diff --git a/repl/krill-parser.js b/repl/krill-parser.js
new file mode 100644
index 00000000..db17b13f
--- /dev/null
+++ b/repl/krill-parser.js
@@ -0,0 +1,1916 @@
+// Generated by Peggy 1.2.0.
+//
+// https://peggyjs.org/
+
+function peg$subclass(child, parent) {
+  function C() { this.constructor = child; }
+  C.prototype = parent.prototype;
+  child.prototype = new C();
+}
+
+function peg$SyntaxError(message, expected, found, location) {
+  var self = Error.call(this, message);
+  if (Object.setPrototypeOf) {
+    Object.setPrototypeOf(self, peg$SyntaxError.prototype);
+  }
+  self.expected = expected;
+  self.found = found;
+  self.location = location;
+  self.name = "SyntaxError";
+  return self;
+}
+
+peg$subclass(peg$SyntaxError, Error);
+
+function peg$padEnd(str, targetLength, padString) {
+  padString = padString || " ";
+  if (str.length > targetLength) { return str; }
+  targetLength -= str.length;
+  padString += padString.repeat(targetLength);
+  return str + padString.slice(0, targetLength);
+}
+
+peg$SyntaxError.prototype.format = function(sources) {
+  var str = "Error: " + this.message;
+  if (this.location) {
+    var src = null;
+    var k;
+    for (k = 0; k < sources.length; k++) {
+      if (sources[k].source === this.location.source) {
+        src = sources[k].text.split(/\r\n|\n|\r/g);
+        break;
+      }
+    }
+    var s = this.location.start;
+    var loc = this.location.source + ":" + s.line + ":" + s.column;
+    if (src) {
+      var e = this.location.end;
+      var filler = peg$padEnd("", s.line.toString().length);
+      var line = src[s.line - 1];
+      var last = s.line === e.line ? e.column : line.length + 1;
+      str += "\n --> " + loc + "\n"
+          + filler + " |\n"
+          + s.line + " | " + line + "\n"
+          + filler + " | " + peg$padEnd("", s.column - 1)
+          + peg$padEnd("", last - s.column, "^");
+    } else {
+      str += "\n at " + loc;
+    }
+  }
+  return str;
+};
+
+peg$SyntaxError.buildMessage = function(expected, found) {
+  var DESCRIBE_EXPECTATION_FNS = {
+    literal: function(expectation) {
+      return "\"" + literalEscape(expectation.text) + "\"";
+    },
+
+    class: function(expectation) {
+      var escapedParts = expectation.parts.map(function(part) {
+        return Array.isArray(part)
+          ? classEscape(part[0]) + "-" + classEscape(part[1])
+          : classEscape(part);
+      });
+
+      return "[" + (expectation.inverted ? "^" : "") + escapedParts + "]";
+    },
+
+    any: function() {
+      return "any character";
+    },
+
+    end: function() {
+      return "end of input";
+    },
+
+    other: function(expectation) {
+      return expectation.description;
+    }
+  };
+
+  function hex(ch) {
+    return ch.charCodeAt(0).toString(16).toUpperCase();
+  }
+
+  function literalEscape(s) {
+    return s
+      .replace(/\\/g, "\\\\")
+      .replace(/"/g,  "\\\"")
+      .replace(/\0/g, "\\0")
+      .replace(/\t/g, "\\t")
+      .replace(/\n/g, "\\n")
+      .replace(/\r/g, "\\r")
+      .replace(/[\x00-\x0F]/g,          function(ch) { return "\\x0" + hex(ch); })
+      .replace(/[\x10-\x1F\x7F-\x9F]/g, function(ch) { return "\\x"  + hex(ch); });
+  }
+
+  function classEscape(s) {
+    return s
+      .replace(/\\/g, "\\\\")
+      .replace(/\]/g, "\\]")
+      .replace(/\^/g, "\\^")
+      .replace(/-/g,  "\\-")
+      .replace(/\0/g, "\\0")
+      .replace(/\t/g, "\\t")
+      .replace(/\n/g, "\\n")
+      .replace(/\r/g, "\\r")
+      .replace(/[\x00-\x0F]/g,          function(ch) { return "\\x0" + hex(ch); })
+      .replace(/[\x10-\x1F\x7F-\x9F]/g, function(ch) { return "\\x"  + hex(ch); });
+  }
+
+  function describeExpectation(expectation) {
+    return DESCRIBE_EXPECTATION_FNS[expectation.type](expectation);
+  }
+
+  function describeExpected(expected) {
+    var descriptions = expected.map(describeExpectation);
+    var i, j;
+
+    descriptions.sort();
+
+    if (descriptions.length > 0) {
+      for (i = 1, j = 1; i < descriptions.length; i++) {
+        if (descriptions[i - 1] !== descriptions[i]) {
+          descriptions[j] = descriptions[i];
+          j++;
+        }
+      }
+      descriptions.length = j;
+    }
+
+    switch (descriptions.length) {
+      case 1:
+        return descriptions[0];
+
+      case 2:
+        return descriptions[0] + " or " + descriptions[1];
+
+      default:
+        return descriptions.slice(0, -1).join(", ")
+          + ", or "
+          + descriptions[descriptions.length - 1];
+    }
+  }
+
+  function describeFound(found) {
+    return found ? "\"" + literalEscape(found) + "\"" : "end of input";
+  }
+
+  return "Expected " + describeExpected(expected) + " but " + describeFound(found) + " found.";
+};
+
+function peg$parse(input, options) {
+  options = options !== undefined ? options : {};
+
+  var peg$FAILED = {};
+  var peg$source = options.grammarSource;
+
+  var peg$startRuleFunctions = { start: peg$parsestart };
+  var peg$startRuleFunction = peg$parsestart;
+
+  var peg$c0 = ".";
+  var peg$c1 = "-";
+  var peg$c2 = "+";
+  var peg$c3 = "0";
+  var peg$c4 = ",";
+  var peg$c5 = "\"";
+  var peg$c6 = "'";
+  var peg$c7 = "#";
+  var peg$c8 = "[";
+  var peg$c9 = "]";
+  var peg$c10 = "<";
+  var peg$c11 = ">";
+  var peg$c12 = "@";
+  var peg$c13 = "(";
+  var peg$c14 = ")";
+  var peg$c15 = "/";
+  var peg$c16 = "*";
+  var peg$c17 = "%";
+  var peg$c18 = "struct";
+  var peg$c19 = "target";
+  var peg$c20 = "euclid";
+  var peg$c21 = "slow";
+  var peg$c22 = "rotL";
+  var peg$c23 = "rotR";
+  var peg$c24 = "fast";
+  var peg$c25 = "scale";
+  var peg$c26 = "//";
+  var peg$c27 = "cat";
+  var peg$c28 = "$";
+  var peg$c29 = "setcps";
+  var peg$c30 = "setbpm";
+  var peg$c31 = "hush";
+
+  var peg$r0 = /^[1-9]/;
+  var peg$r1 = /^[eE]/;
+  var peg$r2 = /^[0-9]/;
+  var peg$r3 = /^[ \n\r\t]/;
+  var peg$r4 = /^[0-9a-zA-Z~]/;
+  var peg$r5 = /^[^\n]/;
+
+  var peg$e0 = peg$otherExpectation("number");
+  var peg$e1 = peg$literalExpectation(".", false);
+  var peg$e2 = peg$classExpectation([["1", "9"]], false, false);
+  var peg$e3 = peg$classExpectation(["e", "E"], false, false);
+  var peg$e4 = peg$literalExpectation("-", false);
+  var peg$e5 = peg$literalExpectation("+", false);
+  var peg$e6 = peg$literalExpectation("0", false);
