Re: [Haskell-cafe] x - String
On 10/17/09, Andrew Coppin andrewcop...@btinternet.com wrote:
Derek Elkins wrote:
See vacuum: http://hackage.haskell.org/package/vacuum
Could be useful... Thanks!
As Derek mentioned, vacuum would be perfect for this:
-
import Data.Word
import GHC.Vacuum
import GHC.Vacuum.ClosureType
import qualified Data.IntMap as IM
type Info = (ClosureType -- what kind of heap node is this?
,[String] -- [pkg,mod,con] for constructors
,[Int]-- pointers refering to other nodes in IntMap
,[Word]) -- literal data in constructors
overview :: HNode - Info
overview o =
let ptrs = nodePtrs o
lits = nodeLits o
itab = nodeInfo o
ctyp = itabType itab
-- only available
-- for constructors
(pkg,mod,con) = itabName itab
names = filter (not . null)
[pkg,mod,con]
in (ctyp
,names -- [] for non-data
,ptrs
,lits)
-- returns an adjacency-list graph
info :: a - [(Int,Info)]
info = fmap (\(a,b)-(a,overview b))
. IM.toList . vacuum
-- returns an adjacency-list graph
infoLazy :: a - [(Int,Info)]
infoLazy = fmap (\(a,b)-(a,overview b))
. IM.toList . vacuumLazy
-
-- example usage
data A a = A Int | B a | forall b. C b [A a]
val0 = [A 42, B (Left Nothing), C (pi,()) val0]
val1 = fmap (\n - C n []) [0..]
{-
ghci mapM_ print (info val0)
Loading package vacuum-1.0.0 ... linking ... done.
(0,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[1,2],[]))
(1,(CONSTR,[main,Main,A],[3],[]))
(2,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[4,5],[]))
(3,(CONSTR_0_1,[ghc-prim,GHC.Types,I#],[],[42]))
(4,(CONSTR,[main,Main,B],[6],[]))
(5,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[8,9],[]))
(6,(CONSTR_1_0,[base,Data.Either,Left],[7],[]))
(7,(CONSTR_NOCAF_STATIC,[base,Data.Maybe,Nothing],[],[]))
(8,(CONSTR,[main,Main,C],[10,0],[]))
(9,(CONSTR_NOCAF_STATIC,[ghc-prim,GHC.Types,[]],[],[]))
(10,(CONSTR_2_0,[ghc-prim,GHC.Tuple,(,)],[11,12],[]))
(11,(CONSTR_NOCAF_STATIC,[ghc-prim,GHC.Types,D#],[],[4614256656552045848]))
(12,(CONSTR_NOCAF_STATIC,[ghc-prim,GHC.Unit,()],[],[]))
ghci mapM_ print (infoLazy val1)
(0,(AP,[],[],[]))
ghci val1 `seq` ()
()
ghci mapM_ print (infoLazy val1)
(0,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[1,2],[]))
(1,(THUNK_2_0,[],[],[]))
(2,(THUNK_2_0,[],[],[]))
ghci length . take 2 $ val1
2
ghci mapM_ print (infoLazy val1)
(0,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[1,2],[]))
(1,(THUNK_2_0,[],[],[]))
(2,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[3,4],[]))
(3,(THUNK_2_0,[],[],[]))
(4,(THUNK_2_0,[],[],[]))
ghci case val1 of a:b:_ - a `seq` b `seq` ()
()
ghci mapM_ print (infoLazy val1)
(0,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[1,2],[]))
(1,(CONSTR,[main,Main,C],[3,4],[]))
(2,(CONSTR_2_0,[ghc-prim,GHC.Types,:],[5,6],[]))
(3,(CONSTR_0_1,[integer,GHC.Integer.Internals,S#],[],[0]))
(4,(CONSTR_NOCAF_STATIC,[ghc-prim,GHC.Types,[]],[],[]))
(5,(CONSTR,[main,Main,C],[7,4],[]))
(6,(THUNK_2_0,[],[],[]))
(7,(CONSTR_0_1,[integer,GHC.Integer.Internals,S#],[],[1]))
-}
-
Matt
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Re: [Haskell-cafe] x - String
Derek Elkins wrote: See vacuum: http://hackage.haskell.org/package/vacuum Could be useful... Thanks! ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
On Fri, Oct 16, 2009 at 8:19 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Is there any way that you can turn an arbitrary Haskell value into a string? I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? Ghci only displays values with a Show instance. ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
David Virebayre wrote: On Fri, Oct 16, 2009 at 8:19 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Is there any way that you can turn an arbitrary Haskell value into a string? I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? Ghci only displays values with a Show instance. Well, I can live with getting an empty string if no Show instance is available. But I can't figure out how to even do that... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
GHCi can't show you functions can it? Unless you have a Show instance for functions loaded. I think the basic answer is no, not even with crazy unsafe stuff, because without the typeclass constraint GHC doesn't know to pass around the secret dictionary containing the methods that tell it how to show your data. On Fri, Oct 16, 2009 at 2:19 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Is there any way that you can turn an arbitrary Haskell value into a string? I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? Basically, I'm writing a mutable container implementation. It can hold any type of data, but it would massively aid debugging if I could actually print out what's in it. On the other hand, I don't want to alter the entire program to have Show constraints everywhere just so I can print out some debug traces (and then alter everything back again afterwards once I'm done debugging). Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
