- Hat - Haskell.org

spend a lot of time with alex generated module
by kgu 17 Aug '06

17 Aug '06

hat-trans spends a lot of time (really a lot of time) in generate module from a module generated by alex. The original module has 330 lines of code and module generated by hat-trans has 40700 !!. Somebody knows what's happening? thanks -- View this message in context: http://www.nabble.com/spend-a-lot-of-time-with-alex-generated-module-tf2081… Sent from the Haskell - Hat forum at Nabble.com.

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problems with debian
by inormann 10 Aug '06

10 Aug '06

Hi, installation of hat on my debian Linux fails returning the message: hat-ghc6: Depends: ghc6 (< 6.2.2+) but 6.4.1-1 is installed and it is kept back. Is there a newer deb-package around that supports ghc-6.4.1? Alternatively I have just managed to compile hat from the tar-file and started the little tutorial at http://www.haskell.org/hat/tutorial1.html my session with the error report: hat-trans Insort.hs hat-trans is not installed/configured for debian. (Tried directory /usr/local/share/lib/hat) See your system administrator, or install it yourself from http://www.haskell.org/hat/ Now I am really in a dead end :-( replacing ghc-6.4.1 by ghc- 6.2.2 is not really what I want. Any suggestions what to do? Immanuel -- View this message in context: http://www.nabble.com/problems-with-debian-tf1924566.html#a5269742 Sent from the Haskell - Hat forum at Nabble.com.

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GUI for Hat
by Peter Nuttall 29 Jul '06

29 Jul '06

Hello all, I'm doing my dissertation on writing a GUI for hat, and Neil Mitchell suggested I send a mail saying what i was planning to see if you guys had any good ideas or comments. This is the proposal: The problem Hat provides a easy way to generate a trace, and various tools have been developed to examine the traces produced by it. However, these tools have two main flaws: They are hard to learn and use and they are not linked together. Ideally we would like hat to be as easy to use as possible. This way it can both be used to debug real programs by Haskell programmers, but can be used as a teaching tool for beginners, so they can see how lazy evaluation works and find simple bugs when they write their first programs. The solution Write a graphical user interface to Hat. A clickable GUI will be easier to use than a ncurses GUI, and will seem easier to use. The GUI will provide the same functionality as the hat tools do already, but it will be easier to use. This will be done by separating out the current user interface from the functionality as much as possible, then making the functionality into a library. As part of this, I will try and upgrade the tools to use the new tracing library written by Tom Shackell. The GUI's will be implemented in GTK2HS . It will consist of a Window with tabs for each tool. Neil Mitchell has already constructed a GUI, and I plan to use this as a starting point. The tools that will be usable though the GUI will be: Search This will let the user search though all the functions called, and see that function.s inputs and output. The UI will be based on that of JuK, with searching using haskell.s pattern matching syntax. Monad A step over debugger for do blocks. This will be similar to normal debuggers Stack. When loading a a trace that has terminated with an error, the GUI will show a listing of the last functions called and their inputs and outputs. It will collapse any loops. Cover It will use hs-colour to try and show which functions are being used for a set of inputs. If the new tracing library is used, and it supports taking the union of traces, this will be used to show coverage from lots of traces. This can be tied into quickcheck. Ethereal bit. Ethereal is a tool for examining network traffic, and my plan is to . borrow from it's "follow TCP stream" feature, which shows you all the traffic in a stream, and lets you see messages and replies. It will show text moving in and out of handles, and display the logical time between messages. Display bit. This will allow the user to see how redexes happen and allow the use to see laziness in action. This will be based on hat-amin. It is dependent on writing a good graph drawing function. algorithmic This will be a normal algorithmic debugger, though I haven.t thought of how it will work in a GUI. Any suggestions, comments? Pete

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Hat-Gui, new tool
by Neil Mitchell 08 Jul '06

08 Jul '06

Hi, I have started writing Hat-Gui, a screenshot is available at: http://www-users.cs.york.ac.uk/~ndm/projects/hat-gui.png It is written with Gtk2Hs, and should be cross platform. This screenshot is slightly misleading, only hat-stack works, the other two tabs are just dummy's. However, hat-stack works perfectly, and you can open a hat file, or associate them in your Windows environment. In order to get hat-stack working I copied the HatStack.hs program, renamed it to HatStackLib.hs and tweaked it a bit. Obviously this is not the best way to do it. In order to get hat-gui working properly it would be best to split every hat tool into a module which exports a Haskell API interface (i.e. HatTools.Stack) and a command line program that imports that as hat-stack. What is the best way to acheive this split, and how should it be organised? Most of the tools are already relatively abstract - although will probably need tweaks. Thanks Neil

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Pattern match errors in do?
by Neil Mitchell 06 Jul '06

06 Jul '06

Hi With the following program: --------------------------------- import System main = do (x:_) <- getArgs print $ fact (read x) fact :: Int -> Int fact 0 = 1 fact n | n > 0 = n * fact (n - 1) -------------------------------- Running Main without any arguments via Hat gives me a trace, and the error message: > Error: pattern-match failure in do expression Running hat-stack Main.hat gives me: > Tracefile "Main.hat" contains no reference to a program error. How come? I get the same results on both Windows and Linux. Thanks Neil

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Hat for Windows
by Neil Mitchell 06 Jul '06

