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