1 Here are the definitions pre-loaded for working on assignment 3:
4 <textarea id="INPUT" style="border: 2px solid black; color: black; font-family: monospace; height: 3in; overflow: auto; padding: 0.5em; width: 100%;">
8 let and = \l r. l (r true false) false in
9 let make_pair = \f s g. g f s in
12 let empty = make_pair true junk in
13 let isempty = \x. x fst in
14 let make_list = \h t. make_pair false (make_pair h t) in
15 let head = \l. isempty l err (l snd fst) in
16 let tail = \l. isempty l err (l snd snd) in
18 ; a list of numbers to experiment on
19 let mylist = make_list 1 (make_list 2 (make_list 3 empty)) in
22 let iszero = \n. n (\x. false) true in
23 let succ = \n s z. s (n s z) in
24 let mul = \m n s. m (n s) in
25 let pred = \n. iszero n 0 (length (tail (n (\p. make_list junk p) empty))) in
26 let leq = \m n. iszero(n pred m) in
27 let eq = \m n. and (leq m n)(leq n m) in
29 ; a fixed-point combinator for defining recursive functions
30 let Y = \f. (\h. f (h h)) (\h. f (h h)) in
32 let length = Y (\length l. isempty l 0 (succ (length (tail l)))) in
35 let makePair = make_pair in
37 let isNil = isempty in
38 let makeList = make_list in
39 let isZero = iszero in
45 <input id="PARSE" value="Normalize" type="button">
46 <input id="ETA" type="checkbox">do eta-reductions too
47 <noscript><p>You may not see it because you have JavaScript turned off. Uffff!</p></noscript>
48 <script src="/code/lambda.js"></script>
49 <script src="/code/tokens.js"></script>
50 <script src="/code/parse.js"></script>
51 <script src="/code/json2.js"></script>
55 /*jslint evil: true */
57 /*members create, error, message, name, prototype, stringify, toSource,
61 /*global JSON, make_parse, parse, source, tree */
63 // Make a new object that inherits members from an existing object.
65 if (typeof Object.create !== 'function') {
66 Object.create = function (o) {
73 // Transform a token object into an exception object and throw it.
75 Object.prototype.error = function (message, t) {
77 t.name = "SyntaxError";
84 var parse = make_parse();
87 var string, tree, expr, eta;
90 // string = JSON.stringify(tree, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
91 expr = tree.handler();
92 // string = JSON.stringify(expr, ['key', 'name', 'message', 'value', 'arity', 'first', 'second', 'tag', 'variable', 'left', 'right', 'bound', 'body' ], 4);
93 // string = expr.to_string() + "\n\n~~>\n\n";
95 eta = document.getElementById('ETA').checked;
96 string = string + reduce(expr, eta, false).to_string();
98 string = JSON.stringify(e, ['name', 'message', 'from', 'to', 'key',
99 'value', 'arity', 'first', 'second', 'third', 'fourth'], 4);
101 document.getElementById('OUTPUT').innerHTML = string
102 .replace(/&/g, '&')
103 .replace(/[<]/g, '<');
106 document.getElementById('PARSE').onclick = function (e) {
107 go(document.getElementById('INPUT').value);