+  var peg$e7 = peg$classExpectation([["0", "9"]], false, false);
+  var peg$e8 = peg$otherExpectation("whitespace");
+  var peg$e9 = peg$classExpectation([" ", "\n", "\r", "\t"], false, false);
+  var peg$e10 = peg$literalExpectation(",", false);
+  var peg$e11 = peg$literalExpectation("\"", false);
+  var peg$e12 = peg$literalExpectation("'", false);
+  var peg$e13 = peg$classExpectation([["0", "9"], ["a", "z"], ["A", "Z"], "~"], false, false);
+  var peg$e14 = peg$literalExpectation("#", false);
+  var peg$e15 = peg$literalExpectation("[", false);
+  var peg$e16 = peg$literalExpectation("]", false);
+  var peg$e17 = peg$literalExpectation("<", false);
+  var peg$e18 = peg$literalExpectation(">", false);
+  var peg$e19 = peg$literalExpectation("@", false);
+  var peg$e20 = peg$literalExpectation("(", false);
+  var peg$e21 = peg$literalExpectation(")", false);
+  var peg$e22 = peg$literalExpectation("/", false);
+  var peg$e23 = peg$literalExpectation("*", false);
+  var peg$e24 = peg$literalExpectation("%", false);
+  var peg$e25 = peg$literalExpectation("struct", false);
+  var peg$e26 = peg$literalExpectation("target", false);
+  var peg$e27 = peg$literalExpectation("euclid", false);
+  var peg$e28 = peg$literalExpectation("slow", false);
+  var peg$e29 = peg$literalExpectation("rotL", false);
+  var peg$e30 = peg$literalExpectation("rotR", false);
+  var peg$e31 = peg$literalExpectation("fast", false);
+  var peg$e32 = peg$literalExpectation("scale", false);
+  var peg$e33 = peg$literalExpectation("//", false);
+  var peg$e34 = peg$classExpectation(["\n"], true, false);
+  var peg$e35 = peg$literalExpectation("cat", false);
+  var peg$e36 = peg$literalExpectation("$", false);
+  var peg$e37 = peg$literalExpectation("setcps", false);
+  var peg$e38 = peg$literalExpectation("setbpm", false);
+  var peg$e39 = peg$literalExpectation("hush", false);
+
+  var peg$f0 = function() { return parseFloat(text()); };
+  var peg$f1 = function(chars) { return chars.join("") };
+  var peg$f2 = function(s) { return s};
+  var peg$f3 = function(sc) { sc.arguments_.alignment = "t"; return sc;};
+  var peg$f4 = function(a) { return { weight: a} };
+  var peg$f5 = function(p, s) { return { operator : { type_: "bjorklund", arguments_ :{ pulse: p, step:s } } } };
+  var peg$f6 = function(a) { return { operator : { type_: "stretch", arguments_ :{ amount:a } } } };
+  var peg$f7 = function(a) { return { operator : { type_: "stretch", arguments_ :{ amount:"1/"+a } } } };
+  var peg$f8 = function(a) { return { operator : { type_: "fixed-step", arguments_ :{ amount:a } } } };
+  var peg$f9 = function(s, o) { return new ElementStub(s, o);};
+  var peg$f10 = function(s) { return new PatternStub(s,"h"); };
+  var peg$f11 = function(c, v) { return v};
+  var peg$f12 = function(c, cs) { if (cs.length == 0 && c instanceof Object) { return c;} else { cs.unshift(c); return new PatternStub(cs,"v");}  };
+  var peg$f13 = function(s) { return s; };
+  var peg$f14 = function(s) { return { name: "struct", args: { sequence:s }}};
+  var peg$f15 = function(s) { return { name: "target", args : { name:s}}};
+  var peg$f16 = function(p, s) { return { name: "bjorklund", args :{ pulse: parseInt(p), step:parseInt(s) }}};
+  var peg$f17 = function(a) { return { name: "stretch", args :{ amount: a}}};
+  var peg$f18 = function(a) { return { name: "shift", args :{ amount: "-"+a}}};
+  var peg$f19 = function(a) { return { name: "shift", args :{ amount: a}}};
+  var peg$f20 = function(a) { return { name: "stretch", args :{ amount: "1/"+a}}};
+  var peg$f21 = function(s) { return { name: "scale", args :{ scale: s.join("")}}};
+  var peg$f22 = function(s, v) { return v};
+  var peg$f23 = function(s, ss) { ss.unshift(s); return new PatternStub(ss,"t"); };
+  var peg$f24 = function(sg) {return sg};
+  var peg$f25 = function(o, soc) { return new OperatorStub(o.name,o.args,soc)};
+  var peg$f26 = function(sc) { return sc };
+  var peg$f27 = function(c) { return c };
+  var peg$f28 = function(v) { return new CommandStub("setcps", { value: v})};
+  var peg$f29 = function(v) { return new CommandStub("setcps", { value: (v/120/2)})};
+  var peg$f30 = function() { return new CommandStub("hush")};
+
+  var peg$currPos = 0;
+  var peg$savedPos = 0;
+  var peg$posDetailsCache = [{ line: 1, column: 1 }];
+  var peg$maxFailPos = 0;
+  var peg$maxFailExpected = [];
+  var peg$silentFails = 0;
+
+  var peg$result;
+
+  if ("startRule" in options) {
+    if (!(options.startRule in peg$startRuleFunctions)) {
+      throw new Error("Can't start parsing from rule \"" + options.startRule + "\".");
+    }
+
+    peg$startRuleFunction = peg$startRuleFunctions[options.startRule];
+  }
+
+  function text() {
+    return input.substring(peg$savedPos, peg$currPos);
+  }
+
+  function offset() {
+    return peg$savedPos;
+  }
+
+  function range() {
+    return {
+      source: peg$source,
+      start: peg$savedPos,
+      end: peg$currPos
+    };
+  }
+
+  function location() {
+    return peg$computeLocation(peg$savedPos, peg$currPos);
+  }
+
+  function expected(description, location) {
+    location = location !== undefined
+      ? location
+      : peg$computeLocation(peg$savedPos, peg$currPos);
+
+    throw peg$buildStructuredError(
+      [peg$otherExpectation(description)],
+      input.substring(peg$savedPos, peg$currPos),
+      location
+    );
+  }
+
+  function error(message, location) {
+    location = location !== undefined
+      ? location
+      : peg$computeLocation(peg$savedPos, peg$currPos);
+
+    throw peg$buildSimpleError(message, location);
+  }
+
+  function peg$literalExpectation(text, ignoreCase) {
+    return { type: "literal", text: text, ignoreCase: ignoreCase };
+  }
+
+  function peg$classExpectation(parts, inverted, ignoreCase) {
+    return { type: "class", parts: parts, inverted: inverted, ignoreCase: ignoreCase };
+  }
+
+  function peg$anyExpectation() {
+    return { type: "any" };
+  }
+
+  function peg$endExpectation() {
+    return { type: "end" };
+  }
+
+  function peg$otherExpectation(description) {
+    return { type: "other", description: description };
+  }
+
+  function peg$computePosDetails(pos) {
+    var details = peg$posDetailsCache[pos];
+    var p;
+
+    if (details) {
+      return details;
+    } else {
+      p = pos - 1;
