62 lines
1.6 KiB
JavaScript
62 lines
1.6 KiB
JavaScript
// Arity structure
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(function(baselib) {
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var exports = {};
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baselib.arity = exports;
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var ArityAtLeast = plt.baselib.structs.makeStructureType(
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'arity-at-least', false, 1, 0, false, false);
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// An arity is either a primitive number, an ArityAtLeast instance,
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// or a list of either primitive numbers or ArityAtLeast instances.
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var isArityAtLeast = ArityAtLeast.predicate;
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var arityAtLeastValue = function(x) {
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var val = ArityAtLeast.accessor(x, 0);
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return val;
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}
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ArityAtLeast.type.prototype.toString = function() {
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return '#<arity-at-least ' + arityAtLeastValue(this) + '>';
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};
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// isArityMatching: arity natural -> boolean
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// Produces true if n satisfies the arity.
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var isArityMatching = function(arity, n) {
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if (typeof(arity) === 'number') {
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return arity === n;
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} else if (isArityAtLeast(arity)) {
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return n >= arityAtLeastValue(arity);
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} else {
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while (arity !== plt.baselib.lists.EMPTY) {
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if (typeof(arity.first) === 'number') {
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if (arity.first === n) { return true; }
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} else if (isArityAtLeast(arity)) {
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if (n >= arityAtLeastValue(arity.first)) { return true; }
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}
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arity = arity.rest;
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}
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return false;
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}
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}
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//////////////////////////////////////////////////////////////////////
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exports.ArityAtLeast = ArityAtLeast;
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exports.makeArityAtLeast = ArityAtLeast.constructor;
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exports.isArityAtLeast = isArityAtLeast;
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exports.isArityMatching = isArityMatching;
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exports.arityAtLeastValue = arityAtLeastValue;
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})(this['plt'].baselib); |