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module serialize2start
/*
Definition for assignment 2 in AFP 2017
Pieter Koopman pieter@cs.ru.nl
September 2017
*/
import StdEnv, StdMaybe
class serialize a where
write :: a [String] -> [String]
read :: [String] -> Maybe (a,[String])
instance serialize Bool where
write b c = [toString b:c]
read ["True":r] = Just (True,r)
read ["False":r] = Just (False,r)
read _ = Nothing
instance serialize Int where
write i c = [toString i:c]
read [s:r]
# i = toInt s
| s == toString i
= Just (i,r)
= Nothing
read _ = Nothing
// ---
:: UNIT = UNIT
:: EITHER a b = LEFT a | RIGHT b
:: PAIR a b = PAIR a b
:: CONS a = CONS String a
// ---
:: ListG a :== EITHER (CONS UNIT) (CONS (PAIR a [a]))
instance serialize [a] | serialize a where // to be imporved
write l c = c
read l = Nothing
:: Bin a = Leaf | Bin (Bin a) a (Bin a)
:: BinG a :== EITHER (CONS UNIT) (CONS (PAIR (Bin a) (PAIR a (Bin a))))
instance serialize (Bin a) | serialize a where // to be imporved
write a c = c
read l = Nothing
instance == (Bin a) | == a where // better use the generic approach
(==) Leaf Leaf = True
(==) (Bin l a r) (Bin k b s) = l == k && a == b && r == s
(==) _ _ = False
// ---
Start =
[test True
,test False
,test 0
,test 123
,test -36
,test [42]
,test [0..4]
,test [[True],[]]
,test (Bin Leaf True Leaf)
,test [Bin (Bin Leaf [1] Leaf) [2] (Bin Leaf [3] (Bin Leaf [4,5] Leaf))]
,test [Bin (Bin Leaf [1] Leaf) [2] (Bin Leaf [3] (Bin (Bin Leaf [4,5] Leaf) [6,7] (Bin Leaf [8,9] Leaf)))]
]
test :: a -> ([String],[String]) | serialize, == a
test a =
(if (isJust r)
(if (fst jr == a)
(if (isEmpty (tl (snd jr)))
["Oke "]
["Fail: not all input is consumed! ":snd jr])
["Fail: Wrong result ":write (fst jr) []])
["Fail: read result is Nothing "]
, ["write produces ": s]
)
where
s = write a ["\n"]
r = read s
jr = fromJust r
|
