26 lines
713 B
Text
26 lines
713 B
Text
REBOL [
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Title: "Array Callback"
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URL: http://rosettacode.org/wiki/Apply_a_callback_to_an_Array
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]
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map: func [
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"Apply a function across an array."
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f [native! function!] "Function to apply to each element of array."
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a [block!] "Array to process."
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/local x
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][x: copy [] forall a [append x do [f a/1]] x]
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square: func [x][x * x]
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; Tests:
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assert: func [code][print [either do code [" ok"]["FAIL"] mold code]]
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print "Simple loop, modify in place:"
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assert [[1 100 81] = (a: [1 10 9] forall a [a/1: square a/1] a)]
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print [crlf "Functional style with 'map':"]
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assert [[4 16 36] = map :square [2 4 6]]
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print [crlf "Applying native function with 'map':"]
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assert [[2 4 6] = map :square-root [4 16 36]]
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