158 lines
3.2 KiB
JavaScript
158 lines
3.2 KiB
JavaScript
// Type representations:
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//
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// number are numbers
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//
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// cons pairs are [first, rest]
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//
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// function closures are Closures
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// primitive procedures are regular functions.
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// No error trapping at the moment.
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var Primitives = {
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'display': function(argl) {
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MACHINE.params.currentDisplayer(argl[0]);
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},
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'newline': function(argl) {
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MACHINE.params.currentDisplayer("\n");
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},
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'displayln': function(argl){
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MACHINE.params.currentDisplayer(argl[0]);
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MACHINE.params.currentDisplayer("\n");
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},
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'pi' : Math.PI,
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'e' : Math.E,
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'=': function(argl) {
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return argl[0] === argl[1][0];
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},
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'<': function(argl) {
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return argl[0] < argl[1][0];
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},
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'+': function(argl) {
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return argl[0] + argl[1][0];
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},
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'*': function(argl) {
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return argl[0] * argl[1][0];
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},
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'-': function(argl) {
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return argl[0] - argl[1][0];
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},
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'/': function(argl) {
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return argl[0] / argl[1][0];
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},
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'cons': function(argl) {
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return [argl[0], argl[1][0]];
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},
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'list': function(argl) {
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return argl;
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},
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'car': function(argl) {
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return argl[0][0];
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},
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'cdr': function(argl) {
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return argl[0][1];
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},
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'null' : undefined,
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'null?': function(argl) {
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return argl[0] === undefined;
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}
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};
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// A closure consists of its free variables as well as a label
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// into its text segment.
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var Closure = function(label, arity, closedVals, displayName) {
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this.label = label;
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this.arity = arity;
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this.closedVals = closedVals;
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this.displayName = displayName;
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};
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// adaptToJs: closure -> (array (X -> void) -> void)
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// Converts closures to functions that can be called from the
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// JavaScript toplevel.
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Closure.prototype.adaptToJs = function() {
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var that = this;
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return function(args, success, fail) {
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var oldEnv = MACHINE.env;
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var oldCont = MACHINE.cont;
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var oldProc = MACHINE.proc;
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var oldArgl = MACHINE.argl;
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var oldVal = MACHINE.val;
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trampoline(
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function() {
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var proc = that;
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MACHINE.proc = proc;
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MACHINE.argl = undefined;
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for(var i = args.length - 1; i >= 0; i--) {
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MACHINE.argl = [args[i], MACHINE.argl];
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}
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MACHINE.cont = function() {
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var result = MACHINE.val;
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MACHINE.env = oldEnv;
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MACHINE.cont = oldCont;
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MACHINE.proc = oldProc;
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MACHINE.argl = oldArgl;
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MACHINE.val = oldVal;
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success(result);
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};
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proc.label();
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},
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function() {
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},
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function(e) {
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return fail(e);
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});
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}
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};
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var MACHINE={callsBeforeTrampoline: 100,
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val:undefined,
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proc:undefined,
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env: [],
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control : [],
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params: {currentDisplayer: function(v) {},
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currentErrorHandler: function(e) {}}};
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var trampoline = function(initialJump, success, fail) {
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var thunk = initialJump;
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MACHINE.callsBeforeTrampoline = 100;
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while(thunk) {
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try {
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thunk();
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break;
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} catch (e) {
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if (typeof(e) === 'function') {
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thunk = e;
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MACHINE.callsBeforeTrampoline = 100;
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} else {
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return fail(e);
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}
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}
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}
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return success();
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};
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