49 lines
1.1 KiB
Haskell
49 lines
1.1 KiB
Haskell
|
|
-- (c) MP-I (1998/9-2006/7) and CP (2005/6-2022/23)
|
|
|
|
module NEList where
|
|
|
|
import Cp
|
|
|
|
-- (1) Datatype definition -----------------------------------------------------
|
|
|
|
-- data [a] = a | (:) a ( a) deriving Show
|
|
|
|
inl = either singl (uncurry (:))
|
|
|
|
out [a] = Left a
|
|
out (a:x) = Right(a,x)
|
|
|
|
-- (2) Ana + cata + hylo -------------------------------------------------------
|
|
|
|
base g f = g -|- (g >< f)
|
|
|
|
rec f = base id f
|
|
|
|
cata g = g . rec (cata g) . out
|
|
|
|
ana g = inl . (rec (ana g) ) . g
|
|
|
|
hylo h g = cata h . ana g
|
|
|
|
|
|
-- (3) Examples ----------------------------------------------------------------
|
|
|
|
concatg ([],ys) = i1 ys
|
|
concatg (x:xs,ys) = i2([x],(xs,ys))
|
|
|
|
concath = either id f
|
|
where f([a],l) = a:l
|
|
|
|
glast = cata (either id p2)
|
|
|
|
{--
|
|
merge (l,[]) = l
|
|
merge ([],r) = r
|
|
merge (x:xs,y:ys) | x < y = x : merge(xs,y:ys)
|
|
| otherwise = y : merge(x:xs,ys)
|
|
--}
|
|
mrg (l,[]) = i1 l
|
|
mrg ([],r) = i1 r
|
|
mrg (x:xs,y:ys) | x < y = i2(x,(xs,y:ys))
|
|
| otherwise = i2(y,(x:xs,ys))
|