+      while (!peg$posDetailsCache[p]) {
+        p--;
+      }
+
+      details = peg$posDetailsCache[p];
+      details = {
+        line: details.line,
+        column: details.column
+      };
+
+      while (p < pos) {
+        if (input.charCodeAt(p) === 10) {
+          details.line++;
+          details.column = 1;
+        } else {
+          details.column++;
+        }
+
+        p++;
+      }
+
+      peg$posDetailsCache[pos] = details;
+
+      return details;
+    }
+  }
+
+  function peg$computeLocation(startPos, endPos) {
+    var startPosDetails = peg$computePosDetails(startPos);
+    var endPosDetails = peg$computePosDetails(endPos);
+
+    return {
+      source: peg$source,
+      start: {
+        offset: startPos,
+        line: startPosDetails.line,
+        column: startPosDetails.column
+      },
+      end: {
+        offset: endPos,
+        line: endPosDetails.line,
+        column: endPosDetails.column
+      }
+    };
+  }
+
+  function peg$fail(expected) {
+    if (peg$currPos < peg$maxFailPos) { return; }
+
+    if (peg$currPos > peg$maxFailPos) {
+      peg$maxFailPos = peg$currPos;
+      peg$maxFailExpected = [];
+    }
+
+    peg$maxFailExpected.push(expected);
+  }
+
+  function peg$buildSimpleError(message, location) {
+    return new peg$SyntaxError(message, null, null, location);
+  }
+
+  function peg$buildStructuredError(expected, found, location) {
+    return new peg$SyntaxError(
+      peg$SyntaxError.buildMessage(expected, found),
+      expected,
+      found,
+      location
+    );
+  }
+
+  function peg$parsestart() {
+    var s0;
+
+    s0 = peg$parsestatement();
+
+    return s0;
+  }
+
+  function peg$parsenumber() {
+    var s0, s1, s2, s3, s4;
+
+    peg$silentFails++;
+    s0 = peg$currPos;
+    s1 = peg$parseminus();
+    if (s1 === peg$FAILED) {
+      s1 = null;
+    }
+    s2 = peg$parseint();
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsefrac();
+      if (s3 === peg$FAILED) {
+        s3 = null;
+      }
+      s4 = peg$parseexp();
+      if (s4 === peg$FAILED) {
+        s4 = null;
+      }
+      peg$savedPos = s0;
+      s0 = peg$f0();
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+    peg$silentFails--;
+    if (s0 === peg$FAILED) {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e0); }
+    }
+
+    return s0;
+  }
+
+  function peg$parsedecimal_point() {
+    var s0;
+
+    if (input.charCodeAt(peg$currPos) === 46) {
+      s0 = peg$c0;
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e1); }
+    }
+
+    return s0;
+  }
+
+  function peg$parsedigit1_9() {
+    var s0;
+
+    if (peg$r0.test(input.charAt(peg$currPos))) {
+      s0 = input.charAt(peg$currPos);
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e2); }
+    }
+
+    return s0;
+  }
+
+  function peg$parsee() {
+    var s0;
+
+    if (peg$r1.test(input.charAt(peg$currPos))) {
+      s0 = input.charAt(peg$currPos);
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e3); }
+    }
+
+    return s0;
+  }
+
+  function peg$parseexp() {
+    var s0, s1, s2, s3, s4;
+
+    s0 = peg$currPos;
+    s1 = peg$parsee();
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parseminus();
+      if (s2 === peg$FAILED) {
+        s2 = peg$parseplus();
+      }
+      if (s2 === peg$FAILED) {
+        s2 = null;
+      }
+      s3 = [];
+      s4 = peg$parseDIGIT();
+      if (s4 !== peg$FAILED) {
+        while (s4 !== peg$FAILED) {
+          s3.push(s4);
+          s4 = peg$parseDIGIT();
+        }
+      } else {
+        s3 = peg$FAILED;
+      }
+      if (s3 !== peg$FAILED) {
+        s1 = [s1, s2, s3];
+        s0 = s1;
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsefrac() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    s1 = peg$parsedecimal_point();
+    if (s1 !== peg$FAILED) {
+      s2 = [];
+      s3 = peg$parseDIGIT();
+      if (s3 !== peg$FAILED) {
+        while (s3 !== peg$FAILED) {
+          s2.push(s3);
+          s3 = peg$parseDIGIT();
+        }
+      } else {
+        s2 = peg$FAILED;
+      }
+      if (s2 !== peg$FAILED) {
+        s1 = [s1, s2];
+        s0 = s1;
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseint() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$parsezero();
+    if (s0 === peg$FAILED) {
+      s0 = peg$currPos;
+      s1 = peg$parsedigit1_9();
+      if (s1 !== peg$FAILED) {
+        s2 = [];
+        s3 = peg$parseDIGIT();
+        while (s3 !== peg$FAILED) {
+          s2.push(s3);
+          s3 = peg$parseDIGIT();
+        }
+        s1 = [s1, s2];
+        s0 = s1;
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parseminus() {
+    var s0;
+
+    if (input.charCodeAt(peg$currPos) === 45) {
+      s0 = peg$c1;
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e4); }
+    }
+
+    return s0;
+  }
+
+  function peg$parseplus() {
+    var s0;
+
+    if (input.charCodeAt(peg$currPos) === 43) {
+      s0 = peg$c2;
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e5); }
+    }
+
+    return s0;
+  }
+
+  function peg$parsezero() {
+    var s0;
+
+    if (input.charCodeAt(peg$currPos) === 48) {
+      s0 = peg$c3;
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e6); }
+    }
+
+    return s0;
+  }
+
+  function peg$parseDIGIT() {
+    var s0;
+
+    if (peg$r2.test(input.charAt(peg$currPos))) {
+      s0 = input.charAt(peg$currPos);
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e7); }
+    }
+
+    return s0;
+  }
+
+  function peg$parsews() {
+    var s0, s1;
+
+    peg$silentFails++;
+    s0 = [];
+    if (peg$r3.test(input.charAt(peg$currPos))) {
+      s1 = input.charAt(peg$currPos);
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e9); }
+    }
+    while (s1 !== peg$FAILED) {
+      s0.push(s1);
+      if (peg$r3.test(input.charAt(peg$currPos))) {
+        s1 = input.charAt(peg$currPos);
+        peg$currPos++;
+      } else {
+        s1 = peg$FAILED;
+        if (peg$silentFails === 0) { peg$fail(peg$e9); }
+      }
+    }
+    peg$silentFails--;
+    s1 = peg$FAILED;
+    if (peg$silentFails === 0) { peg$fail(peg$e8); }
+
+    return s0;
+  }
+
+  function peg$parsecomma() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    if (input.charCodeAt(peg$currPos) === 44) {
+      s2 = peg$c4;
+      peg$currPos++;
+    } else {
+      s2 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e10); }
