Anonymous recursion: Difference between revisions
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(→{{header|Perl 6}}: mention how the sequence operator "checks for negative") |
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<lang haskell>ghci> map fib [-4..10] |
<lang haskell>ghci> map fib [-4..10] |
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[Nothing,Nothing,Nothing,Nothing,Just 1,Just 1,Just 2,Just 3,Just 5,Just 8,Just 13,Just 21,Just 34,Just 55,Just 89]</lang> |
[Nothing,Nothing,Nothing,Nothing,Just 1,Just 1,Just 2,Just 3,Just 5,Just 8,Just 13,Just 21,Just 34,Just 55,Just 89]</lang> |
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=={{header|Icon}} and {{header|Unicon}}== |
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The following solution works in both languages. The a cache is used |
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to improve performance. |
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<lang unicon>procedure main(A) |
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every write("fib(",a := numeric(!A),")=",fib(a)) |
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end |
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procedure fib(n) |
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local source, i |
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static cache |
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initial { |
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cache := table() |
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cache[0] := 0 |
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cache[1] := 1 |
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} |
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if type(n) == "integer" & n >= 0 then |
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return n @ makeProc {{ |
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i := @(source := &source) |
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if /cache[i] then cache[i] := ((i-1)@makeProc(^¤t) + |
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(i-2)@makeProc(^¤t)) |
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cache[i] @ source |
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}} |
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end |
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procedure makeProc(A) |
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A := if type(A) == "list" then A[1] |
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return (@A, A) # prime and return |
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end</lang> |
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=={{header|J}}== |
=={{header|J}}== |
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