There is a weird type-checking bug in 7.0.1 that causes loopy behavior: http://hackage.haskell.org/trac/ghc/ticket/4809 Not sure if that is what is happening to you or not. Though in my experience it did not actually print <<loop>>, it just hung. - jeremy On Jan 25, 2011, at 10:48 AM, Pavel Perikov wrote:

On 25.01.2011, at 18:37, Bjorn Buckwalter wrote:

...

(I suspect the type inferencer is looping), but maybe you've figured out something workable for you already.

I told you I'm exhausted right now, didn't I? :) This is definitely not type inferencer. The bug causes compiled program looping. And I have at least one case when let-trick fixes the behavior in compiled program.

Pavel.

...

Thanks, Bjorn

(Sorry for the re-repost, Pavel, my incompetence is matched only by my perseverance.)

On Tue, Jan 25, 2011 at 22:02, Pavel Perikov wrote:

...

in ghci: Prelude> import Numeric.Units.Dimensional.Prelude as D Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ let s = 9 *~ (meter D.* meter) in s 3.0 m Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ 9 *~ (meter D.* meter) ghci hangs. complied and optimized code detects <<loop>> and let-trick from the above does not help. Here's the complete ghci -v session which contains all package versions

ghci -v GHCi, version 7.0.1: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.0.1, for Haskell 98, stage 2 booted by GHC version 6.12.3 Using binary package database: /Library/Frameworks/GHC.framework/Versions/7.0.1-i386/usr/lib/ ghc-7.0.1/package.conf.d/package.cache Using binary package database: /Users/pavel/.ghc/i386-darwin-7.0.1/package.conf.d/package.cache hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: -static Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> import Numeric.Units.Dimensional.Prelude as D hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ let s = 9 *~ (meter D.* meter) in s hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: Loading package old-locale-1.0.0.2 ... linking ... done. Loading package time-1.2.0.3 ... linking ... done. Loading package numtype-1.0 ... linking ... done. Loading package dimensional-0.8.0.1 ... linking ... done. 3.0 m hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ 9 *~ (meter D.* meter) hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: HANG!

_______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users

Right; it's a bug all right. Happily, I committed a major patch two weeks ago, which cures the bug (I checked). The fix will be in 7.0.2. Meanwhile, if you can build the HEAD or get a development snapshot, you should be good to do. Thanks for reporting this Simon From: glasgow-haskell-users-bounces@haskell.org [mailto:glasgow-haskell-users-bounces@haskell.org] On Behalf Of Pavel Perikov Sent: 25 January 2011 19:44 To: Jeremy Shaw Cc: glasgow-haskell-users@haskell.org Subject: Re: GHC 7.0.1 (or very strange dimensional-0.8.0.1) bug It is NOT type checking bug. It causes Rec {} in core and _|_ in runtime :) On 25.01.2011, at 22:35, Jeremy Shaw wrote: There is a weird type-checking bug in 7.0.1 that causes loopy behavior: http://hackage.haskell.org/trac/ghc/ticket/4809 Not sure if that is what is happening to you or not. Though in my experience it did not actually print <<loop>>, it just hung. - jeremy On Jan 25, 2011, at 10:48 AM, Pavel Perikov wrote: On 25.01.2011, at 18:37, Bjorn Buckwalter wrote: (I suspect the type inferencer is looping), but maybe you've figured out something workable for you already. I told you I'm exhausted right now, didn't I? :) This is definitely not type inferencer. The bug causes compiled program looping. And I have at least one case when let-trick fixes the behavior in compiled program. Pavel. Thanks, Bjorn (Sorry for the re-repost, Pavel, my incompetence is matched only by my perseverance.) On Tue, Jan 25, 2011 at 22:02, Pavel Perikov mailto:perikov@gmail.com> wrote: in ghci: Prelude> import Numeric.Units.Dimensional.Prelude as D Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ let s = 9 *~ (meter D.* meter) in s 3.0 m Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ 9 *~ (meter D.* meter) ghci hangs. complied and optimized code detects <<loop>> and let-trick from the above does not help. Here's the complete ghci -v session which contains all package versions ghci -v GHCi, version 7.0.1: http://www.haskell.org/ghc/ :? for help Glasgow Haskell Compiler, Version 7.0.1, for Haskell 98, stage 2 booted by GHC version 6.12.3 Using binary package database: /Library/Frameworks/GHC.framework/Versions/7.0.1-i386/usr/lib/ghc-7.0.1/package.conf.d/package.cache Using binary package database: /Users/pavel/.ghc/i386-darwin-7.0.1/package.conf.d/package.cache hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Hsc static flags: -static Loading package ghc-prim ... linking ... done. Loading package integer-gmp ... linking ... done. Loading package base ... linking ... done. Loading package ffi-1.0 ... linking ... done. Prelude> import Numeric.Units.Dimensional.Prelude as D hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ let s = 9 *~ (meter D.* meter) in s hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: Loading package old-locale-1.0.0.2 ... linking ... done. Loading package time-1.2.0.3 ... linking ... done. Loading package numtype-1.0 ... linking ... done. Loading package dimensional-0.8.0.1 ... linking ... done. 3.0 m hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. Prelude Numeric.Units.Dimensional.Prelude> D.sqrt $ 9 *~ (meter D.* meter) hiding package containers-0.3.0.0 to avoid conflict with later version containers-0.4.0.0 hiding package QuickCheck-2.3.0.2 to avoid conflict with later version QuickCheck-2.4.0.1 wired-in package ghc-prim mapped to ghc-prim-0.2.0.0-0713122c5f9038c6f0355a37e294e054 wired-in package integer-gmp mapped to integer-gmp-0.2.0.2-bfb191b8468e4d812a2bb92622cb246e wired-in package base mapped to base-4.3.0.0-1ea085b64a078bd9d5eaa9d8d525e35e wired-in package rts mapped to builtin_rts wired-in package template-haskell mapped to template-haskell-2.5.0.0-f262af1f92a427f5cf4133bff041044f wired-in package dph-seq not found. wired-in package dph-par not found. *** Parser: *** Desugar: *** Simplify: *** CorePrep: *** ByteCodeGen: HANG! _______________________________________________ Glasgow-haskell-users mailing list Glasgow-haskell-users@haskell.orgmailto:Glasgow-haskell-users@haskell.org http://www.haskell.org/mailman/listinfo/glasgow-haskell-users