Hi,

I'm interested in this composer build system so that I can start packaging the NextCloud server and its dependencies.
I've rebased the patches and modified them a bit:

1. The composer importer now uses the new inputs style for importing
2. The composer build system uses gexps

However, there are a few bugs that I don't know how to fix.

The --recursive option of the importer doesn't work:

===
In guix/scripts/import.scm:
     89:11  4 (guix-import . _)
In guix/scripts/import/composer.scm:ice-9/boot-9.scm:1685:16: In procedure raise-exception:
Throw to key `match-error' with args `("match" "no matching pattern" #<unspecified>)'.

     98:17  3 (guix-import-composer . _)
In guix/import/utils.scm:
    638:27  2 (recursive-import "psr/http-client" # _ #:guix-name _ . #)
    630:33  1 (lookup-node "psr/http-client" #f)
In ice-9/eval.scm:
    423:17  0 (_ . _)

ice-9/eval.scm:423:17: In procedure eval: Wrong number of arguments
===


I think there's something wrong with (define-json-mapping <composer-autoload>:

===
error: in phase 'install': uncaught exception:
match-error "match" "no matching pattern" #<unspecified>

In guix/build/gnu-build-system.scm:
    927:23  6 (_)
In guix/build/composer-build-system.scm:
    200:23  5 (install #:inputs _ #:outputs _ #:composer-file _)
In ice-9/ports.scm:
    433:17  4 (call-with-input-file _ _ #:binary _ #:encoding _ # _)
In guix/build/composer-build-system.scm:
      56:0  3 (json->composer-package (("config" ("allow-plug…" …)) …))
     52:12  2 (json->composer-autoload (("psr-4" ("Doctrine\\…" . #))))
In ice-9/boot-9.scm:
   1685:16  1 (raise-exception _ #:continuable? _)
   1685:16  0 (raise-exception _ #:continuable? _)

ice-9/boot-9.scm:1685:16: In procedure raise-exception:
Throw to key `match-error' with args `("match" "no matching pattern" #<unspecified>)'.
===