144 lines
3.0 KiB
CoffeeScript
144 lines
3.0 KiB
CoffeeScript
# Basic array comprehensions.
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nums = n * n for n in [1, 2, 3] when n % 2 isnt 0
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results = n * 2 for n in nums
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ok results.join(',') is '2,18'
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# Basic object comprehensions.
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obj = {one: 1, two: 2, three: 3}
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names = prop + '!' for prop of obj
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odds = prop + '!' for prop, value of obj when value % 2 isnt 0
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ok names.join(' ') is "one! two! three!"
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ok odds.join(' ') is "one! three!"
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# Basic range comprehensions.
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nums = i * 3 for i in [1..3]
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negs = x for x in [-20..-5*2]
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negs = negs[0..2]
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result = nums.concat(negs).join(', ')
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ok result is '3, 6, 9, -20, -19, -18'
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# With range comprehensions, you can loop in steps.
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results = x for x in [0...15] by 5
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ok results.join(' ') is '0 5 10'
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results = x for x in [0..100] by 10
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ok results.join(' ') is '0 10 20 30 40 50 60 70 80 90 100'
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# And can loop downwards, with a negative step.
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results = x for x in [5..1]
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ok results.join(' ') is '5 4 3 2 1'
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ok results.join(' ') is [(10-5)..(-2+3)].join(' ')
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results = x for x in [10..1]
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ok results.join(' ') is [10..1].join(' ')
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results = x for x in [10...0] by -2
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ok results.join(' ') is [10, 8, 6, 4, 2].join(' ')
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# Multiline array comprehension with filter.
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evens = for num in [1, 2, 3, 4, 5, 6] when num % 2 is 0
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num *= -1
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num -= 2
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num * -1
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ok evens.join(', ') is '4, 6, 8'
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# The in operator still works, standalone.
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ok 2 of evens
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# Ensure that the closure wrapper preserves local variables.
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obj = {}
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for method in ['one', 'two', 'three']
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obj[method] = ->
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"I'm " + method
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ok obj.one() is "I'm one"
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ok obj.two() is "I'm two"
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ok obj.three() is "I'm three"
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# Ensure that local variables are closed over for range comprehensions.
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funcs = for i in [1..3]
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-> -i
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ok (func() for func in funcs).join(' ') is '-1 -2 -3'
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# Even when referenced in the filter.
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list = ['one', 'two', 'three']
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methods = for num, i in list when num isnt 'two' and i isnt 1
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-> num + ' ' + i
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ok methods.length is 2
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ok methods[0]() is 'one 0'
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ok methods[1]() is 'three 2'
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# Naked ranges are expanded into arrays.
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array = [0..10]
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ok(num % 2 is 0 for num in array by 2)
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# Nested comprehensions.
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multiLiner =
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for x in [3..5]
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for y in [3..5]
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[x, y]
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singleLiner =
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[x, y] for y in [3..5] for x in [3..5]
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ok multiLiner.length is singleLiner.length
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ok 5 is multiLiner[2][2][1]
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ok 5 is singleLiner[2][2][1]
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# Comprehensions within parentheses.
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result = null
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store = (obj) -> result = obj
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store (x * 2 for x in [3, 2, 1])
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ok result.join(' ') is '6 4 2'
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# Closure-wrapped comprehensions that refer to the "arguments" object.
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expr = ->
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result = item * item for item in arguments
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ok expr(2, 4, 8).join(' ') is '4 16 64'
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# Fast object comprehensions over all properties, including prototypal ones.
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class Cat
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constructor: -> @name = 'Whiskers'
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breed: 'tabby'
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hair: 'cream'
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whiskers = new Cat
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own = value for key, value of whiskers
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all = value for all key, value of whiskers
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ok own.join(' ') is 'Whiskers'
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ok all.sort().join(' ') is 'Whiskers cream tabby'
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# Optimized range comprehensions.
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exxes = 'x' for [0...10]
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ok exxes.join(' ') is 'x x x x x x x x x x'
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