#14187: Transpose hangs on infinite by finite lists -------------------------------------+------------------------------------- Reporter: utikeev | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Resolution: | Keywords: transpose Operating System: Windows | Architecture: x86_64 Type of failure: Runtime | (amd64) performance bug | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Description changed by utikeev: Old description:
I found out that this code
{{{#!hs take 5 $ map (take 3) (transpose (repeat [0..1])) }}}
isn't equivalent to this one
{{{#!hs take 5 $ map (take 3) [[0,0..], [1,1..]] }}}
The second piece of code gives expectable output of {{{[[0,0,0],[1,1,1]]}}}, while first one just hangs with outpit {{{[[0,0,0],[1,1,1],}}} also probably screwing up some descriptors after interruption with Ctrl+C (as in 8.2.1, didn't have such problem in 8.0.2. I attach the screenshot of my cmd after interruption and pressing Up and Down buttons randomly for a few times. The history seems to be broken).
In my homework I had to make a function zipN, which is actually zipWith but for more than two lists. The solution which dealt with stuck was to write my own transpose and apply {{{takeWhile (not . null)}}} to the remaining part of transposed matrix.
P.S.: {{{#!hs [[0,0..],[1,1..]] == transpose (repeat [0..1]) }}} also hangs ghci.
New description: I found out that this code {{{#!hs take 5 $ map (take 3) (transpose (repeat [0..1])) }}} isn't equivalent to this one {{{#!hs take 5 $ map (take 3) [[0,0..], [1,1..]] }}} The second piece of code gives expectable output of {{{[[0,0,0],[1,1,1]]}}}, while first one just hangs with output {{{[[0,0,0],[1,1,1],}}} also probably screwing up some descriptors after interruption with Ctrl+C (as in 8.2.1, didn't have such problem in 8.0.2. I attach the screenshot of my cmd after interruption and pressing Up and Down buttons randomly for a few times. The history seems to be broken). In my homework I had to make a function zipN, which is actually zipWith but for more than two lists. The solution which dealt with stuck was to write my own transpose and apply {{{takeWhile (not . null)}}} to the remaining part of transposed matrix. P.S.: {{{#!hs [[0,0..],[1,1..]] == transpose (repeat [0..1]) }}} also hangs ghci. -- -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14187#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler