Function composition: Difference between revisions
m
→{{header|AppleScript}}: Tidied
m (→{{header|AppleScript}}: Tidied) |
|||
Line 220:
We can generalise this lifting with an '''mReturn''' or '''mInject''' function, which injects a handler into a script for us. This allows use to write higher-order composition and pipelining functions which take a pair (or sequence of) ordinary handlers as arguments, and return a first class script object. (We can also use mReturn to equip AppleScript with '''map''' and '''fold''' functions which take a list and an ordinary handler as arguments).
<lang applescript>
-- compose :: [(a -> a)] -> (a -> a)▼
on compose(fs)▼
script▼
on |λ|(x)▼
script▼
on |λ|(a, f)▼
mReturn(f)'s |λ|(a)▼
end |λ|▼
end script▼
foldr(result, x, fs)▼
end |λ|▼
end script▼
end compose▼
on root(x)
x ^ 0.5
Line 234 ⟶ 251:
end half
▲-- TEST -----------------------------------------------------------------------
on run
Line 242 ⟶ 258:
end run
-------------------- GENERIC FUNCTIONS -------------------
▲-- compose :: [(a -> a)] -> (a -> a)
▲on compose(fs)
▲ script
▲ on |λ|(x)
▲ script
▲ on |λ|(a, f)
▲ mReturn(f)'s |λ|(a)
▲ end |λ|
▲ end script
▲ foldr(result, x, fs)
▲ end |λ|
▲ end script
▲end compose
-- foldr :: (a -> b -> a) -> a -> [b] -> a
| |||