { return { alignment: 'stack', list: tail }; };
-  var peg$f16 = function(tail) { return { alignment: 'rand', list: tail }; };
+  var peg$f16 = function(tail) { return { alignment: 'rand', list: tail, seed: seed++ }; };
-  var peg$f17 = function(head, tail) { if (tail && tail.list.length > 0) { return new PatternStub([head, ...tail.list], tail.alignment); } else { return head; } };
+  var peg$f17 = function(head, tail) { if (tail && tail.list.length > 0) { return new PatternStub([head, ...tail.list], tail.alignment, tail.seed); } else { return head; } };
   var peg$f18 = function(head, tail) { return new PatternStub(tail ? [head, ...tail.list] : [head], 'polymeter'); };
   var peg$f19 = function(sc) { return sc; };
   var peg$f20 = function(s) { return { name: "struct", args: { mini:s }}};
@@ -2185,10 +2185,13 @@ function peg$parse(input, options) {
     this.location_ = location();
   }
 
-  var PatternStub = function(source, alignment)
+  var PatternStub = function(source, alignment, seed)
   {
     this.type_ = "pattern";
-    this.arguments_ = { alignment : alignment};
+    this.arguments_ = { alignment: alignment };
+    if (seed !== undefined) {
+      this.arguments_.seed = seed;
+    }
     this.source_ = source;
   }
 
@@ -2214,6 +2217,7 @@ function peg$parse(input, options) {
     this.options_ = options;
   }
 
+  var seed = 0;
 
   peg$result = peg$startRuleFunction();
 

packages/mini/krill.pegjs

@@ -19,10 +19,13 @@ This program is free software: you can redistribute it and/or modify it under th
     this.location_ = location();
   }
 
-  var PatternStub = function(source, alignment)
+  var PatternStub = function(source, alignment, seed)
   {
     this.type_ = "pattern";
-    this.arguments_ = { alignment : alignment};
+    this.arguments_ = { alignment: alignment };
+    if (seed !== undefined) {
+      this.arguments_.seed = seed;
+    }
     this.source_ = source;
   }
 
@@ -48,6 +51,7 @@ This program is free software: you can redistribute it and/or modify it under th
     this.options_ = options;
   }
 
+  var seed = 0;
 }
 
 start = statement
@@ -137,7 +141,7 @@ op_fast = "*"a:slice
   { return x => x.options_['ops'].push({ type_: "stretch", arguments_ :{ amount:a, type: 'fast' }}) }
 
 op_degrade = "?"a:number?
-  { return x => x.options_['ops'].push({ type_: "degradeBy", arguments_ :{ amount:a } }) }
+  { return x => x.options_['ops'].push({ type_: "degradeBy", arguments_ :{ amount:a, seed: seed++ } }) }
 
 op_tail = ":" s:slice
   { return x => x.options_['ops'].push({ type_: "tail", arguments_ :{ element:s } }) }
@@ -162,12 +166,12 @@ stack_tail = tail:(comma @sequence)+
 // a choose is a series of pipe-separated sequence, one of which is
 // chosen at random, each cycle
 choose_tail = tail:(pipe @sequence)+
-  { return { alignment: 'rand', list: tail }; }
+  { return { alignment: 'rand', list: tail, seed: seed++ }; }
 
 // if the stack contains only one element, we don't create a stack but return the
 // underlying element
 stack_or_choose = head:sequence tail:(stack_tail / choose_tail)?
-  { if (tail && tail.list.length > 0) { return new PatternStub([head, ...tail.list], tail.alignment); } else { return head; } }
+  { if (tail && tail.list.length > 0) { return new PatternStub([head, ...tail.list], tail.alignment, tail.seed); } else { return head; } }
 
 polymeter_stack = head:sequence tail:stack_tail?
   { return new PatternStub(tail ? [head, ...tail.list] : [head], 'polymeter'); }

packages/mini/mini.mjs

@@ -7,13 +7,8 @@ This program is free software: you can redistribute it and/or modify it under th
 import * as krill from './krill-parser.js';
 import * as strudel from '@strudel.cycles/core';
 
-/* var _seedState = 0;
 const randOffset = 0.0002;
 
-function _nextSeed() {
-  return _seedState++;
-} */
-
 const applyOptions = (parent, code) => (pat, i) => {
   const ast = parent.source_[i];
   const options = ast.options_;
@@ -44,27 +39,10 @@ const applyOptions = (parent, code) => (pat, i) => {
           break;
         }
         case 'degradeBy': {
-          // TODO: find out what is right here
+          pat = strudel.reify(pat)._degradeByWith(
-          // example:
+            strudel.rand.early(randOffset * op.arguments_.seed).segment(1),
-          /*
+            op.arguments_.amount ?? 0.5,
-           stack(
+          );
-             s("hh*8").degrade(),
-             s("[ht*8]?")
-           )
-        */
-          // above example will only be in sync when _degradeBy is used...
-          // it also seems that the nextSeed will create undeterministic behaviour
-          // as it uses a global _seedState. This is probably the reason for
-          // https://github.com/tidalcycles/strudel/issues/245
-
-          // this is how it was:
-          /* 
-        return strudel.reify(pat)._degradeByWith(
-          strudel.rand.early(randOffset * _nextSeed()).segment(1),
-          op.arguments_.amount ?? 0.5,
-        ); 
-        */
-          pat = strudel.reify(pat).degradeBy(op.arguments_.amount === null ? 0.5 : op.arguments_.amount);
           break;
         }
         case 'tail': {
@@ -114,9 +92,7 @@ export function patternifyAST(ast, code) {
         return strudel.stack(...aligned);
       }
       if (alignment === 'rand') {
-        // https://github.com/tidalcycles/strudel/issues/245#issuecomment-1345406422
+        return strudel.chooseInWith(strudel.rand.early(randOffset * ast.arguments_.seed).segment(1), children);
-        // return strudel.chooseInWith(strudel.rand.early(randOffset * _nextSeed()).segment(1), children);
-        return strudel.chooseCycles(...children);
       }
       const weightedChildren = ast.source_.some((child) => !!child.options_?.weight);
       if (!weightedChildren && alignment === 'slowcat') {

test/__snapshots__/tunes.test.mjs.snap

@@ -63,6 +63,7 @@ exports[`renders tunes > tune: arpoon 1`] = `
   "[ 0/1 → 1/2 | s:bd bank:RolandTR909 gain:0.5 ]",
   "[ 1/2 → 1/1 | s:bd bank:RolandTR909 gain:0.5 ]",
   "[ 1/2 → 2/3 | s:hh bank:RolandTR909 gain:0.5 ]",
+  "[ 5/6 → 1/1 | s:hh bank:RolandTR909 gain:0.5 ]",
 ]
 `;