+    }
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsews();
+      s1 = [s1, s2, s3];
+      s0 = s1;
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsequote() {
+    var s0;
+
+    if (input.charCodeAt(peg$currPos) === 34) {
+      s0 = peg$c5;
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e11); }
+    }
+    if (s0 === peg$FAILED) {
+      if (input.charCodeAt(peg$currPos) === 39) {
+        s0 = peg$c6;
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) { peg$fail(peg$e12); }
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parsestep_char() {
+    var s0;
+
+    if (peg$r4.test(input.charAt(peg$currPos))) {
+      s0 = input.charAt(peg$currPos);
+      peg$currPos++;
+    } else {
+      s0 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e13); }
+    }
+    if (s0 === peg$FAILED) {
+      if (input.charCodeAt(peg$currPos) === 45) {
+        s0 = peg$c1;
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) { peg$fail(peg$e4); }
+      }
+      if (s0 === peg$FAILED) {
+        if (input.charCodeAt(peg$currPos) === 35) {
+          s0 = peg$c7;
+          peg$currPos++;
+        } else {
+          s0 = peg$FAILED;
+          if (peg$silentFails === 0) { peg$fail(peg$e14); }
+        }
+        if (s0 === peg$FAILED) {
+          if (input.charCodeAt(peg$currPos) === 46) {
+            s0 = peg$c0;
+            peg$currPos++;
+          } else {
+            s0 = peg$FAILED;
+            if (peg$silentFails === 0) { peg$fail(peg$e1); }
+          }
+        }
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parsestep() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    s2 = [];
+    s3 = peg$parsestep_char();
+    if (s3 !== peg$FAILED) {
+      while (s3 !== peg$FAILED) {
+        s2.push(s3);
+        s3 = peg$parsestep_char();
+      }
+    } else {
+      s2 = peg$FAILED;
+    }
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsews();
+      peg$savedPos = s0;
+      s0 = peg$f1(s2);
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesub_cycle() {
+    var s0, s1, s2, s3, s4, s5, s6, s7;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    if (input.charCodeAt(peg$currPos) === 91) {
+      s2 = peg$c8;
+      peg$currPos++;
+    } else {
+      s2 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e15); }
+    }
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsews();
+      s4 = peg$parsestack();
+      if (s4 !== peg$FAILED) {
+        s5 = peg$parsews();
+        if (input.charCodeAt(peg$currPos) === 93) {
+          s6 = peg$c9;
+          peg$currPos++;
+        } else {
+          s6 = peg$FAILED;
+          if (peg$silentFails === 0) { peg$fail(peg$e16); }
+        }
+        if (s6 !== peg$FAILED) {
+          s7 = peg$parsews();
+          peg$savedPos = s0;
+          s0 = peg$f2(s4);
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsetimeline() {
+    var s0, s1, s2, s3, s4, s5, s6, s7;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    if (input.charCodeAt(peg$currPos) === 60) {
+      s2 = peg$c10;
+      peg$currPos++;
+    } else {
+      s2 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e17); }
+    }
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsews();
+      s4 = peg$parsesingle_cycle();
+      if (s4 !== peg$FAILED) {
+        s5 = peg$parsews();
+        if (input.charCodeAt(peg$currPos) === 62) {
+          s6 = peg$c11;
+          peg$currPos++;
+        } else {
+          s6 = peg$FAILED;
+          if (peg$silentFails === 0) { peg$fail(peg$e18); }
+        }
+        if (s6 !== peg$FAILED) {
+          s7 = peg$parsews();
+          peg$savedPos = s0;
+          s0 = peg$f3(s4);
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice() {
+    var s0;
+
+    s0 = peg$parsestep();
+    if (s0 === peg$FAILED) {
+      s0 = peg$parsesub_cycle();
+      if (s0 === peg$FAILED) {
+        s0 = peg$parsetimeline();
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_modifier() {
+    var s0;
+
+    s0 = peg$parseslice_weight();
+    if (s0 === peg$FAILED) {
+      s0 = peg$parseslice_bjorklund();
+      if (s0 === peg$FAILED) {
+        s0 = peg$parseslice_slow();
+        if (s0 === peg$FAILED) {
+          s0 = peg$parseslice_fast();
+          if (s0 === peg$FAILED) {
+            s0 = peg$parseslice_fixed_step();
+          }
+        }
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_weight() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    if (input.charCodeAt(peg$currPos) === 64) {
+      s1 = peg$c12;
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e19); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsenumber();
+      if (s2 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f4(s2);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_bjorklund() {
+    var s0, s1, s2, s3, s4, s5, s6, s7, s8, s9;
+
+    s0 = peg$currPos;
+    if (input.charCodeAt(peg$currPos) === 40) {
+      s1 = peg$c13;
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e20); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        s4 = peg$parsews();
+        s5 = peg$parsecomma();
+        if (s5 !== peg$FAILED) {
+          s6 = peg$parsews();
+          s7 = peg$parsenumber();
+          if (s7 !== peg$FAILED) {
+            s8 = peg$parsews();
+            if (input.charCodeAt(peg$currPos) === 41) {
+              s9 = peg$c14;
+              peg$currPos++;
+            } else {
+              s9 = peg$FAILED;
+              if (peg$silentFails === 0) { peg$fail(peg$e21); }
+            }
+            if (s9 !== peg$FAILED) {
+              peg$savedPos = s0;
+              s0 = peg$f5(s3, s7);
+            } else {
+              peg$currPos = s0;
+              s0 = peg$FAILED;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_slow() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    if (input.charCodeAt(peg$currPos) === 47) {
+      s1 = peg$c15;
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e22); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsenumber();
+      if (s2 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f6(s2);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_fast() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    if (input.charCodeAt(peg$currPos) === 42) {
+      s1 = peg$c16;
