Hi Kyle,
On Wed, Mar 22, 2023, at 5:29 PM, Kyle Andrews wrote:
> Dear Guix,
>
> Part of my scientific workflow involves compiling a small Racket script
> for a command line program into its executable and placing that on
> PATH.
I am always glad to hear of more people using Guix and Racket together!
> I had bundled this script inside an R package which made sure it
> got compiled and everything was correctly configured at library load
> time.
>
Tangential to your actual question, I think this is not necessarily a terrible
practice. There is not much difference between running `my-script` and running
`racket -y "path/to/my-script.rkt"`, and, if you do that or `raco make` during
the build process of your R package, you'll get compiled files properly. There
are tradeoffs to weigh, including support for R users without Guix. But there
are also good reasons to decide to separate the Racket script from the R
library, so that's what I'll explain below.
> From reading the documentation a lot, I think the actual compilation
> step can be done using the "invoke" procedure like so:
>
> ```
> (invoke "raco" "exe" "{package_location}/custom-shell-tool.rkt")
> ```
>
> What I'm struggling with the most is understanding all the boilerplate
> code I need to place around that fundamental call.
>
I'll start with a working example suitable for `guix build -f`, then answer
your specific questions.
```
;; SPDX-License-Identifier: (CC0-1.0 OR (Apache-2.0 OR MIT))
;; SPDX-FileCopyrightText: Philip McGrath <phi...@philipmcgrath.com>
(use-modules
(gnu packages racket)
(guix build-system copy)
(guix gexp)
(guix packages))
(package
(name "racket-hello")
(version "1.0")
(source (plain-file "hello.rkt"
"#lang racket (displayln '|Hello from Racket!|)"))
(inputs (list racket))
(build-system copy-build-system)
(arguments
(list
#:install-plan #~'(("hello" "bin/"))
#:phases
#~(modify-phases %standard-phases
(add-before 'install 'build
(lambda args
(invoke "raco" "exe" "hello.rkt"))))))
(home-page #f)
(synopsis "Hello world in Racket")
(description
"This is a trivial example of using @code{raco exe} with Guix.")
(license #f))
```
In fact this package would be a reasonable candidate for
`trivial-build-system`, but I've stuck with `copy-build-system` because the
boilerplate for `trivial-build-system` is very different than for all other
build systems.
Likewise, I'm assuming you know how you want to build your executable, but you
might consider the `--launcher` flag for `raco exe` and an explicit call to
`raco make`: in particular, it might take use less total disk space than an ELF
executable.
Note that you do have to use `racket`, not `racket-minimal`, because
`racket-minimal` doesn't include the `raco exe` command.
> (source
> (local-file "package_location")) ; how to refer to local files?
In general, `local-file` is the right mechanism; specifics depend on your
situation, including how you are expecting your package definition to be used.
For a single file, `(local-file "path/to/script.rkt")` is probably what you
want, where the path is relative to the Guile file containing the `local-file`
expression. For a directory, consider the `#:recursive?` and `#:select?`
arguments.
> (invoke "raco" "exe"
> (string-append
> #$package-folder ; how to refer to the build itself?
> "custom-shell-tool.rkt"))))))
The `unpack` phase from `gnu-build-system` handles this: if the package source
is a directory, you're inside a copy of it; if it's a file, you're in a
temporary directory containing it.
>
> I'm especially interested in figuring out how I can productively learn
> to experiment productively with this stuff for myself.
>
Personally, I often insert a phase that calls `error` to stop the build,
perhaps printing out interesting values first, and use `guix build
--keep-failed` to explore the build environment.
-Philip
