#625: Incorrect handling of types
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Reporter: hjgtuyl (at) chello (dot) nl | Owner: anonymous
Type: bug | Status: assigned
Priority: normal | Milestone:
Component: Compiler (Type checker) | Version: 6.4.1
Severity: normal | Resolution:
Keywords: | Os: Windows
Architecture: Unknown |
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Changes (by anonymous):
* status: new => assigned
* owner: => anonymous
Comment:
Both versions again, without formatting:
-------------------------------------------------
{{{
import System
floor_ev (q, r, s, t) x = (q*x + r) `div` (s*x + t)
comp (q,r,s,t) (q',r',s',t') = (q*q' + r*s', q*r' + r*t', s*q' + t*s',
s*r' + t*t')
next z = floor_ev z 3
safe z n = n == floor_ev z 4
prod z n = comp (10,-10 * n, 0, 1) z
cons z k = let den = 2*k+1 in comp z (fromIntegral k, fromIntegral
(2*den), 0, fromIntegral
den)
digit :: Int -> (Integer,Integer,Integer,Integer) -> Int -> Int -> Int ->
IO ()
digit k z 0 row col = putStrLn (take (10-col) "
"++"\t:"++show (row+col))
digit k z n row col =
if safe z y
then if col == 10
then do let row' = row + 10
putStr ("\t:"++show row'++"\n"++show y)
digit k (prod z y) (n-1) row' 1
else putStr (show y) >> digit k (prod z y) (n-1) row (col+1)
else digit (k+1) (cons z k) n row col
where y = next z
main =
do [n] <- getArgs
digit 1 (1,0,0,1) (read n) 0 0
}}}
-------------------------------------------------
When substituting "safe z y" in the function "digits" with it's
definition, we get:
-------------------------------------------------
{{{
import System
floor_ev (q, r, s, t) x = (q*x + r) `div` (s*x + t)
comp (q,r,s,t) (q',r',s',t') = (q*q' + r*s', q*r' + r*t', s*q' + t*s',
s*r' + t*t')
next z = floor_ev z 3
safe z n = n == floor_ev z 4
prod z n = comp (10,-10 * n, 0, 1) z
cons z k = let den = 2*k+1 in comp z (fromIntegral k, fromIntegral
(2*den), 0, fromIntegral
den)
digit :: Int -> (Integer,Integer,Integer,Integer) -> Int -> Int -> Int ->
IO ()
digit k z 0 row col = putStrLn (take (10-col) "
"++"\t:"++show (row+col))
digit k z n row col =
if n == floor_ev z 4 -- safe z y
then if col == 10
then do let row' = row + 10
putStr ("\t:"++show row'++"\n"++show y)
digit k (prod z y) (n-1) row' 1
else putStr (show y) >> digit k (prod z y) (n-1) row (col+1)
else digit (k+1) (cons z k) n row col
where y = next z
main =
do [n] <- getArgs
digit 1 (1,0,0,1) (read n) 0 0
}}}
-------------------------------------------------
--
Ticket URL: <http://cvs.haskell.org/trac/ghc/ticket/625>
GHC <http://www.haskell.org/ghc/>
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