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e23); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsenumber();
+      if (s2 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f7(s2);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_fixed_step() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    if (input.charCodeAt(peg$currPos) === 37) {
+      s1 = peg$c17;
+      peg$currPos++;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e24); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsenumber();
+      if (s2 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f8(s2);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslice_with_modifier() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    s1 = peg$parseslice();
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parseslice_modifier();
+      if (s2 === peg$FAILED) {
+        s2 = null;
+      }
+      peg$savedPos = s0;
+      s0 = peg$f9(s1, s2);
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesingle_cycle() {
+    var s0, s1, s2;
+
+    s0 = peg$currPos;
+    s1 = [];
+    s2 = peg$parseslice_with_modifier();
+    if (s2 !== peg$FAILED) {
+      while (s2 !== peg$FAILED) {
+        s1.push(s2);
+        s2 = peg$parseslice_with_modifier();
+      }
+    } else {
+      s1 = peg$FAILED;
+    }
+    if (s1 !== peg$FAILED) {
+      peg$savedPos = s0;
+      s1 = peg$f10(s1);
+    }
+    s0 = s1;
+
+    return s0;
+  }
+
+  function peg$parsestack() {
+    var s0, s1, s2, s3, s4, s5;
+
+    s0 = peg$currPos;
+    s1 = peg$parsesingle_cycle();
+    if (s1 !== peg$FAILED) {
+      s2 = [];
+      s3 = peg$currPos;
+      s4 = peg$parsecomma();
+      if (s4 !== peg$FAILED) {
+        s5 = peg$parsesingle_cycle();
+        if (s5 !== peg$FAILED) {
+          peg$savedPos = s3;
+          s3 = peg$f11(s1, s5);
+        } else {
+          peg$currPos = s3;
+          s3 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s3;
+        s3 = peg$FAILED;
+      }
+      while (s3 !== peg$FAILED) {
+        s2.push(s3);
+        s3 = peg$currPos;
+        s4 = peg$parsecomma();
+        if (s4 !== peg$FAILED) {
+          s5 = peg$parsesingle_cycle();
+          if (s5 !== peg$FAILED) {
+            peg$savedPos = s3;
+            s3 = peg$f11(s1, s5);
+          } else {
+            peg$currPos = s3;
+            s3 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s3;
+          s3 = peg$FAILED;
+        }
+      }
+      peg$savedPos = s0;
+      s0 = peg$f12(s1, s2);
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesequence() {
+    var s0, s1, s2, s3, s4;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    s2 = peg$parsequote();
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsestack();
+      if (s3 !== peg$FAILED) {
+        s4 = peg$parsequote();
+        if (s4 !== peg$FAILED) {
+          peg$savedPos = s0;
+          s0 = peg$f13(s3);
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseoperator() {
+    var s0;
+
+    s0 = peg$parsescale();
+    if (s0 === peg$FAILED) {
+      s0 = peg$parseslow();
+      if (s0 === peg$FAILED) {
+        s0 = peg$parsefast();
+        if (s0 === peg$FAILED) {
+          s0 = peg$parsetarget();
+          if (s0 === peg$FAILED) {
+            s0 = peg$parsebjorklund();
+            if (s0 === peg$FAILED) {
+              s0 = peg$parsestruct();
+              if (s0 === peg$FAILED) {
+                s0 = peg$parserotR();
+                if (s0 === peg$FAILED) {
+                  s0 = peg$parserotL();
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parsestruct() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 6) === peg$c18) {
+      s1 = peg$c18;
+      peg$currPos += 6;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e25); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsesequence_or_operator();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f14(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsetarget() {
+    var s0, s1, s2, s3, s4, s5;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 6) === peg$c19) {
+      s1 = peg$c19;
+      peg$currPos += 6;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e26); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsequote();
+      if (s3 !== peg$FAILED) {
+        s4 = peg$parsestep();
+        if (s4 !== peg$FAILED) {
+          s5 = peg$parsequote();
+          if (s5 !== peg$FAILED) {
+            peg$savedPos = s0;
+            s0 = peg$f15(s4);
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsebjorklund() {
+    var s0, s1, s2, s3, s4, s5;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 6) === peg$c20) {
+      s1 = peg$c20;
+      peg$currPos += 6;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e27); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parseint();
+      if (s3 !== peg$FAILED) {
+        s4 = peg$parsews();
+        s5 = peg$parseint();
+        if (s5 !== peg$FAILED) {
+          peg$savedPos = s0;
+          s0 = peg$f16(s3, s5);
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parseslow() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 4) === peg$c21) {
+      s1 = peg$c21;
+      peg$currPos += 4;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e28); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f17(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parserotL() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 4) === peg$c22) {
+      s1 = peg$c22;
+      peg$currPos += 4;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e29); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f18(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parserotR() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 4) === peg$c23) {
+      s1 = peg$c23;
+      peg$currPos += 4;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e30); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f19(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsefast() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 4) === peg$c24) {
+      s1 = peg$c24;
+      peg$currPos += 4;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e31); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f20(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsescale() {
+    var s0, s1, s2, s3, s4, s5;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 5) === peg$c25) {
+      s1 = peg$c25;
+      peg$currPos += 5;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e32); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsequote();
+      if (s3 !== peg$FAILED) {
+        s4 = [];
+        s5 = peg$parsestep_char();
+        if (s5 !== peg$FAILED) {
+          while (s5 !== peg$FAILED) {
+            s4.push(s5);
+            s5 = peg$parsestep_char();
+          }
+        } else {
+          s4 = peg$FAILED;
+        }
+        if (s4 !== peg$FAILED) {
+          s5 = peg$parsequote();
+          if (s5 !== peg$FAILED) {
+            peg$savedPos = s0;
+            s0 = peg$f21(s4);
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsecomment() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 2) === peg$c26) {
+      s1 = peg$c26;
+      peg$currPos += 2;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e33); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = [];
+      if (peg$r5.test(input.charAt(peg$currPos))) {
+        s3 = input.charAt(peg$currPos);
+        peg$currPos++;
+      } else {
+        s3 = peg$FAILED;
+        if (peg$silentFails === 0) { peg$fail(peg$e34); }
+      }
+      while (s3 !== peg$FAILED) {
+        s2.push(s3);
+        if (peg$r5.test(input.charAt(peg$currPos))) {
+          s3 = input.charAt(peg$currPos);
+          peg$currPos++;
+        } else {
+          s3 = peg$FAILED;
+          if (peg$silentFails === 0) { peg$fail(peg$e34); }
+        }
+      }
+      s1 = [s1, s2];
+      s0 = s1;
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsecat() {
+    var s0, s1, s2, s3, s4, s5, s6, s7, s8, s9;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 3) === peg$c27) {
+      s1 = peg$c27;
+      peg$currPos += 3;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e35); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      if (input.charCodeAt(peg$currPos) === 91) {
+        s3 = peg$c8;
+        peg$currPos++;
+      } else {
+        s3 = peg$FAILED;
+        if (peg$silentFails === 0) { peg$fail(peg$e15); }
+      }
+      if (s3 !== peg$FAILED) {
+        s4 = peg$parsews();
+        s5 = peg$parsesequence_or_operator();
+        if (s5 !== peg$FAILED) {
+          s6 = [];
+          s7 = peg$currPos;
+          s8 = peg$parsecomma();
+          if (s8 !== peg$FAILED) {
+            s9 = peg$parsesequence_or_operator();
+            if (s9 !== peg$FAILED) {
+              peg$savedPos = s7;
+              s7 = peg$f22(s5, s9);
+            } else {
+              peg$currPos = s7;
+              s7 = peg$FAILED;
+            }
+          } else {
+            peg$currPos = s7;
+            s7 = peg$FAILED;
+          }
+          while (s7 !== peg$FAILED) {
+            s6.push(s7);
+            s7 = peg$currPos;
+            s8 = peg$parsecomma();
+            if (s8 !== peg$FAILED) {
+              s9 = peg$parsesequence_or_operator();
+              if (s9 !== peg$FAILED) {
+                peg$savedPos = s7;
+                s7 = peg$f22(s5, s9);
+              } else {
+                peg$currPos = s7;
+                s7 = peg$FAILED;
+              }
+            } else {
+              peg$currPos = s7;
+              s7 = peg$FAILED;
+            }
+          }
+          s7 = peg$parsews();
+          if (input.charCodeAt(peg$currPos) === 93) {
+            s8 = peg$c9;
+            peg$currPos++;
+          } else {
+            s8 = peg$FAILED;
+            if (peg$silentFails === 0) { peg$fail(peg$e16); }
+          }
+          if (s8 !== peg$FAILED) {
+            peg$savedPos = s0;
+            s0 = peg$f23(s5, s6);
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesequence_or_group() {
+    var s0;
+
+    s0 = peg$parsecat();
+    if (s0 === peg$FAILED) {
+      s0 = peg$parsesequence();
+    }
+
+    return s0;
+  }
+
+  function peg$parsesequence_or_operator() {
+    var s0, s1, s2, s3, s4, s5;
+
+    s0 = peg$currPos;
+    s1 = peg$parsesequence_or_group();
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = [];
+      s4 = peg$parsecomment();
+      while (s4 !== peg$FAILED) {
+        s3.push(s4);
+        s4 = peg$parsecomment();
+      }
+      peg$savedPos = s0;
+      s0 = peg$f24(s1);
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+    if (s0 === peg$FAILED) {
+      s0 = peg$currPos;
+      s1 = peg$parseoperator();
+      if (s1 !== peg$FAILED) {
+        s2 = peg$parsews();
+        if (input.charCodeAt(peg$currPos) === 36) {
+          s3 = peg$c28;
+          peg$currPos++;
+        } else {
+          s3 = peg$FAILED;
+          if (peg$silentFails === 0) { peg$fail(peg$e36); }
+        }
+        if (s3 !== peg$FAILED) {
+          s4 = peg$parsews();
+          s5 = peg$parsesequence_or_operator();
+          if (s5 !== peg$FAILED) {
+            peg$savedPos = s0;
+            s0 = peg$f25(s1, s5);
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    }
+
+    return s0;
+  }
+
+  function peg$parsesequ_or_operator_or_comment() {
+    var s0, s1;
+
+    s0 = peg$currPos;
+    s1 = peg$parsesequence_or_operator();
+    if (s1 !== peg$FAILED) {
+      peg$savedPos = s0;
+      s1 = peg$f26(s1);
+    }
+    s0 = s1;
+    if (s0 === peg$FAILED) {
+      s0 = peg$parsecomment();
+    }
+
+    return s0;
+  }
+
+  function peg$parsesequence_definition() {
+    var s0;
+
+    s0 = peg$parsesequ_or_operator_or_comment();
+
+    return s0;
+  }
+
+  function peg$parsecommand() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    s1 = peg$parsews();
+    s2 = peg$parsesetcps();
+    if (s2 === peg$FAILED) {
+      s2 = peg$parsesetbpm();
+      if (s2 === peg$FAILED) {
+        s2 = peg$parsehush();
+      }
+    }
+    if (s2 !== peg$FAILED) {
+      s3 = peg$parsews();
+      peg$savedPos = s0;
+      s0 = peg$f27(s2);
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesetcps() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 6) === peg$c29) {
+      s1 = peg$c29;
+      peg$currPos += 6;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e37); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f28(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsesetbpm() {
+    var s0, s1, s2, s3;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 6) === peg$c30) {
+      s1 = peg$c30;
+      peg$currPos += 6;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e38); }
+    }
+    if (s1 !== peg$FAILED) {
