Substring/Top and tail: Difference between revisions
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(→{{header|Python}}: Variant - composing atomic functional expressions for slices) |
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print "socks"[:-1] # strip last character |
print "socks"[:-1] # strip last character |
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print "brooms"[1:-1] # strip both first and last characters</lang> |
print "brooms"[1:-1] # strip both first and last characters</lang> |
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Or, composing atomic functional expressions for these slices: |
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<lang python>from functools import (reduce) |
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def main(): |
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print ( |
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ap([tail, init, compose(init)(tail)])( |
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["knights"] |
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) |
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) |
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# --> ['nights', 'knight', 'night'] |
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# GENERIC ------------------------------------------------- |
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# tail :: [a] -> [a] |
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def tail(xs): |
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return xs[1:] |
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# init::[a] - > [a] |
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def init(xs): |
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return xs[:-1] |
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# ap (<*>) :: [(a -> b)] -> [a] -> [b] |
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def ap(fs): |
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return lambda xs: reduce( |
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lambda a, f: a + reduce( |
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lambda a, x: a + [f(x)], xs, [] |
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), fs, [] |
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) |
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# compose (<<<) :: (b -> c) -> (a -> b) -> a -> c |
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def compose(g): |
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return lambda f: lambda x: g(f(x)) |
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if __name__ == '__main__': |
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main()</lang> |
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{{Out}} |
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<pre>['nights', 'knight', 'night']</pre> |
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=={{header|Racket}}== |
=={{header|Racket}}== |
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