Stepping through Guix code (REPL)

[Pjotr Prins]

I am looking for a way to step through Guix code using Guile REPL.


Q1: 

  
https://www.gnu.org/software/guile/manual/html_node/Single-Stepping-through-a-Procedure_0027s-Code.html#Single-Stepping-through-a-Procedure_0027s-Code

I get

  While compiling expression:
  ERROR: no code for module (ice-9 debugger)

Q2: 

In REPL I can do something like 

  (define-module (gnu packages bioinformatics-test)
    #:use-module (gnu packages ruby)
    #:use-module (gnu packages bioinformatics)
    #:use-module (guix)
    #:use-module (guix build-system)
    :use-module (guix build git)
  )
            
  (define s (open-connection))
  (git-fetch "some_source.git" "c003c1e" "dest_dir")

which fetches the git repo and unpacks it in dest_dir. Pretty cool.

But when it comes to the higher-level git-fetch in git-download.scm I
fail to run that. I am trying something like

  (define-module (gnu packages bioinformatics-test)
    #:use-module (gnu packages bioinformatics)
    #:use-module (guix)
    #:use-module (guix git-download)
    #:use-module (guix hash)
    #:use-module (guix base32)
    )

  (define s (open-connection))
  (define ref (git-reference
                 (url "some_source.git")
                 (commit "c003c1e")
                 ))

  (git-fetch ref 'sha256
                  (base32
                   "0yvkv7pnigvcifas3vcr8sk87xrrb8y9nh9v1yx2p43k0xz1q8vz")
                  "mypackage")

Which does not give errors, but there is no result (supposedly it calls into
the earlier git-fetch). The monadic thing is beyond me, so can someone tell me
how to run this git-fetch procedure from REPL? :) It probably needs to be
called from build.

Pj.