[Haskell-cafe] Named data type members
yin
yin at atom.sk
Tue Jul 19 17:18:25 EDT 2005
Hello,
I've a data type:
data SomeData =
SomeData {
int1 :: Int,
int2 :: Int
}
class SomeClass where
infix 1 `i_`
i_ :: SomeData -> Int -> SomeData
infix 1 `_i`
_i :: SomeData -> Int -> SomeData
instance SomeClass SomeData where
(SomeData int1 int2) `i_` i = SomeData (int1 + i) int2
(SomeData int1 int2) `_i` i = SomeData int1 (int2 + i)
1. Possible optimalizations ...?
2. There are several data type members in 'SomeData' and I wish to
access them in other way then "(SomeData m1 m2 m3 m4 m5 ... m100) `a` i
= SomeData (m1 + i) m2 m3 ... m100"
3a. The 'SomeData' is something like c structure, which holds all
application data. One instanciated variable is passed in more functions
to each other:
-- SomeData is now very complex
initsomeData :: SomeData
initsomeData = do
var1 <- init...
...
SomeData 0 0 0 1 1 True False (-1) var1 var2 .......
main = do p <- initAplication
processEvents p
-- First Function
processEvents :: SomeData -> IO ()
processEvents p = do
event <- pollEvent
case event of
Event1 -> do
processEvents (SomeData v1 v2 v3 (v4*2) ... v100)
Event2 -> do
processEvents (SomeData v1 ... False ... v100)
Event2' -> do
processEvents (SomeData v1 ... True ... v100)
EventQuit -> do
return ()
NoMoreEvents -> do computeNext p
_ -> processEvents p
where (SomeData v1 v2 v3 v4 v5 ... v100) = p
-- An time based function
computeNextStep = do
timeDelta <- getTimeDelta
let
i1' = compute1 i1 i2 i3 ... i50
i2' = compute2 i1 i2 i3 ... i50
...
if (condition) then
-- need more computing
computeNextStep (SomeData u1 u2 ... u50 i1 i2 ... i50)
else do
p' <- (SomeData u1 u2 ... u50 i1 i2 ... i50)
draw p'
processEvents p'
where (SomeData u1 u2 ... u50 i1 i2 ... i50) = p
-- ux - uninteresting (State variables, like left-key-down
was last left-key related event: move left)
-- ix - interesting for computing
-- where x = 1, 2 ... 50
...
...
3b. every funtion needs only a part of the data... can I build for every
fintion a class with defined operators to manipulate with the data and then:
* pass the variable in func1 known as class A to func2, which is
infering a class B?
Thank you all...
Matej 'Yin' Gagyi
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