06 Jul '06

Hi, A preview of Hat for Windows is available at: http://www.cs.york.ac.uk/fp/temp/hat-win32-05_jul_2006.zip All hat utilities are available and seem to work apart from: hat-explore - advanced escape codes, looks pretty hard to get round hat-anim - escape codes, might be able to work round hat-detect - tries to spawn an xterm In addition, there is also hat-make, which is windows only hmake -hat alternative. Instructions for installing ================= Extract the contents of the .zip file into a folder preserving directory structure. Add the folder containing hat-make to your %PATH% variable, this is 100% required, even if you give the explicit path to hat-make when you use it. Make sure ghc is available on your system and has been added to the %PATH%. Instructions for use ============== cd to the directory containing your Haskell source hat-make Main.hs main <arguments> hat-stack Main.hat hat-observe Main.hat etc. I have tested the programs, and they all work quite well - I have not run into any limitations beyond those which happen on Hat on Linux as well. Thanks Neil

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Missing functions
by Neil Mitchell 30 Jun '06

30 Jun '06

Hi, Now I have Hat on Windows working pretty much, I have tried compiling various programs, unfortunately only very simple examples go through because of missing libraries. I have started a page on the wiki to track the missing dependancies: http://haskell.org/haskellwiki/Hat Thanks Neil

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Hat on Windows, patches
by Neil Mitchell 28 Jun '06

28 Jun '06

Hi, Attached is a patch and some files required to build Hat on Windows. These superceed the ones I sent earlier. With this you get the following tools: hat-trans, exactly as per Linux hat-make, a new tool for windows, think hmake -hat but for Windows (and not as clever) hat-check, exactly as per Linux hat-cover, not very useful unless you do -hion and -hioff since the escape codes are turned off hat-stack, like Linux minus the syntax hilighting hat-observe, lots of escape code garbage, but you can still see the answers The tweaks are: ntohl, not on Windows fopen needs a "b" in the list of options no escape codes, try and eliminate them where possible The new files are: Makefile.bat, the root of the hat repo, serves as a Makefile on Windows - please rename Makefile.bad to .bat, because Gmail won't let me send a "dangerous executable" ntohl.h, for include ntohl.c, for src\hattools, provides the implementation of ntohl HatMake.hs, for src\hattools, the implementation of hat-make Most of the user visible changes are because of the lack of escape codes, which are used in the Linux versions to make a GUI out of the console. The Windows solution would just be to use the standard GUI, and turn the tools into slightly more abstract versions which can have the two interaction methods layered on top of them. I also want to change hat-cover to have an option to output HTML, possible combined with HsColour (modified to be a Haskell library as well as a program) so you can get syntax coloured and nicely highlighted Haskell code. Thanks Neil

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Hat and Windows
by Neil Mitchell 27 Jun '06

27 Jun '06

Hi, I've tried to get Hat compiling on Windows today, and have had some success. I found the following problems and fixes: 1) hat-trans cannot be compiled with ghc -cpp (it breaks on the string gaps), and cpphs can't be used as pgmP as it is. I have submitted a patch for cpphs to make this possible. With this change, hat-trans builds fine for Windows. 2) When running hat-trans, its remarkably painful on Windows, and I got frequent unexplained crashes, but there are a few patches required: Windows does not have ntohl, so I added a specific one for Windows. SIGQUIT does not exist on Windows, I just commented out this line. fopen(file,"w") should be fopen(file,"wb") to use Binary mode under Windows. With these patches, the remaining issues are build issues - I am intending to write a very hacky hat-make which sorts these out, possibly in a Windows specific way, to make it a single hat-make Main command to generate a hat binary. I did not build the hat translated libraries under Windows, I took the Linux versions. With these changes I am able to generate a simple hat file that can be processed by the Linux hat tools properly. Thanks Neil

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Thoughts, Int vs Integer
by Neil Mitchell 26 Jun '06

26 Jun '06

Hi, Often when compiling with Hat I run into the Int vs Integer issue, in fact this is pretty much the biggest problem I have getting hat traces generated. I was considering if there was any possible change that could be performed by Hat to remove this restriction. The best I came up with makes semantic changes to the program, but these changes are "very minimal" at a guess :) The idea basically revolves around "type Int = Integer" - replace all occurances of Int with Integer at the type level, make all functions that operate on Int now operate on Integer instead, and all numeric literals can now become Integer, since there is no Int. There are two semantic changes from this which I have thought of: 1) big_number * 2 will never overflow, which will give a different semantics. Personally this sounds like a good idea, and having a hat-overflow tool to detect when an Integer goes above 2^31 would probably be a useful addition. I don't consider this change to be all that bad, since its compatible with the Haskell98 report (I think). 2) More seriously, type classes will lead to different code being invoked. For example while 0 == 0 might have invoked Int equality now it will invoke Integer equality. My guess is that if there is a program where the type class for Int is not a subset of the behaviour of that for Integer, its very weird and confusing and probably buggy. The changes to the generator that would need to be made are (as far as I can tell) as follows: * Replace all occurances of Int with Integer * Make all numeric literals 0 :: Integer * On encountering a typeclass if there existing an instance for one of Int or Integer, then use that one. If instances exists for both Int and Integer then throw away the Int version. For a prototype, allow-undecideable-instances & allow-overlapping-instances should handle this automatically. * Any primitive operations that are performed on Int and not Integer would need to be worked around, probably on a case by case basis, but this should be a small number. Comments or thoughts? Thanks Neil

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