Re: [racket-dev] Weird bug in Typed Racket predicate for Float 0.0
Hmm, curiouser and curiouser. Using the latest nightly build from http://pre.racket-lang.org/installers/, I get #f #t #t #f both on my home machine and work machine, which run Windows 7 64-bit. Now I'm really curious as to what's going on here! On Fri, Sep 9, 2011 at 12:08 PM, Vincent St-Amour wrote: > At Thu, 8 Sep 2011 20:43:02 -0400, > Luke Vilnis wrote: > > Running this produces: > > > > eq? 0.0 #f > > eqv? 0.0 #t > > Float? #t > > Float-Or-Integer? #f > > With the latest from git on Debian 32 bit, I get `#t' for all four. > > What environment are you using? > > > The part of TR that generates the compound contracts for unions > containing > > Float types is using eq? instead of eqv? for the 0.0 and -0.0 case > (which > > started in version 5.1.1), which explains why the predicate fails. > Somehow, > > in the repro above, a 0.0 is being produced that doesn't eq? with the > > literal 0.0. I tried doing this with, say, (eq? 0.0 (- (+ 3.0 1.0) > > 4.0)) or (eq? > > (exact->inexact 0) 0.0), but those both evaluate to #t, so either the > > compiler is doing some very clever constant folding here, or eq? is > supposed > > to do value equality for floats. I'm assuming the former, but especially > for > > the exact->inexact case that seems pretty darn clever. Anyhow, I was > hoping > > someone could confirm my suspicion that this bug was so hard to reproduce > > because of crazy compiler magic (also, assuming this is right and it's > > simply an eq? vs. eqv? issue, I've sent along a patch). > > The patch looks fine. I'll apply it. > > Thanks! > > Vincent > _ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
[racket-dev] Weird bug in Typed Racket predicate for Float 0.0
Hi all, I think I've found a bug in Typed Racket's predicates, but investigating it raised a lot of questions, so I was hoping someone wouldn't mind explaining what's going on here. A couple weeks ago I wrote a TR program using version 5.1 (like a bonehead, my shortcut to DrRacket was running it out of the wrong directory so I wasn't using the version that I thought I was.) When I recently converted it to 5.1.3, I started noticing intermittent pattern matching failures. I managed to isolate it to the following standalone: #lang typed/racket (define-type Float-Or-Integer (U Float Integer)) (define-predicate Float-Or-Integer? Float-Or-Integer) (define-predicate Float? Float) (define (weird-predicate-behavior) (: integer->float (Integer -> Float)) (define (integer->float int) (exact->inexact int)) (define x (integer->float 0)) (printf "eq? 0.0 ~A ~%" (eq? 0.0 x)) (printf "eqv? 0.0 ~A ~%" (eqv? 0.0 x)) (printf "Float? ~A ~%" (Float? x)) (printf "Float-Or-Integer? ~A" (Float-Or-Integer? x))) Running this produces: eq? 0.0 #f eqv? 0.0 #t Float? #t Float-Or-Integer? #f The part of TR that generates the compound contracts for unions containing Float types is using eq? instead of eqv? for the 0.0 and -0.0 case (which started in version 5.1.1), which explains why the predicate fails. Somehow, in the repro above, a 0.0 is being produced that doesn't eq? with the literal 0.0. I tried doing this with, say, (eq? 0.0 (- (+ 3.0 1.0) 4.0)) or (eq? (exact->inexact 0) 0.0), but those both evaluate to #t, so either the compiler is doing some very clever constant folding here, or eq? is supposed to do value equality for floats. I'm assuming the former, but especially for the exact->inexact case that seems pretty darn clever. Anyhow, I was hoping someone could confirm my suspicion that this bug was so hard to reproduce because of crazy compiler magic (also, assuming this is right and it's simply an eq? vs. eqv? issue, I've sent along a patch). Thanks, Luke 0001-Fixed-a-bug-where-predicates-would-sometimes-fail-to.patch Description: Binary data _ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
[racket-dev] Patch to make the DrRacket "Profile" pane resizable
Hi, Here's a patch that makes it so you can drag to resize the "profile" pane in DrRacket. Apologies if this is the wrong way to submit low-priority tweaks like this, I don't want to clutter up the mailing list. Anyhow, thanks for the Racket toolchain - the "go to definition" and "help desk" right clicks especially have been a big help as I try to learn the libraries. Best, Luke Vilnis 0001-The-Profile-pane-in-DrRacket-can-now-be-dragged-to-r.patch Description: Binary data _ For list-related administrative tasks: http://lists.racket-lang.org/listinfo/dev
