[racket] Understanding raco make and its correctness guarantees

On Thu, Mar 21, 2013 at 10:42 AM, Eric Dobson <eric.n.dobson at gmail.com>wrote:

> I am under the assumption that the compiled directory is just a cache
> of the byte code version of the compiled source code, and that racket
> should use the source code when ever that cache is invalid. This is
> currently not true, as my examples show, yet racket does work to make
> it mostly true. So my question is why doesn't racket do the same check
> that raco make does?
>
>
I believe the concern is that it is expensive (in terms of filesystem
access). This decision was made a very long time ago, tho, and I don't know
if we've done any real measurements or if maybe the balance has changed.


> No I don't want racket to run raco make before requiring the file.
> That would update the compiled directories, (which likely isn't
> expensive, but not the feature I'm asking about).
>
> On Thu, Mar 21, 2013 at 8:34 AM, Tobias Hammer <tobias.hammer at dlr.de>
> wrote:
> > You can use a little 'preload' script:
> >
> > wrap-compile.rkt
> > #lang racket
> > (require compiler/cm)
> > (current-load/use-compiled
> >  (make-compilation-manager-load/use-compiled-handler))
> >
> > and run with racket -t wrap-compile.rkt <more>
> > I would really love to see this functionality as a command line option to
> > the console racket
> >
> > Tobias
> >
> >
> >
> >
> >
> > On Thu, 21 Mar 2013 16:31:51 +0100, Eric Dobson <eric.n.dobson at gmail.com
> >
> > wrote:
> >
> >> So anyone who just uses the command line tools is out of luck? I like
> >> my build system to be correct, and it seems weird that there is work
> >> to make sure the right zo file is matched with the source file but
> >> that it is incorrect in some simple cases.
> >>
> >> On Thu, Mar 21, 2013 at 8:19 AM, Robby Findler
> >> <robby at eecs.northwestern.edu> wrote:
> >>>
> >>> Or use DrRacket and turn on the auto compilation feature. Or set up
> >>> compiler/cm yourself to do that.
> >>>
> >>> Robby
> >>>
> >>>
> >>> On Thu, Mar 21, 2013 at 10:16 AM, Eric Dobson <eric.n.dobson at gmail.com
> >
> >>> wrote:
> >>>>
> >>>>
> >>>> That doesn't explain why I can get the same behavior as the macro with
> >>>> a function call, probably inlining is responsible for that though.
> >>>>
> >>>> So the take away is that if I want my running system to represent the
> >>>> current state of the source files I either need to run raco make every
> >>>> single time, or never run raco make. That seems very counter
> >>>> intuitive.
> >>>>
> >>>> On Thu, Mar 21, 2013 at 1:51 AM, Tobias Hammer <tobias.hammer at dlr.de>
> >>>> wrote:
> >>>> > The difference lies in the method how racket and raco make check for
> >>>> > changes.
> >>>> > - racket only looks at each individual file's timestamp source and
> .zo
> >>>> > timestamp and uses whichever is never.
> >>>> > - raco make always checks if the file has changed or any of its
> >>>> > dependencies
> >>>> > has changed to decide if it has to recompile the file.
> >>>> >
> >>>> > Whats happens in version 1 is that the macro is already expanded in
> >>>> > a.zo
> >>>> > and
> >>>> > a.zo is still never than a.rkt. Therefore racket loads a.zo (but
> >>>> > b.rkt)
> >>>> > and
> >>>> > prints 'version1.
> >>>> > In version 2 raco make (or more correctly compiler/cm) checks a.rkt,
> >>>> > finds
> >>>> > the dependency to b.rkt, notices the change in b.rkt (by
> calculating a
> >>>> > checksum over the whole dependency tree if i remember correct) and
> >>>> > therefore
> >>>> > recompiles a.rkt AND b.rkt.
> >>>> >
> >>>> > Version 3 should as far as i understand never differ, assumed raco
> >>>> > make
> >>>> > works.
> >>>> >
> >>>> > Tobias
> >>>> >
> >>>> >
> >>>> >
> >>>> > On Thu, 21 Mar 2013 06:23:24 +0100, Eric Dobson
> >>>> > <eric.n.dobson at gmail.com>
> >>>> > wrote:
> >>>> >
> >>>> >> I'm trying to understand what are the guarantees that raco make is
> >>>> >> meant to provide. I'm going to limit this to simple programs, no
> >>>> >> fancy
> >>>> >> dynamic requires, or trying to trick the compiler.
> >>>> >>
> >>>> >> In the following scenario:
> >>>> >> 1. Edit files
> >>>> >> 2. run 'raco make <files>'
> >>>> >> 3. Change files
> >>>> >> I expect all of these to have the same effect during the running of
> >>>> >> phase 0 when running racket.
> >>>> >> 4. racket <main-file>
> >>>> >> or
> >>>> >> 4. raco make <files>
> >>>> >> 5. racket <main-file>
> >>>> >> or
> >>>> >> 4. rm -rf compiled/
> >>>> >> 5. raco make <files>
> >>>> >> 6. racket <main-file>
> >>>> >>
> >>>> >> I can make version 1 and 2 differ with the following program:
> >>>> >> a.rkt
> >>>> >> #lang racket
> >>>> >> (require "b.rkt")
> >>>> >> (macro)
> >>>> >>
> >>>> >> #lang racket
> >>>> >> (provide maco)
> >>>> >> (define-syntax (macro stx)
> >>>> >>   #''version1)
> >>>> >>
> >>>> >> Where the edit is changing version1 to version2. I can also
> replicate
> >>>> >> this with a function and not a macro.
> >>>> >>
> >>>> >> I thought I could make version 2 and version 3 differ, but cannot
> >>>> >> seem
> >>>> >> to replicate it now, but it would be helpful to know if I see
> >>>> >> something that is fixed by clearing the compiled directories.
> >>>> >>
> >>>> >> My understanding was that racket used the same logic as raco make
> on
> >>>> >> whether or not to use the compiled versions versus recompiling, and
> >>>> >> this seems to refute that. Can someone give some insight on what I
> >>>> >> should be expecting?
> >>>> >> ____________________
> >>>> >>   Racket Users list:
> >>>> >>   http://lists.racket-lang.org/users
> >>>> >
> >>>> >
> >>>> >
> >>>> > --
> >>>> > ---------------------------------------------------------
> >>>> > Tobias Hammer
> >>>> > DLR / Robotics and Mechatronics Center (RMC)
> >>>> > Muenchner Str. 20, D-82234 Wessling
> >>>> > Tel.: 08153/28-1487
> >>>> > Mail: tobias.hammer at dlr.de
> >>>> ____________________
> >>>>   Racket Users list:
> >>>>   http://lists.racket-lang.org/users
> >>>
> >>>
> >>>
> >
> >
> > --
> > ---------------------------------------------------------
> > Tobias Hammer
> > DLR / Robotics and Mechatronics Center (RMC)
> > Muenchner Str. 20, D-82234 Wessling
> > Tel.: 08153/28-1487
> > Mail: tobias.hammer at dlr.de
>
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