Hi,
I am trying to create racket distribution for my application, except I
am tripping on my first few steps - that of generating the binary.
First, the architecture of the application. There is a driver program
that is configured with a backend at run-time (although one can argue
this should be a compile time configuration - happy to change that).
The configuration that matches the driver to the backend is an
environment relative path - which is then used to dynamic-require the
backend.
The tree looks like:
`|- info.rkt
|- driver.rkt
|- build.rkt
|
`-archs
|- intel
| `- name.rkt
`- arm
`- name.rkt
info.rkt:
#lang info
(define collection 'multi)
;------------------------
driver.rkt:
#lang racket
(unless (getenv "ARCH")
(raise-user-error 'driver "Please define ARCH with suitable path"))
(define arch-path (getenv "ARCH"))
(define arch-name-path
(build-path arch-path "name.rkt"))
(module+ main
(define arch-proc
(dynamic-require arch-name-path
'get-arch))
(printf "loading arch ~a~n" (arch-proc)))
;------------------------
archs/intel/name.rkt
#lang racket
(provide get-arch)
(define (get-arch)
(if (fixnum? (expt 2 32))
'x86_64
'i386))
;------------------------
archs/arm/name.rkt
#lang racket
(provide get-arch)
;; Support for 32bits arm only
(define (get-arch)
'arm32)
So far so good.
$ raco pkg install --link --auto
$ ARCH=archs/intel racket driver.rkt
loading arch x86_64
$ ARCH=archs/arm racket driver.rkt
loading arch arm32
Not, I try to create an executable using raco exe:
$ mkdir bin
$ raco exe ++lib archs/intel/name.rkt ++lib archs/arm/name.rkt -o
bin/r-prog driver.rkt
$ ARCH=archs/intel bin/r-prog
loading arch x86_64
$ cd bin
$ ARCH=archs/intel ./r-prog
open-input-file: cannot open module file
module path: /home/pmatos/tmp/racket-distro/bin/archs/intel/name.rkt
This doesn't work but it's understandable. However, if only I could
replicate this behaviour in a build script using
create-embedding-executable:
build.rkt:
#lang racket
(require compiler/embed)
(create-embedding-executable
"prog"
#:verbose? #t
#:modules (list (list #f '(file "driver.rkt"))
(list #f '(file "archs/intel/name.rkt"))
(list #f '(file "archs/arm/name.rkt")))
#:configure-via-first-module? #t
#:literal-expression
(parameterize ([current-namespace (make-base-namespace)])
(compile
`(begin
(namespace-require ''driver))))
#:cmdline (list "-U" "--"))
(make-directory* "bin")
(delete-directory/files "bin/prog" #:must-exist? #f)
(copy-directory/files "prog" "bin/prog")
(delete-directory/files "prog")
$ ARCH=archs/intel bin/prog
This finishes successfully and returns nothing which makes me think that
nothing is being executed. This is slightly different from the error I
initially had but I am quite lost with the inner workings of
create-embedding-executable and am using examples online to guide me
which are few and don't really deal exactly with the kind of program I
am trying to compile.
At this point I have a few questions:
1. It is still not clear what the first element in each sublist in
#:modules exactly represents. I understand that it is related to a
module prefix but I don't understand how any value besides #f is useful.
The example in the docs has #f so I used that. Can someone clarify the
usefulness of having a prefix or #t?
2. All examples I have seen create a new namespace in literal-expression
and then use namespace-require. Why can't I just do (require ...) in the
literal-expression?
3. I will have some problems once I got the basics to work with paths. I
assume the solution is define-runtime-path.
I tried
(define-runtime-path arch-path (getenv "ARCH"))
but this will, I think, evaluate the value at both compile time and
runtime which means I will potentially get two different values for
arch-path depending if I am compiling or executing. This also means I am
moving the backend configuration to compile time which is ok but how can
I get the variable at compile time, and then cache that for use at runtime?
I tried
(define-for-syntax foo (getenv "FOO"))
(define-runtime-path p (build-path foo "name.rkt"))
but this will tell me foo is not available at runtime, so I sort of need
to move the compile-time value to runtime. Maybe I am over-complicating
this though so I am happy to hear some comments on this.
Kind regards,
--
Paulo Matos
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