Andrew Coppin wrote: Is there any way that you can turn an arbitrary Haskell value into a string? No, the only values of type a - String are the constant functions and _|_. I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? No. GHCi does not always do this: Prelude Data.Ratio let plus1 = (+1) Prelude Data.Ratio plus1 interactive:1:0: No instance for (Show (a - a)) arising from a use of `print' at interactive:1:0-4 Possible fix: add an instance declaration for (Show (a - a)) In a stmt of a 'do' expression: print it Prelude Data.Ratio Basically, I'm writing a mutable container implementation. It can hold any type of data, but it would massively aid debugging if I could actually print out what's in it. On the other hand, I don't want to alter the entire program to have Show constraints everywhere just so I can print out some debug traces (and then alter everything back again afterwards once I'm done debugging). This is not advisable, as you see. Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) What is the problem with adding a function showMyContainer :: (Show a) = Container a - String ? In this case you can show your container (for debugging purposes), but only if you have Showable elements in your container. Cheers, Jochem -- Jochem Berndsen | joc...@functor.nl | joc...@牛在田里.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
Hello Andrew, Friday, October 16, 2009, 10:19:46 PM, you wrote: actually print out what's in it. On the other hand, I don't want to alter the entire program to have Show constraints everywhere just so I can print out some debug traces (and then alter everything back again afterwards once I'm done debugging). i personally just never use explicit function type declarations. this way constraints are added and removed automatically depending on functions you are using inside -- Best regards, Bulatmailto:bulat.zigans...@gmail.com ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
Jochem Berndsen wrote: I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? No. GHCi does not always do this: Prelude Data.Ratio let plus1 = (+1) Prelude Data.Ratio plus1 interactive:1:0: No instance for (Show (a - a)) arising from a use of `print' at interactive:1:0-4 Possible fix: add an instance declaration for (Show (a - a)) In a stmt of a 'do' expression: print it Prelude Data.Ratio The GHCi *debugger* can print out even values for which no Show instance exists. (But yes, it fails to print anything interesting for function types... It works for ADTs that don't have Show though.) Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) What is the problem with adding a function showMyContainer :: (Show a) = Container a - String ? In this case you can show your container (for debugging purposes), but only if you have Showable elements in your container. This could plausibly work... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
Andrew has mentioned the debugger several times, NOT the interactive REPL. That is, using :-commands to inspect values. -Ross On Oct 16, 2009, at 2:46 PM, Daniel Peebles wrote: My GHCi can't do that :o I just wrote data A = B | C and loaded the file into GHCi. Typing B gives me: interactive:1:0: No instance for (Show A) arising from a use of `print' at interactive:1:0 Possible fix: add an instance declaration for (Show A) In a stmt of a 'do' expression: print it The error also gives an idea of what GHCi is doing behind the scenes: it's just calling print, which has a Show constraint. On Fri, Oct 16, 2009 at 2:40 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Jochem Berndsen wrote: I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? No. GHCi does not always do this: Prelude Data.Ratio let plus1 = (+1) Prelude Data.Ratio plus1 interactive:1:0: No instance for (Show (a - a)) arising from a use of `print' at interactive:1:0-4 Possible fix: add an instance declaration for (Show (a - a)) In a stmt of a 'do' expression: print it Prelude Data.Ratio The GHCi *debugger* can print out even values for which no Show instance exists. (But yes, it fails to print anything interesting for function types... It works for ADTs that don't have Show though.) Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) What is the problem with adding a function showMyContainer :: (Show a) = Container a - String ? In this case you can show your container (for debugging purposes), but only if you have Showable elements in your container. This could plausibly work... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