+      s2 = peg$parsews();
+      s3 = peg$parsenumber();
+      if (s3 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s0 = peg$f29(s3);
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+    } else {
+      peg$currPos = s0;
+      s0 = peg$FAILED;
+    }
+
+    return s0;
+  }
+
+  function peg$parsehush() {
+    var s0, s1;
+
+    s0 = peg$currPos;
+    if (input.substr(peg$currPos, 4) === peg$c31) {
+      s1 = peg$c31;
+      peg$currPos += 4;
+    } else {
+      s1 = peg$FAILED;
+      if (peg$silentFails === 0) { peg$fail(peg$e39); }
+    }
+    if (s1 !== peg$FAILED) {
+      peg$savedPos = s0;
+      s1 = peg$f30();
+    }
+    s0 = s1;
+
+    return s0;
+  }
+
+  function peg$parsestatement() {
+    var s0;
+
+    s0 = peg$parsesequence_definition();
+    if (s0 === peg$FAILED) {
+      s0 = peg$parsecommand();
+    }
+
+    return s0;
+  }
+
+
+    var PatternStub = function(source, alignment)
+    {
+      this.type_ = "pattern";
+      this.arguments_ = { alignment : alignment};
+      this.source_ = source;
+    }
+
+    var OperatorStub = function(name, args, source)
+    {
+      this.type_ = name;
+      this.arguments_ = args;
+      this.source_ = source;
+    }
+
+    var ElementStub = function(source, options)
+    {
+      this.type_ = "element";
+      this.source_ = source;
+      this.options_ = options;
+    }
+
+    var CommandStub = function(name, options)
+    {
+      this.type_ = "command";
+      this.name_ = name;
+      this.options_ = options;
+    }
+
+
+
+  peg$result = peg$startRuleFunction();
+
+  if (peg$result !== peg$FAILED && peg$currPos === input.length) {
+    return peg$result;
+  } else {
+    if (peg$result !== peg$FAILED && peg$currPos < input.length) {
+      peg$fail(peg$endExpectation());
+    }
+
+    throw peg$buildStructuredError(
+      peg$maxFailExpected,
+      peg$maxFailPos < input.length ? input.charAt(peg$maxFailPos) : null,
+      peg$maxFailPos < input.length
+        ? peg$computeLocation(peg$maxFailPos, peg$maxFailPos + 1)
+        : peg$computeLocation(peg$maxFailPos, peg$maxFailPos)
+    );
+  }
+}
+
+export {
+  peg$SyntaxError as SyntaxError,
+  peg$parse as parse
+};
diff --git a/repl/krill.pegjs b/repl/krill.pegjs
new file mode 100644
index 00000000..e32a9763
--- /dev/null
+++ b/repl/krill.pegjs
@@ -0,0 +1,207 @@
+// Some terminology:
+// a sequence = a serie of elements placed between quotes
+// a stack = a serie of vertically aligned slices sharing the same overall length
+// a slice = a serie of horizontally aligned elements
+
+
+{
+  var PatternStub = function(source, alignment)
+  {
+    this.type_ = "pattern";
+    this.arguments_ = { alignment : alignment};
+    this.source_ = source;
+  }
+
+  var OperatorStub = function(name, args, source)
+  {
+    this.type_ = name;
+    this.arguments_ = args;
+    this.source_ = source;
+  }
+
+  var ElementStub = function(source, options)
+  {
+    this.type_ = "element";
+    this.source_ = source;
+    this.options_ = options;
+  }
+
+  var CommandStub = function(name, options)
+  {
+    this.type_ = "command";
+    this.name_ = name;
+    this.options_ = options;
+  }
+
+}
+
+start = statement
+
+// ----- Numbers -----
+
+number "number"
+  = minus? int frac? exp? { return parseFloat(text()); }
+
+decimal_point
+  = "."
+
+digit1_9
+  = [1-9]
+
+e
+  = [eE]
+
+exp
+  = e (minus / plus)? DIGIT+
+
+frac
+  = decimal_point DIGIT+
+
+int
+  = zero / (digit1_9 DIGIT*)
+
+minus
+  = "-"
+
+plus
+  = "+"
+
+zero
+  = "0"
+
+DIGIT  = [0-9]
+
+// ------------------ delimiters ---------------------------
+
+ws "whitespace" = [ \n\r\t]*
+comma = ws "," ws;
+quote = '"' / "'"
+
+// ------------------ steps and cycles ---------------------------
+
+// single step definition (e.g bd)
+step_char =  [0-9a-zA-Z~] / "-" / "#" / "."
+step = ws chars:step_char+ ws { return chars.join("") }
+
+// define a sub cycle e.g. [1 2, 3 [4]]
+sub_cycle = ws  "[" ws s:stack ws "]" ws { return s}
+
+// define a timeline e.g <1 3 [3 5]>. We simply defer to a stack and change the alignement
+timeline = ws "<" ws sc:single_cycle ws ">" ws
+  { sc.arguments_.alignment = "t"; return sc;}
+
+// a slice is either a single step or a sub cycle
+slice = step / sub_cycle  / timeline
+
+// slice modifier affects the timing/size of a slice (e.g. [a b c]@3)
+// at this point, we assume we can represent them as regular sequence operators
+slice_modifier = slice_weight / slice_bjorklund / slice_slow / slice_fast / slice_fixed_step
+
+slice_weight =  "@" a:number
+  { return { weight: a} }
+
+slice_bjorklund = "(" ws p:number ws comma ws s:number ws")"
+  { return { operator : { type_: "bjorklund", arguments_ :{ pulse: p, step:s } } } }
+
+slice_slow = "/"a:number
+  { return { operator : { type_: "stretch", arguments_ :{ amount:a } } } }
+
+slice_fast = "*"a:number
+  { return { operator : { type_: "stretch", arguments_ :{ amount:"1/"+a } } } }
+
+slice_fixed_step = "%"a:number
+  { return { operator : { type_: "fixed-step", arguments_ :{ amount:a } } } }
+
+// a slice with an modifier applied i.e [bd@4 sd@3]@2 hh]
+slice_with_modifier = s:slice o:slice_modifier?
+  { return new ElementStub(s, o);}
+
+// a single cycle is a combination of one or more successive slices (as an array). If we
+// have only one element, we skip the array and return the element itself
+single_cycle = s:(slice_with_modifier)+
+  { return new PatternStub(s,"h"); }
+
+// a stack is a serie of vertically aligned single cycles, separated by a comma
+// if the stack contains only one element, we don't create a stack but return the
+// underlying element
+stack = c:single_cycle cs:(comma v:single_cycle { return v})*
+  { if (cs.length == 0 && c instanceof Object) { return c;} else { cs.unshift(c); return new PatternStub(cs,"v");}  }
+
+// a sequence is a quoted stack
+sequence = ws quote s:stack quote
+  { return s; }
+
+// ------------------ operators ---------------------------
+
+operator = scale / slow / fast / target / bjorklund / struct / rotR / rotL
+
+struct = "struct" ws s:sequence_or_operator
+  { return { name: "struct", args: { sequence:s }}}
+
+target = "target" ws quote s:step quote
+  { return { name: "target", args : { name:s}}}
+
+bjorklund = "euclid" ws p:int ws s:int
+  { return { name: "bjorklund", args :{ pulse: parseInt(p), step:parseInt(s) }}}
