- jhc - Haskell.org

Re: Ids in Jhc.
by John Meacham 15 Feb '08

15 Feb '08

(I'm gonna forward this response to the jhc list too, if that's okay) On Thu, Feb 14, 2008 at 12:26:49AM +0100, Lemmih wrote: > I've been wondering about your use of Ids in Jhc. > As far as I can see, the rules for Ids goes as following: > * named ids are odd > * unnamed ids are even > * id '0' has special significance. > > Can you tell me a bit about how unnamed ids are used, why id '0' has > special meaning, and how you generate new, unique unnamed ids. Yes. that is correct. named and unnamed ids behave the same way, except named ids get a pretty name when printed out as opposed to just a numebr and are generally derived from a user supplied name. Also, all 'top level' names are always 'named' to ensure they remain globally unique. named Ids are odd, these are looked up in a table that is implemented via a hash table written in c in the StringTable/ directory. due to an intentional quirk of its implementation, it only generates odd, positive values. Conversion between a number and its string form is constant time in both directions. zero is a 'special' id in that it can be treated normally except it can never appear in an expression, only in a binder. so \ v0 -> ... is okay, but \ x -> .. v0 ... is not. This means you can always use 0 as a binder when you know a value is not used without worrying about shadowing a real definition. unnamed ids are arbitrary positive even numbers, there is no particular need to allocate them in a special way, they are _not_ globally unique so you just need to ensure you don't shadow any existing variables when assigning new ones. in general, this consists of having a set of 'in scope' names (which is often something you need to keep track of anyway) and you choose some value that is not in the 'in scope' set and add it to the set. this ensures ids don't shadow each other, but not that they are unique. negative ids are used inside of a few specialized routines internally and should never make it out into the world. for instance, in the unification algorithm they are used to represent alpha-renamed values so we don't need to scan for used names before hand, however the terms returned have their original ids restored. hope this helps... It is quite bothersome to me that 'Id' is just an Int and not a newtype... that is something I have been slowing getting the code ready to fix for a while now.. John -- John Meacham - ⑆repetae.net⑆john⑈

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Darcs patch.
by Lemmih 14 Feb '08

14 Feb '08

The latests broke the makefile rule for jhcp. -- Cheers, Lemmih

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PatternGuards
by Isaac Dupree 03 Jan '08

03 Jan '08

Does Jhc currently support pattern-guards, or is one of us going to have to implement that? And does Jhc support LANGUAGE pragmas (or just as good for me, ignore them and use all its extensions all the time)? you know, for my crazy idea of compiling ghc 6.9 sometime soon :-) ~Isaac

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parse error FrontEnd/Representation.hs
by Ganesh Narayan 08 Oct '07

08 Oct '07

Hi, I pulled jhc sources (jhc, doc, haskell98, QuickCheck) from darcs and tried building jhc. But the build exits with the following error: jhc$ make ghc -O -ignore-package lang -pgmF drift-ghc -F -W -fno-warn-unused-matches -i. -iFrontEnd -package mtl -package unix -package QuickCheck -fwarn-type-defaults -fallow-undecidable-instances -fglasgow-exts -fallow-overlapping-instances --make Main.hs -o jhc --snip-- . . . --snip-- /home/haskell/DrIFT/bin/DrIFT DerivingDrift/StandardRules.hs -o /tmp/ghc12711_0/ghc12711_151.hspp /home/haskell/DrIFT/bin/DrIFT E/LambdaLift.hs -o /tmp/ghc12711_0/ghc12711_159.hspp [ 60 of 162] Compiling Info.Binary[boot] ( Info/Binary.hs-boot, nothing ) [ 95 of 162] Compiling DataConstructors[boot] ( DataConstructors.hs-boot, nothing ) [110 of 162] Compiling Representation ( FrontEnd/Representation.hs, FrontEnd/Representation.o ) FrontEnd/Representation.hs:350:8: parse error on input `instance' jhc$ am using 6.6.1 ghc, happy is 1.16 and DrIFT version is 2.2.3; would really appreciate if you could let me know what went wrong. thanks -ganesh

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how to use jhc
by Samuel Bronson 07 Oct '07

07 Oct '07

Oops. I've forgotten how to use mailing lists! Here goes again ;-). On 10/6/07, Isaac Dupree <isaacdupree(a)charter.net> wrote: > BTW. my hello world program 'main=putStrLn"hello"' ran correctly using > this jhc. I seem to remember getting hell.hs working before, so that's not too surprising ;-). A copy of hell.hs reproduced from http://paste.lisp.org/display/42132 is attached.

