[racket] Understanding raco make and its correctness guarantees

FWIW I recall getting confused by this too. (But unlike you, I haven't
detoured at the time to figure out exactly what's going on; instead
I've resorted to `rm -rf compiled/` and resumed whatever I was trying
to get done).

> 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.

If that's the status quo, even just knowing so clearly is helpful.
E.g. if `raco make` docs had a big, "Tip: If you _ever_ use raco make,
_always_ use it, else delete compiled/".

I think a contributing factor for me was that in DrRacket it "just
works", for the reason Robby explained, so later I expected
command-line racket to just-work, too.

On Thu, Mar 21, 2013 at 11:16 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
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