RosettaCodeData/Task/Mutual-recursion/AppleScript/mutual-recursion-1.applescript

67 lines
1.1 KiB
AppleScript

-- f :: Int -> Int
on f(x)
if x = 0 then
1
else
x - m(f(x - 1))
end if
end f
-- m :: Int -> Int
on m(x)
if x = 0 then
0
else
x - f(m(x - 1))
end if
end m
-- TEST
on run
set xs to range(0, 19)
{map(f, xs), map(m, xs)}
end run
-- GENERIC FUNCTIONS
-- map :: (a -> b) -> [a] -> [b]
on map(f, xs)
tell mReturn(f)
set lng to length of xs
set lst to {}
repeat with i from 1 to lng
set end of lst to lambda(item i of xs, i, xs)
end repeat
return lst
end tell
end map
-- Lift 2nd class handler function into 1st class script wrapper
-- mReturn :: Handler -> Script
on mReturn(f)
if class of f is script then
f
else
script
property lambda : f
end script
end if
end mReturn
-- range :: Int -> Int -> [Int]
on range(m, n)
if n < m then
set d to -1
else
set d to 1
end if
set lst to {}
repeat with i from m to n by d
set end of lst to i
end repeat
return lst
end range