add parser

6 files changed, 963 insertions, 1 deletions

diff --git a/src/interpreter/PeggyParser.js b/src/interpreter/PeggyParser.js
new file mode 100644
index 0000000..5671d91
--- /dev/null
+++ b/src/interpreter/PeggyParser.js
@@ -0,0 +1,896 @@
+// @generated by Peggy 4.0.2.
+//
+// https://peggyjs.org/
+export default (function () {
+  "use strict";
+
+  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);
+    // istanbul ignore next Check is a necessary evil to support older environments
+    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$SyntaxError.prototype.format = function (sources) {
+    var str = "Error: " + this.message;
+    if (this.location) {
+      var src = null;
+      var k;
+      for (k = 0; k < sources.length; k++) {
+        if (sources[k].source === this.location.source) {
+          src = sources[k].text.split(/\r\n|\n|\r/g);
+          break;
+        }
+      }
+      var s = this.location.start;
+      var offset_s =
+        this.location.source &&
+        typeof this.location.source.offset === "function"
+          ? this.location.source.offset(s)
+          : s;
+      var loc =
+        this.location.source + ":" + offset_s.line + ":" + offset_s.column;
+      if (src) {
+        var e = this.location.end;
+        var filler = peg$padEnd("", offset_s.line.toString().length, " ");
+        var line = src[s.line - 1];
+        var last = s.line === e.line ? e.column : line.length + 1;
+        var hatLen = last - s.column || 1;
+        str +=
+          "\n --> " +
+          loc +
+          "\n" +
+          filler +
+          " |\n" +
+          offset_s.line +
+          " | " +
+          line +
+          "\n" +
+          filler +
+          " | " +
+          peg$padEnd("", s.column - 1, " ") +
+          peg$padEnd("", hatLen, "^");
+      } 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.join("") + "]"
+        );
+      },
+
+      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 = { LambdaTerm: peg$parseLambdaTerm };
+    var peg$startRuleFunction = peg$parseLambdaTerm;
+
+    var peg$c0 = "(";
+    var peg$c1 = ")";
+    var peg$c2 = ".";
+    var peg$c3 = "\r\n";
+
+    var peg$r0 = /^[a-zA-Z0-9]/;
+    var peg$r1 = /^[\\\u03BB]/;
+    var peg$r2 = /^[\t-\n ]/;
+
+    var peg$e0 = peg$classExpectation(
+      [
+        ["a", "z"],
+        ["A", "Z"],
+        ["0", "9"],
+      ],
+      false,
+      false,
+    );
+    var peg$e1 = peg$literalExpectation("(", false);
+    var peg$e2 = peg$literalExpectation(")", false);
+    var peg$e3 = peg$literalExpectation(".", false);
+    var peg$e4 = peg$classExpectation(["\\", "\u03BB"], false, false);
+    var peg$e5 = peg$classExpectation([["\t", "\n"], " "], false, false);
+    var peg$e6 = peg$literalExpectation("\r\n", false);
+
+    var peg$f0 = function (left, argList, lastArg) {
+      const args =
+        lastArg || argList.length ? [...argList.map((x) => x[0]), lastArg] : [];
+      return { application: { left, args } };
+    };
+    var peg$f1 = function (param, body) {
+      return { abstraction: { param, body } };
+    };
+    var peg$f2 = function (param) {
+      return param.join("");
+    };
+    var peg$currPos = options.peg$currPos | 0;
+    var peg$savedPos = peg$currPos;
+    var peg$posDetailsCache = [{ line: 1, column: 1 }];
+    var peg$maxFailPos = peg$currPos;
+    var peg$maxFailExpected = options.peg$maxFailExpected || [];
+    var peg$silentFails = options.peg$silentFails | 0;
+
+    var peg$resultsCache = {};
+
+    var peg$result;
+
+    if (options.startRule) {
+      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 {
+        if (pos >= peg$posDetailsCache.length) {
+          p = peg$posDetailsCache.length - 1;
+        } else {
+          p = pos;
+          while (!peg$posDetailsCache[--p]) {}
+        }
+
+        details = peg$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, offset) {
+      var startPosDetails = peg$computePosDetails(startPos);
+      var endPosDetails = peg$computePosDetails(endPos);
+
+      var res = {
+        source: peg$source,
+        start: {
+          offset: startPos,