+
+slow = "slow" ws a:number
+  { return { name: "stretch", args :{ amount: a}}}
+
+rotL = "rotL" ws a:number
+  { return { name: "shift", args :{ amount: "-"+a}}}
+
+rotR = "rotR" ws a:number
+  { return { name: "shift", args :{ amount: a}}}
+
+fast = "fast" ws a:number
+  { return { name: "stretch", args :{ amount: "1/"+a}}}
+
+scale = "scale" ws quote s:(step_char)+ quote
+{ return { name: "scale", args :{ scale: s.join("")}}}
+
+comment = '//' p:([^\n]*)
+
+// ---------------- grouping --------------------------------
+
+group_operator = cat
+
+// cat is another form of timeline
+cat = "cat" ws "[" ws  s:sequence_or_operator ss:(comma v:sequence_or_operator { return v})* ws "]"
+  { ss.unshift(s); return new PatternStub(ss,"t"); }
+
+// ------------------ high level sequence ---------------------------
+
+sequence_or_group =
+  group_operator /
+  sequence
+
+sequence_or_operator =
+  sg:sequence_or_group ws (comment)*
+    {return sg}
+  / o:operator ws "$" ws soc:sequence_or_operator
+    { return new OperatorStub(o.name,o.args,soc)}
+
+sequ_or_operator_or_comment =
+  sc: sequence_or_operator
+    { return sc }
+   / comment
+
+sequence_definition = s:sequ_or_operator_or_comment
+
+// ---------------------- statements ----------------------------
+
+command = ws c:(setcps / setbpm / hush) ws
+  { return c }
+
+setcps = "setcps" ws v:number
+  { return new CommandStub("setcps", { value: v})}
+
+setbpm = "setbpm" ws v:number
+  { return new CommandStub("setcps", { value: (v/120/2)})}
+
+hush = "hush"
+  { return new CommandStub("hush")}
+
+// ---------------------- statements ----------------------------
+
+statement = sequence_definition / command
diff --git a/repl/package-lock.json b/repl/package-lock.json
index 6ffdd90a..a08c11c7 100644
--- a/repl/package-lock.json
+++ b/repl/package-lock.json
@@ -25,6 +25,8 @@
         "@web/test-runner": "^0.13.3",
         "autoprefixer": "^10.4.2",
         "chai": "^4.3.4",
+        "peggy": "^1.2.0",
+        "pegjs": "^0.10.0",
         "postcss": "^8.4.6",
         "prettier": "^2.2.1",
         "snowpack": "^3.3.7",
@@ -6067,6 +6069,30 @@
         "node": "*"
       }
     },
+    "node_modules/peggy": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/peggy/-/peggy-1.2.0.tgz",
+      "integrity": "sha512-PQ+NKpAobImfMprYQtc4Egmyi29bidRGEX0kKjCU5uuW09s0Cthwqhfy7mLkwcB4VcgacE5L/ZjruD/kOPCUUw==",
+      "dev": true,
+      "bin": {
+        "peggy": "bin/peggy"
+      },
+      "engines": {
+        "node": ">=10"
+      }
+    },
+    "node_modules/pegjs": {
+      "version": "0.10.0",
+      "resolved": "https://registry.npmjs.org/pegjs/-/pegjs-0.10.0.tgz",
+      "integrity": "sha1-z4uvrm7d/0tafvsYUmnqr0YQ3b0=",
+      "dev": true,
+      "bin": {
+        "pegjs": "bin/pegjs"
+      },
+      "engines": {
+        "node": ">=0.10"
+      }
+    },
     "node_modules/pend": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/pend/-/pend-1.2.0.tgz",
@@ -13113,6 +13139,18 @@
       "integrity": "sha512-Dp6zGqpTdETdR63lehJYPeIOqpiNBNtc7BpWSLrOje7UaIsE5aY92r/AunQA7rsXvet3lrJ3JnZX29UPTKXyKQ==",
       "dev": true
     },
+    "peggy": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/peggy/-/peggy-1.2.0.tgz",
+      "integrity": "sha512-PQ+NKpAobImfMprYQtc4Egmyi29bidRGEX0kKjCU5uuW09s0Cthwqhfy7mLkwcB4VcgacE5L/ZjruD/kOPCUUw==",
+      "dev": true
+    },
+    "pegjs": {
+      "version": "0.10.0",
+      "resolved": "https://registry.npmjs.org/pegjs/-/pegjs-0.10.0.tgz",
+      "integrity": "sha1-z4uvrm7d/0tafvsYUmnqr0YQ3b0=",
+      "dev": true
+    },
     "pend": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/pend/-/pend-1.2.0.tgz",
diff --git a/repl/package.json b/repl/package.json
index eabaec9d..e6c8dc39 100644
--- a/repl/package.json
+++ b/repl/package.json
@@ -4,7 +4,8 @@
     "build": "snowpack build && cp ./public/.nojekyll ../docs",
     "test": "web-test-runner \"src/**/*.test.tsx\"",
     "format": "prettier --write \"src/**/*.{js,jsx,ts,tsx}\"",
-    "lint": "prettier --check \"src/**/*.{js,jsx,ts,tsx}\""
+    "lint": "prettier --check \"src/**/*.{js,jsx,ts,tsx}\"",
+    "peggy": "peggy -o krill-parser.js --format es ./krill.pegjs"
   },
   "dependencies": {
     "react": "^17.0.2",
@@ -27,6 +28,7 @@
     "@web/test-runner": "^0.13.3",
     "autoprefixer": "^10.4.2",
     "chai": "^4.3.4",
+    "peggy": "^1.2.0",
     "postcss": "^8.4.6",
     "prettier": "^2.2.1",
     "snowpack": "^3.3.7",
diff --git a/repl/src/App.tsx b/repl/src/App.tsx
index c2770173..18d9e797 100644
--- a/repl/src/App.tsx
+++ b/repl/src/App.tsx
@@ -6,15 +6,11 @@ import * as Tone from 'tone';
 import useCycle from './useCycle';
 import type { Hap, Pattern } from './types';
 import { tetris } from './tunes';
+import _mini from './mini';
 
-const { Fraction, TimeSpan } = strudel;
-
-const fr = (v: number) => new Fraction(v);
-const ts = (start: number, end: number) => new TimeSpan(fr(start), fr(end));
-const parse = (code: string): Pattern => {
-  const { sequence, pure, reify, slowcat, fastcat, cat, stack, silence } = strudel; // make available to eval
-  return eval(code);
-};
+const { sequence, pure, reify, slowcat, fastcat, cat, stack, silence } = strudel; // make available to eval
+const mini = _mini; // for eval (direct import wont work somehow)
+const parse = (code: string): Pattern => eval(code);
 
 const synth = new Tone.PolySynth().toDestination();
 synth.set({
diff --git a/repl/src/mini.ts b/repl/src/mini.ts
new file mode 100644
index 00000000..b56baf8c
--- /dev/null
+++ b/repl/src/mini.ts
@@ -0,0 +1,34 @@
+import * as krill from '../krill-parser';
+import * as strudel from '../../strudel.mjs';
+
+export function patternifyAST(ast: any): any {
+  switch (ast.type_) {
+    case 'pattern':
+      return strudel.sequence(...ast.source_.map(patternifyAST));
+    case 'element':
+      if (typeof ast.source_ !== 'object') {
+        return ast.source_;
+      }
+      return patternifyAST(ast.source_);
+  }
+}
+export default (str: string) => patternifyAST(krill.parse(`"${str}"`));
+
+/* 
+TODO:
+export interface Arguments {
+  alignment: string;
+}
+
+export interface ElementStub {
+  type_: string;
+  source_: string;
+  options_?: any;
+}
+
+export interface PatternStub {
+  type_: string; // pattern
+  arguments_: Arguments;
+  source_: ElementStub[];
+}
+ */