Catamorphism: Difference between revisions
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(→{{header|AppleScript}}: Primitive and output updated) |
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(Note that to obtain first-class functions from user-defined AppleScript handlers, we have to 'lift' them into script objects). |
(Note that to obtain first-class functions from user-defined AppleScript handlers, we have to 'lift' them into script objects). |
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<lang AppleScript> |
<lang AppleScript> |
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---------------------- CATAMORPHISMS --------------------- |
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-- the arguments available to the called function f(a, x, i, l) are |
-- the arguments available to the called function f(a, x, i, l) are |
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-- OTHER FUNCTIONS DEFINED IN TERMS OF FOLDL AND FOLDR |
--- OTHER FUNCTIONS DEFINED IN TERMS OF FOLDL AND FOLDR -- |
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-- concat :: |
-- concat :: [String] -> string |
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on concat(xs) |
on concat(xs) |
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foldl(my append, "", xs) |
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| ⚫ | |||
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end script |
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if length of xs > 0 and class of (item 1 of xs) is string then |
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else |
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end if |
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foldl(append, unit, xs) |
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end concat |
end concat |
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-- product :: Num a => [a] -> a |
-- product :: Num a => [a] -> a |
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foldr(result, 1, xs) |
foldr(result, 1, xs) |
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end product |
end product |
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-- str :: a -> String |
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on str(x) |
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x as string |
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end str |
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-- sum :: Num a => [a] -> a |
-- sum :: Num a => [a] -> a |
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--------------------------- TEST ------------------------- |
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on run |
on run |
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set xs to {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} |
set xs to {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} |
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{sum(xs), product(xs), concat(xs)} |
{sum(xs), product(xs), concat(map(str, xs))} |
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--> {55, 3628800, "10987654321"} |
--> {55, 3628800, "10987654321"} |
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--------------------- GENERIC FUNCTION ------------------- |
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-- append :: String -> String -> String |
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on append(a, b) |
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end append |
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-- map :: (a -> b) -> [a] -> [b] |
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on map(f, xs) |
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-- The list obtained by applying f |
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-- to each element of xs. |
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tell mReturn(f) |
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| ⚫ | |||
repeat with i from 1 to lng |
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set end of lst to |λ|(item i of xs, i, xs) |
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return lst |
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end map |
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-- Lift 2nd class handler function into 1st class script wrapper |
-- Lift 2nd class handler function into 1st class script wrapper |
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end mReturn</lang> |
end mReturn</lang> |
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{{out}} |
{{out}} |
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<pre>{55, 3628800, " |
<pre>{55, 3628800, "12345678910"}</pre> |
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=={{header|Arturo}}== |
=={{header|Arturo}}== |
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