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how to use jhc
by Isaac Dupree 07 Oct '07

07 Oct '07

I'm trying to run Jhc again, following docs/using.txt. "(g)make" works. make install PREFIX=/Users/me/programming/instjhc/ complains install -d "/Users/me/programming/instjhc//bin" install jhc "/Users/me/programming/instjhc//bin" ln -sf "/Users/me/programming/instjhc//bin/jhc" "/Users/me/programming/instjhc//bin/jhci" install -d "/Users/me/programming/instjhc//lib/jhc-0.1" install base-1.0.hl haskell98-1.0.hl "/Users/me/programming/instjhc//lib/jhc-0.1" real_install: cannot stat `base-1.0.hl': No such file or directory real_install: cannot stat `haskell98-1.0.hl': No such file or directory make: *** [install] Error 1 so I tried compiling something without installing Compiling Main.hs 'main=putStrLn"hello"' with any combination of JHCPATH and JHCLIBPATH I tried, errors like this: jhc -vvvv Main.hs jhc 0.1 20071005 (obderaty+0) Compiling [Right "Main.hs"] Loading libraries: ["base","haskell98"] user error (LibraryMap: Library base not found!) Isaac

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Typechecker hiccup?
by Samuel J.J.Bronson 18 Jul '07

18 Jul '07

I just tried to compile this program (based on figure one in "The GRIN Project: A Highly Optimising Back End for Lazy Functional Languages"): {-# OPTIONS_JHC -N -fffi #-} import Jhc.Basics import Jhc.Int import Jhc.Num import Jhc.Order default (Integer, Double) main = sum (upto 1 10) upto m n | m > n = [] | otherwise = m : upto (m+1) n sum [] = 0 sum (x:xs) = x + sum xs And I got a stupid error about a missing "put" method for IORef. It seems that the typechecker isn't getting rid of all the MetaVars in this program...

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foreign import "wrapper"
by Samuel Bronson 16 Jul '07

16 Jul '07

On IRC, you (JohnMeacham) (what -- there is someone else who reads this list?) said something about region inference and foreign import "wrapper". It just occured to me earlier today that you probably can't do much of that at all. You can basically do as much as you can do for a StablePtr. I remind you that the C functions made by a wrapper stub can be passed to C code and held there indefinately, just like a StablePtr, and can only be deallocated when the Haskell program calls freeHaskellFunPtr on them. We also talked about how a nice way to implement these wrapper stubs, by generating tiny thunks that would redirect calls to an evaluation routine after adding the closure to be called as an additional argument. (Actually, I suppose the evaluation routine would need a wrapper, like a foreign export does...). What I'm not sure about is how to refer to the address of the (wrapper around the) evaluation routine in the code for the "wrapper stub" (the function that is actually declared by the 'foreign import "wrapper"' declaration).

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darcs patch: Be more specific about monadic imports, for compatibil...
by Samuel Bronson 16 Jul '07

16 Jul '07

Mon Jul 16 18:15:45 EDT 2007 Samuel Bronson <naesten(a)gmail.com> * Be more specific about monadic imports, for compatibility (especially 6.6/6.6.1)

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darcs patch: Document lookupCType/lookupCType' (and 1 more)
by Samuel Bronson 14 Jul '07

14 Jul '07

Fri Jul 13 13:57:31 EDT 2007 Samuel Bronson <naesten(a)gmail.com> * Document lookupCType/lookupCType' Fri Jul 13 23:00:50 EDT 2007 Samuel Bronson <naesten(a)gmail.com> * Implement "foreign export"

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