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anonymous [memoized] fibonacci range, using y-combinator in JavaScript
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(function(Y, memoize){ | |
return (function(range, map, fib) { | |
return function(a, b) { | |
return map(fib, range(a, b)); | |
}; | |
})( | |
Y(function(range, a, b, inc) { | |
inc = inc || 1; | |
if(a === b) return [a]; | |
return [a].concat(range(range, a+1, b)); | |
}), | |
Y(function(map, fn, arr) { | |
if(!arr.length) return []; | |
return [fn(arr[0])].concat(map(map, fn, arr.slice(1))); | |
}), | |
Y(memoize(function(fib, num) { | |
if(num < 2) return 1; | |
return fib(fib, num-2)+fib(fib, num-1); | |
})) | |
); | |
})( | |
function(fn) { | |
return function() { | |
var args = [].slice.call(arguments); | |
return fn.apply(null, [fn].concat(args)); | |
}; | |
}, | |
function(fn) { | |
var memo = {}; | |
return function() { | |
var args = [].slice.call(arguments), | |
key = args.join(','); | |
return memo[key] || (memo[key] = fn.apply(null, args)); | |
}; | |
} | |
)(0, 100); |
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