moonscript/spec/comprehension_spec.moon
2013-06-30 21:05:52 -07:00

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describe "comprehension", ->
it "should double every number", ->
input = {1,2,3,4,5,6}
output_1 = [i * 2 for _, i in pairs input ]
output_2 = [i * 2 for i in *input ]
assert.same output_1, {2,4,6,8,10,12}
it "should create a slice", ->
input = {1,2,3,4,5,6}
slice_1 = [i for i in *input[1,3]]
slice_2 = [i for i in *input[,3]]
slice_3 = [i for i in *input[3,]]
slice_4 = [i for i in *input[,]]
slice_5 = [i for i in *input[,,2]]
slice_6 = [i for i in *input[2,,2]]
assert.same slice_1, {1,2,3}
assert.same slice_1, slice_2
assert.same slice_3, {3,4,5,6}
assert.same slice_4, input
assert.same slice_5, {1,3,5}
assert.same slice_6, {2,4,6}
it "should be able to assign to self", ->
input = {1,2,3,4}
output = input
output = [i * 2 for i in *output]
assert.same input, {1,2,3,4}
assert.same output, {2,4,6,8}
output = input
output = [i * 2 for _,i in ipairs input]
assert.same input, {1,2,3,4}
assert.same output, {2,4,6,8}
describe "table comprehension", ->
it "should copy table", ->
input = { 1,2,3, hello: "world", thing: true }
output = {k,v for k,v in pairs input }
assert.is_true input != output
assert.same input, output
it "should support when", ->
input = {
color: "red"
name: "fast"
width: 123
}
output = { k,v for k,v in pairs input when k != "color" }
assert.same output, { name: "fast", width: 123 }
it "should do unpack", ->
input = {4,9,16,25}
output = {i, math.sqrt i for i in *input}
assert.same output, { [4]: 2, [9]: 3, [16]: 4, [25]: 5 }
it "should use multiple return values", ->
input = { {"hello", "world"}, {"foo", "bar"} }
output = { unpack tuple for tuple in *input }
assert.same output, { foo: "bar", hello: "world" }