341 lines
6.3 KiB
CoffeeScript
341 lines
6.3 KiB
CoffeeScript
# Comprehensions
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# --------------
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# * Array Comprehensions
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# * Range Comprehensions
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# * Object Comprehensions
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# * Comprehensions with Nonstandard Step
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# TODO: refactor comprehension tests
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# Basic array comprehensions.
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nums = (n * n for n in [1, 2, 3] when n & 1)
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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 & 1)
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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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# Range comprehension gymnastics.
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eq "#{i for i in [5..1]}", '5,4,3,2,1'
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eq "#{i for i in [5..-5] by -5}", '5,0,-5'
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a = 6
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b = 0
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c = -2
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eq "#{i for i in [a..b]}", '6,5,4,3,2,1,0'
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eq "#{i for i in [a..b] by c}", '6,4,2,0'
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# Multiline array comprehension with filter.
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evens = for num in [1, 2, 3, 4, 5, 6] when not (num & 1)
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num *= -1
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num -= 2
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num * -1
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eq evens + '', '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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# all isn't reserved.
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all = 1
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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'] then do (method) ->
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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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# Index values at the end of a loop.
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i = 0
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for i in [1..3]
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-> 'func'
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break if false
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ok i is 4
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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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do (i) ->
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-> -i
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eq (func() for func in funcs).join(' '), '-1 -2 -3'
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ok i is 4
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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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do (num, i) ->
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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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# Even a convoluted one.
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funcs = []
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for i in [1..3]
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do (i) ->
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x = i * 2
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((z)->
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funcs.push -> z + ' ' + i
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)(x)
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ok (func() for func in funcs).join(', ') is '2 1, 4 2, 6 3'
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funcs = []
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results = for i in [1..3]
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do (i) ->
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z = (x * 3 for x in [1..i])
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((a, b, c) -> [a, b, c].join(' ')).apply this, z
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ok results.join(', ') is '3 , 3 6 , 3 6 9'
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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 shared scopes.
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foo = ->
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for i in [0..7]
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do (i) ->
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for j in [0..7]
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do (j) ->
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-> i + j
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eq foo()[3][4](), 7
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# Scoped loop pattern matching.
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a = [[0], [1]]
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funcs = []
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for [v] in a
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do (v) ->
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funcs.push -> v
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eq funcs[0](), 0
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eq funcs[1](), 1
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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 own key, value of whiskers)
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all = (value for 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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# Comprehensions safely redeclare parameters if they're not present in closest
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# scope.
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rule = (x) -> x
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learn = ->
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rule for rule in [1, 2, 3]
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ok learn().join(' ') is '1 2 3'
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ok rule(101) is 101
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f = -> [-> ok no, 'should cache source']
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ok yes for k of [f] = f()
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# Lenient on pure statements not trying to reach out of the closure
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val = for i in [1]
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for j in [] then break
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i
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ok val[0] is i
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# Comprehensions only wrap their last line in a closure, allowing other lines
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# to have pure expressions in them.
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func = -> for i in [1]
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break if i is 2
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j for j in [1]
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ok func()[0][0] is 1
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i = 6
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odds = while i--
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continue unless i & 1
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i
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ok odds.join(', ') is '5, 3, 1'
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# Issue #897: Ensure that plucked function variables aren't leaked.
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facets = {}
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list = ['one', 'two']
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(->
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for entity in list
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facets[entity] = -> entity
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)()
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eq typeof entity, 'undefined'
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eq facets['two'](), 'two'
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# Issue #905. Soaks as the for loop subject.
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a = {b: {c: [1, 2, 3]}}
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for d in a.b?.c
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e = d
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eq e, 3
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# Issue #948. Capturing loop variables.
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funcs = []
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list = ->
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[1, 2, 3]
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for y in list()
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do (y) ->
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z = y
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funcs.push -> "y is #{y} and z is #{z}"
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eq funcs[1](), "y is 2 and z is 2"
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# Cancel the comprehension if there's a jump inside the loop.
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result = try
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for i in [0...10]
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continue if i < 5
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i
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eq result, 10
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# Comprehensions over break.
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arrayEq (break for [1..10]), []
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# Comprehensions over continue.
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arrayEq (break for [1..10]), []
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# Comprehensions over function literals.
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a = 0
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for f in [-> a = 1]
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do (f) ->
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do f
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eq a, 1
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# Comprehensions that mention arguments.
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list = [arguments: 10]
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args = for f in list
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do (f) ->
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f.arguments
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eq args[0], 10
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test "expression conversion under explicit returns", ->
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nonce = {}
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fn = ->
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return (nonce for x in [1,2,3])
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arrayEq [nonce,nonce,nonce], fn()
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fn = ->
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return [nonce for x in [1,2,3]][0]
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arrayEq [nonce,nonce,nonce], fn()
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fn = ->
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return [(nonce for x in [1..3])][0]
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arrayEq [nonce,nonce,nonce], fn()
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