Catamorphism: Difference between revisions
Content deleted Content added
→{{header|AppleScript}}: Primitive and output updated |
|||
Line 248: | Line 248: | ||
(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). |
||
<lang AppleScript> |
<lang AppleScript> |
||
---------------------- CATAMORPHISMS --------------------- |
|||
-- 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 |
||
Line 287: | Line 289: | ||
-- OTHER FUNCTIONS DEFINED IN TERMS OF FOLDL AND FOLDR |
--- OTHER FUNCTIONS DEFINED IN TERMS OF FOLDL AND FOLDR -- |
||
-- concat :: |
-- concat :: [String] -> string |
||
on concat(xs) |
on concat(xs) |
||
foldl(my append, "", xs) |
|||
⚫ | |||
⚫ | |||
⚫ | |||
end script |
|||
if length of xs > 0 and class of (item 1 of xs) is string then |
|||
⚫ | |||
else |
|||
⚫ | |||
end if |
|||
foldl(append, unit, xs) |
|||
end concat |
end concat |
||
-- product :: Num a => [a] -> a |
-- product :: Num a => [a] -> a |
||
Line 315: | Line 307: | ||
foldr(result, 1, xs) |
foldr(result, 1, xs) |
||
end product |
end product |
||
-- str :: a -> String |
|||
on str(x) |
|||
x as string |
|||
end str |
|||
-- sum :: Num a => [a] -> a |
-- sum :: Num a => [a] -> a |
||
Line 328: | Line 327: | ||
--------------------------- TEST ------------------------- |
|||
on run |
on run |
||
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} |
||
{sum(xs), product(xs), concat(xs)} |
{sum(xs), product(xs), concat(map(str, xs))} |
||
--> {55, 3628800, "10987654321"} |
--> {55, 3628800, "10987654321"} |
||
Line 338: | Line 337: | ||
--------------------- GENERIC FUNCTION ------------------- |
|||
-- append :: String -> String -> String |
|||
on append(a, b) |
|||
⚫ | |||
end append |
|||
-- map :: (a -> b) -> [a] -> [b] |
|||
on map(f, xs) |
|||
-- The list obtained by applying f |
|||
-- to each element of xs. |
|||
tell mReturn(f) |
|||
⚫ | |||
⚫ | |||
repeat with i from 1 to lng |
|||
set end of lst to |λ|(item i of xs, i, xs) |
|||
⚫ | |||
return lst |
|||
⚫ | |||
end map |
|||
-- Lift 2nd class handler function into 1st class script wrapper |
-- Lift 2nd class handler function into 1st class script wrapper |
||
Line 352: | Line 372: | ||
end mReturn</lang> |
end mReturn</lang> |
||
{{out}} |
{{out}} |
||
<pre>{55, 3628800, " |
<pre>{55, 3628800, "12345678910"}</pre> |
||
=={{header|Arturo}}== |
=={{header|Arturo}}== |