Adding versioning to our recursive importer

[swedebugia <swedebugia@riseup.net>]

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Hi

I would like some help from someone who understands the recursive importer.

The reason is that in our npm-importer we have to support different 
versions of the same packages to avoid circular dependencies (which 
happen e.g. when importing gulp when not considering versions).

Doing this manually is... not viable. (see the svgz attached)

For every dependency I expect the procedure below to handle a list 
dependency pairs of name+version instead of just name.

Our very nice recursive importer looks like this:

(define* (recursive-import package-name repo
                            #:key repo->guix-package guix-name
                            #:allow-other-keys)
   "Generate a stream of package expressions for PACKAGE-NAME and all its
dependencies."
   (receive (package . dependencies)
       (repo->guix-package package-name repo)
     (if (not package)
         stream-null

         ;; Generate a lazy stream of package expressions for all unknown
         ;; dependencies in the graph.
         (let* ((make-state (lambda (queue done)
                              (cons queue done)))
                (next       (match-lambda
                              (((next . rest) . done) next)))
                (imported   (match-lambda
                              ((queue . done) done)))
                (done?      (match-lambda
                              ((queue . done)
                               (zero? (length queue)))))
                (unknown?   (lambda* (dependency #:optional (done '()))
                              (and (not (member dependency
                                                done))
                                   (null? (find-packages-by-name
                                           (guix-name dependency))))))
                (update     (lambda (state new-queue)
                              (match state
                                (((head . tail) . done)
                                 (make-state (lset-difference
                                              equal?
                                              (lset-union equal? 
new-queue tail)
                                              done)
                                             (cons head done)))))))
           (stream-cons
            package
            (stream-unfold
             ;; map: produce a stream element
             (lambda (state)
               (repo->guix-package (next state) repo))

             ;; predicate
             (negate done?)

             ;; generator: update the queue
             (lambda (state)
               (receive (package . dependencies)
                   (repo->guix-package (next state) repo)
                 (if package
                     (update state (filter (cut unknown? <>
                                                (cons (next state)
                                                      (imported state)))
                                           (car dependencies)))
                     ;; TODO: Try the other archives before giving up
                     (update state (imported state)))))

             ;; initial state
             (make-state (filter unknown? (car dependencies))
                         (list package-name))))))))

Any ideas?

-- 
Cheers Swedebugia

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