+          line: startPosDetails.line,
+          column: startPosDetails.column,
+        },
+        end: {
+          offset: endPos,
+          line: endPosDetails.line,
+          column: endPosDetails.column,
+        },
+      };
+      if (offset && peg$source && typeof peg$source.offset === "function") {
+        res.start = peg$source.offset(res.start);
+        res.end = peg$source.offset(res.end);
+      }
+      return res;
+    }
+
+    function peg$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$SyntaxError.buildMessage(expected, found),
+        expected,
+        found,
+        location,
+      );
+    }
+
+    function peg$parseLambdaTerm() {
+      var s0;
+
+      var key = peg$currPos * 9 + 0;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = peg$parseApplication();
+      if (s0 === peg$FAILED) {
+        s0 = peg$parseAbstraction();
+        if (s0 === peg$FAILED) {
+          s0 = peg$parseVariable();
+        }
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseApplication() {
+      var s0, s1, s2, s3, s4, s5, s6, s7, s8;
+
+      var key = peg$currPos * 9 + 1;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = peg$currPos;
+      s1 = peg$parseLPAREN();
+      if (s1 !== peg$FAILED) {
+        s2 = peg$parse_();
+        if (s2 === peg$FAILED) {
+          s2 = null;
+        }
+        s3 = peg$parseLambdaTerm();
+        if (s3 !== peg$FAILED) {
+          s4 = peg$parse_();
+          if (s4 !== peg$FAILED) {
+            s5 = [];
+            s6 = peg$currPos;
+            s7 = peg$parseLambdaTerm();
+            if (s7 !== peg$FAILED) {
+              s8 = peg$parse_();
+              if (s8 !== peg$FAILED) {
+                s7 = [s7, s8];
+                s6 = s7;
+              } else {
+                peg$currPos = s6;
+                s6 = peg$FAILED;
+              }
+            } else {
+              peg$currPos = s6;
+              s6 = peg$FAILED;
+            }
+            while (s6 !== peg$FAILED) {
+              s5.push(s6);
+              s6 = peg$currPos;
+              s7 = peg$parseLambdaTerm();
+              if (s7 !== peg$FAILED) {
+                s8 = peg$parse_();
+                if (s8 !== peg$FAILED) {
+                  s7 = [s7, s8];
+                  s6 = s7;
+                } else {
+                  peg$currPos = s6;
+                  s6 = peg$FAILED;
+                }
+              } else {
+                peg$currPos = s6;
+                s6 = peg$FAILED;
+              }
+            }
+            s6 = peg$parseLambdaTerm();
+            if (s6 !== peg$FAILED) {
+              s7 = peg$parse_();
+              if (s7 === peg$FAILED) {
+                s7 = null;
+              }
+              s8 = peg$parseRPAREN();
+              if (s8 !== peg$FAILED) {
+                peg$savedPos = s0;
+                s0 = peg$f0(s3, 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;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseAbstraction() {
+      var s0, s1, s2, s3, s4, s5, s6, s7, s8, s9, s10, s11, s12, s13, s14, s15;
+
+      var key = peg$currPos * 9 + 2;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = peg$currPos;
+      s1 = peg$parseLPAREN();
+      if (s1 !== peg$FAILED) {
+        s2 = peg$parse_();
+        if (s2 === peg$FAILED) {
+          s2 = null;
+        }
+        s3 = peg$parseLAMBDA();
+        if (s3 !== peg$FAILED) {
+          s4 = peg$parse_();
+          if (s4 === peg$FAILED) {
+            s4 = null;
+          }
+          s5 = peg$parseLPAREN();
+          if (s5 !== peg$FAILED) {
+            s6 = peg$parse_();
+            if (s6 === peg$FAILED) {
+              s6 = null;
+            }
+            s7 = peg$parseVariable();
+            if (s7 !== peg$FAILED) {
+              s8 = peg$parse_();
+              if (s8 === peg$FAILED) {
+                s8 = null;
+              }
+              s9 = peg$parseRPAREN();
+              if (s9 !== peg$FAILED) {
+                s10 = peg$parse_();
+                if (s10 === peg$FAILED) {
+                  s10 = null;
+                }
+                s11 = peg$parseDOT();
