How to get started using GWL 0.2.0

[Jelle Licht <jlicht@fsfe.org>]

Hey GWL-hackers,

Congratulations on the 0.2.0 release! After re-reading the info manual,
but not understanding all parts, I keep running into the problem of not
actually being totally sure on how to do some fairly basic things.

How do I install GWL, while using a `guix pull'-managed guix (so with
guile3.0)? As the `guix' that is a propagated input still uses guile2.2,
this is not as simple as I had hoped it would be.

Currently, I have the following wrapper in $HOME/.local/bin/gwl:
--8<---------------cut here---------------start------------->8---
#!/usr/bin/env bash
export GUILE_LOAD_PATH=$HOME/.guix-profile/share/guile/site/2.2
export GUILE_LOAD_COMPILED_PATH=$HOME/.guix-profile/lib/guile/2.2/site-ccache:$HOME/.guix-profile/share/guile/site/2.2
$HOME/.guix-profile/bin/guix workflow "$@"
--8<---------------cut here---------------end--------------->8---

This wrapper seems to work for stuff like `gwl --help' and `gwl
--prepare=<file>'. I'd much rather prefer something less terribad though
:).

My other issue relates to actually running computations usings
GWL. Given the following workflow file:

--8<---------------cut here---------------start------------->8---
process hello-world
  # { echo "Hello, world!" }

workflow do-the-thing
  processes hello-world
--8<---------------cut here---------------end--------------->8---

I can run GWL to both prepare and graph my workflow, yet I get the
following backtrace when trying actually `gwl --run=<file>':

--8<---------------cut here---------------start------------->8---
Backtrace:
          10 (apply-smob/1 #<catch-closure 7f8598ac68c0>)
In ice-9/boot-9.scm:
    705:2  9 (call-with-prompt _ _ #<procedure default-prompt-handler (k proc)>)
In ice-9/eval.scm:
    619:8  8 (_ #(#(#<directory (guile-user) 7f8598744140>)))
In guix/ui.scm:
  1813:12  7 (run-guix-command _ . _)
In guix/scripts/workflow.scm:
   155:24  6 (guix-workflow . _)
In srfi/srfi-1.scm:
   466:18  5 (fold #<procedure 7f8590d7a4c0 at gwl/workflows.scm:246:2 (item acc)> () #)
   466:18  4 (fold #<procedure 7f8590d7a460 at gwl/workflows.scm:249:13 (process res)> …)
In gwl/workflows.scm:
   250:21  3 (_ #<process hello-world> ())
   395:39  2 (_ #<process hello-world> #:workflow _)
In srfi/srfi-1.scm:
  1000:10  1 (lset-intersection #<procedure string=? (#:optional _ _ . _)> _ ())
  1000:38  0 (_ ())

srfi/srfi-1.scm:1000:38: In procedure car: Wrong type argument in position 1 (expecting pair): #t
--8<---------------cut here---------------end--------------->8---

Thanks for any guidance, and feel free to point me to the right section
of The Fine Manual that I simply misunderstood.

- Jelle