Whoops, sorry about that then! On Fri, Oct 16, 2009 at 2:59 PM, Ross Mellgren rmm-hask...@z.odi.ac wrote: Andrew has mentioned the debugger several times, NOT the interactive REPL. That is, using :-commands to inspect values. -Ross On Oct 16, 2009, at 2:46 PM, Daniel Peebles wrote: My GHCi can't do that :o I just wrote data A = B | C and loaded the file into GHCi. Typing B gives me: interactive:1:0: No instance for (Show A) arising from a use of `print' at interactive:1:0 Possible fix: add an instance declaration for (Show A) In a stmt of a 'do' expression: print it The error also gives an idea of what GHCi is doing behind the scenes: it's just calling print, which has a Show constraint. On Fri, Oct 16, 2009 at 2:40 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Jochem Berndsen wrote: I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? No. GHCi does not always do this: Prelude Data.Ratio let plus1 = (+1) Prelude Data.Ratio plus1 interactive:1:0: No instance for (Show (a - a)) arising from a use of `print' at interactive:1:0-4 Possible fix: add an instance declaration for (Show (a - a)) In a stmt of a 'do' expression: print it Prelude Data.Ratio The GHCi *debugger* can print out even values for which no Show instance exists. (But yes, it fails to print anything interesting for function types... It works for ADTs that don't have Show though.) Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) What is the problem with adding a function showMyContainer :: (Show a) = Container a - String ? In this case you can show your container (for debugging purposes), but only if you have Showable elements in your container. This could plausibly work... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
No problem, just trying to make sure the conversation stays on track :-) -Ross On Oct 16, 2009, at 3:26 PM, Daniel Peebles wrote: Whoops, sorry about that then! On Fri, Oct 16, 2009 at 2:59 PM, Ross Mellgren rmm- hask...@z.odi.ac wrote: Andrew has mentioned the debugger several times, NOT the interactive REPL. That is, using :-commands to inspect values. -Ross On Oct 16, 2009, at 2:46 PM, Daniel Peebles wrote: My GHCi can't do that :o I just wrote data A = B | C and loaded the file into GHCi. Typing B gives me: interactive:1:0: No instance for (Show A) arising from a use of `print' at interactive:1:0 Possible fix: add an instance declaration for (Show A) In a stmt of a 'do' expression: print it The error also gives an idea of what GHCi is doing behind the scenes: it's just calling print, which has a Show constraint. On Fri, Oct 16, 2009 at 2:40 PM, Andrew Coppin andrewcop...@btinternet.com wrote: Jochem Berndsen wrote: I rephrase: There *is* a way to turn arbitrary values into strings. I know there is, because the GHCi debugger *does* it. The question is, does anybody know of an /easy/ way to do this? No. GHCi does not always do this: Prelude Data.Ratio let plus1 = (+1) Prelude Data.Ratio plus1 interactive:1:0: No instance for (Show (a - a)) arising from a use of `print' at interactive:1:0-4 Possible fix: add an instance declaration for (Show (a - a)) In a stmt of a 'do' expression: print it Prelude Data.Ratio The GHCi *debugger* can print out even values for which no Show instance exists. (But yes, it fails to print anything interesting for function types... It works for ADTs that don't have Show though.) Anybody know of a way to do this? (As it happens, the values I'm testing with are all Showable anyway, but the type checker doesn't know that...) What is the problem with adding a function showMyContainer :: (Show a) = Container a - String ? In this case you can show your container (for debugging purposes), but only if you have Showable elements in your container. This could plausibly work... ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
Re: [Haskell-cafe] x - String
See vacuum: http://hackage.haskell.org/package/vacuum ___ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