+                if (s11 !== peg$FAILED) {
+                  s12 = peg$parse_();
+                  if (s12 === peg$FAILED) {
+                    s12 = null;
+                  }
+                  s13 = peg$parseLambdaTerm();
+                  if (s13 !== peg$FAILED) {
+                    s14 = peg$parse_();
+                    if (s14 === peg$FAILED) {
+                      s14 = null;
+                    }
+                    s15 = peg$parseRPAREN();
+                    if (s15 !== peg$FAILED) {
+                      peg$savedPos = s0;
+                      s0 = peg$f1(s7, s13);
+                    } else {
+                      peg$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$FAILED;
+            }
+          } else {
+            peg$currPos = s0;
+            s0 = peg$FAILED;
+          }
+        } else {
+          peg$currPos = s0;
+          s0 = peg$FAILED;
+        }
+      } else {
+        peg$currPos = s0;
+        s0 = peg$FAILED;
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseVariable() {
+      var s0, s1, s2;
+
+      var key = peg$currPos * 9 + 3;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = peg$currPos;
+      s1 = [];
+      s2 = input.charAt(peg$currPos);
+      if (peg$r0.test(s2)) {
+        peg$currPos++;
+      } else {
+        s2 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e0);
+        }
+      }
+      if (s2 !== peg$FAILED) {
+        while (s2 !== peg$FAILED) {
+          s1.push(s2);
+          s2 = input.charAt(peg$currPos);
+          if (peg$r0.test(s2)) {
+            peg$currPos++;
+          } else {
+            s2 = peg$FAILED;
+            if (peg$silentFails === 0) {
+              peg$fail(peg$e0);
+            }
+          }
+        }
+      } else {
+        s1 = peg$FAILED;
+      }
+      if (s1 !== peg$FAILED) {
+        peg$savedPos = s0;
+        s1 = peg$f2(s1);
+      }
+      s0 = s1;
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseLPAREN() {
+      var s0;
+
+      var key = peg$currPos * 9 + 4;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      if (input.charCodeAt(peg$currPos) === 40) {
+        s0 = peg$c0;
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e1);
+        }
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseRPAREN() {
+      var s0;
+
+      var key = peg$currPos * 9 + 5;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      if (input.charCodeAt(peg$currPos) === 41) {
+        s0 = peg$c1;
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e2);
+        }
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseDOT() {
+      var s0;
+
+      var key = peg$currPos * 9 + 6;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      if (input.charCodeAt(peg$currPos) === 46) {
+        s0 = peg$c2;
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e3);
+        }
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parseLAMBDA() {
+      var s0;
+
+      var key = peg$currPos * 9 + 7;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = input.charAt(peg$currPos);
+      if (peg$r1.test(s0)) {
+        peg$currPos++;
+      } else {
+        s0 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e4);
+        }
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    function peg$parse_() {
+      var s0, s1;
+
+      var key = peg$currPos * 9 + 8;
+      var cached = peg$resultsCache[key];
+
+      if (cached) {
+        peg$currPos = cached.nextPos;
+
+        return cached.result;
+      }
+
+      s0 = [];
+      s1 = input.charAt(peg$currPos);
+      if (peg$r2.test(s1)) {
+        peg$currPos++;
+      } else {
+        s1 = peg$FAILED;
+        if (peg$silentFails === 0) {
+          peg$fail(peg$e5);
+        }
+      }
+      if (s1 === peg$FAILED) {
+        if (input.substr(peg$currPos, 2) === peg$c3) {
+          s1 = peg$c3;
+          peg$currPos += 2;
+        } else {
+          s1 = peg$FAILED;
+          if (peg$silentFails === 0) {
+            peg$fail(peg$e6);
+          }
+        }
+      }
+      if (s1 !== peg$FAILED) {
+        while (s1 !== peg$FAILED) {
+          s0.push(s1);
