181 lines
3.8 KiB
AppleScript
181 lines
3.8 KiB
AppleScript
------------------ LONGEST COMMON SUBSTRING ----------------
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-- longestCommon :: Eq a => [a] -> [a] -> [a]
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on longestCommon(a, b)
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-- The longest common substring of two given strings.
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script substrings
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on |λ|(s)
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map(my concat, concatMap(my tails, rest of inits(s)))
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end |λ|
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end script
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set {xs, ys} to map(substrings, {a, b})
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maximumBy(comparing(my |length|), intersect(xs, ys))
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end longestCommon
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-------------------------- TEST ---------------------------
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on run
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longestCommon("testing123testing", "thisisatest")
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end run
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-------------------- GENERIC FUNCTIONS --------------------
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-- comparing :: (a -> b) -> (a -> a -> Ordering)
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on comparing(f)
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script
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on |λ|(a, b)
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tell mReturn(f)
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set fa to |λ|(a)
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set fb to |λ|(b)
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if fa < fb then
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-1
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else if fa > fb then
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1
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else
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0
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end if
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end tell
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end |λ|
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end script
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end comparing
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-- concat :: [String] -> String
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on concat(xs)
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script go
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on |λ|(a, x)
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a & x
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end |λ|
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end script
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foldl(go, "", xs)
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end concat
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-- concatMap :: (a -> [b]) -> [a] -> [b]
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on concatMap(f, xs)
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set lng to length of xs
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set acc to {}
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tell mReturn(f)
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repeat with i from 1 to lng
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set acc to acc & (|λ|(item i of xs, i, xs))
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end repeat
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end tell
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return acc
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end concatMap
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-- foldl :: (a -> b -> a) -> a -> [b] -> a
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on foldl(f, startValue, xs)
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tell mReturn(f)
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set v to startValue
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set lng to length of xs
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repeat with i from 1 to lng
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set v to |λ|(v, item i of xs, i, xs)
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end repeat
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return v
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end tell
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end foldl
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-- inits :: String -> [String]
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on inits(xs)
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script charInit
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on |λ|(_, i, xs)
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text 1 thru i of xs
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end |λ|
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end script
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{""} & map(charInit, xs)
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end inits
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-- intersect :: (Eq a) => [a] -> [a] -> [a]
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on intersect(xs, ys)
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if length of xs < length of ys then
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set {shorter, longer} to {xs, ys}
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else
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set {longer, shorter} to {xs, ys}
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end if
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if shorter ≠ {} then
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set lst to {}
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repeat with x in shorter
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if longer contains x then set end of lst to contents of x
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end repeat
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lst
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else
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{}
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end if
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end intersect
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-- length :: [a] -> Int
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on |length|(xs)
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set c to class of xs
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if list is c or string is c then
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length of xs
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else
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(2 ^ 29 - 1) -- (maxInt - simple proxy for non-finite)
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end if
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end |length|
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-- maximumBy :: (a -> a -> Ordering) -> [a] -> a
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on maximumBy(f, xs)
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set cmp to mReturn(f)
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script max
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on |λ|(a, b)
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if a is missing value or cmp's |λ|(a, b) < 0 then
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b
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else
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a
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end if
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end |λ|
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end script
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foldl(max, missing value, xs)
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end maximumBy
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-- mReturn :: First-class m => (a -> b) -> m (a -> b)
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on mReturn(f)
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-- 2nd class handler function lifted into 1st class script wrapper.
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if script is class of f then
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f
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else
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script
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property |λ| : f
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end script
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end if
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end mReturn
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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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set lng to length of xs
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set lst to {}
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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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end repeat
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return lst
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end tell
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end map
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-- tails :: String -> [String]
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on tails(xs)
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set es to characters of xs
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script residue
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on |λ|(_, i)
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items i thru -1 of es
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end |λ|
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end script
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map(residue, es) & {""}
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end tails
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