+          s1 = input.charAt(peg$currPos);
+          if (peg$r2.test(s1)) {
+            peg$currPos++;
+          } else {
+            s1 = peg$FAILED;
+            if (peg$silentFails === 0) {
+              peg$fail(peg$e5);
+            }
+          }
+          if (s1 === peg$FAILED) {
+            if (input.substr(peg$currPos, 2) === peg$c3) {
+              s1 = peg$c3;
+              peg$currPos += 2;
+            } else {
+              s1 = peg$FAILED;
+              if (peg$silentFails === 0) {
+                peg$fail(peg$e6);
+              }
+            }
+          }
+        }
+      } else {
+        s0 = peg$FAILED;
+      }
+
+      peg$resultsCache[key] = { nextPos: peg$currPos, result: s0 };
+
+      return s0;
+    }
+
+    peg$result = peg$startRuleFunction();
+
+    if (options.peg$library) {
+      return /** @type {any} */ ({
+        peg$result,
+        peg$currPos,
+        peg$FAILED,
+        peg$maxFailExpected,
+        peg$maxFailPos,
+      });
+    }
+    if (peg$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$maxFailPos),
+      );
+    }
+  }
+
+  return {
+    StartRules: ["LambdaTerm"],
+    SyntaxError: peg$SyntaxError,
+    parse: peg$parse,
+  };
+})();
diff --git a/src/interpreter/grammar.pegjs b/src/interpreter/grammar.pegjs
new file mode 100644
index 0000000..520d6c8
--- /dev/null
+++ b/src/interpreter/grammar.pegjs
@@ -0,0 +1,17 @@
+LambdaTerm = Application / Abstraction / Variable
+
+Application = LPAREN _? left:LambdaTerm _ argList:(LambdaTerm _)* lastArg:LambdaTerm _? RPAREN { 
+  const args = lastArg || argList.length ? [...argList.map(x => x[0]), lastArg] : [];
+  return { application: { left, args } };
+}
+
+Abstraction = LPAREN _? LAMBDA _? LPAREN _? param:Variable _? RPAREN _? DOT _? body:LambdaTerm _? RPAREN { return { abstraction: { param, body } }; }
+
+Variable = param:[a-zA-Z0-9]+ { return param.join(""); }
+
+LPAREN = "("
+RPAREN = ")"
+DOT = "."
+LAMBDA = "λ" / "\\"
+
+_ = ("\n" / " " / "\t" / "\r\n")+
\ No newline at end of file
diff --git a/src/interpreter/index.ts b/src/interpreter/index.ts
new file mode 100644
index 0000000..20d0327
--- /dev/null
+++ b/src/interpreter/index.ts
@@ -0,0 +1,2 @@
+export * from "./parser";
+export * from "./interpreter";
diff --git a/src/interpreter/interpreter.ts b/src/interpreter/interpreter.ts
new file mode 100644
index 0000000..c16984f
--- /dev/null
+++ b/src/interpreter/interpreter.ts
@@ -0,0 +1,10 @@
+import { parse, type LambdaTerm } from ".";
+
+export const evaluate = (_term: LambdaTerm): LambdaTerm => {
+  return "";
+};
+
+export const interpret = (term: string): LambdaTerm => {
+  const ast = parse(term);
+  return evaluate(ast);
+};
diff --git a/src/interpreter/parser.ts b/src/interpreter/parser.ts
new file mode 100644
index 0000000..ea07796
--- /dev/null
+++ b/src/interpreter/parser.ts
@@ -0,0 +1,35 @@
+import peggyParser from "./PeggyParser.js";
+
+export type Application = {
+  application: {
+    left: LambdaTerm;
+    args: Array<LambdaTerm>;
+  };
+};
+
+export type Abstraction = {
+  abstraction: {
+    param: Variable;
+    body: LambdaTerm;
+  };
+};
+
+export type Variable = string;
+
+export type LambdaTerm = Application | Abstraction | Variable;
+
+export const isApplication = (term: LambdaTerm): term is Application => {
+  return (term as Application).application !== undefined;
+};
+
+export const isAbstraction = (term: LambdaTerm): term is Abstraction => {
+  return (term as Abstraction).abstraction !== undefined;
+};
+
+export const isVariable = (term: LambdaTerm): term is Variable => {
+  return typeof term === "string";
+};
+
+export const parse = (term: string) => {
+  return peggyParser.parse(term, { library: true });
+};
diff --git a/tsconfig.json b/tsconfig.json
index a7fc6fb..45d202f 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -18,7 +18,9 @@
     "strict": true,
     "noUnusedLocals": true,
     "noUnusedParameters": true,
-    "noFallthroughCasesInSwitch": true
+    "noFallthroughCasesInSwitch": true,
+
+    "allowJs": true
   },
   "include": ["src"],
   "references": [{ "path": "./tsconfig.node.json" }]