import: stackage: Support recursive importing.

* guix/import/hackage.scm (hackage-name->package-name): Export procedure.
* guix/import/stackage.scm (lts-info-packages-lts-info): Fix match expression.
(stackage-recursive-import): New procedure.
(stackage->guix-package): Memoize results.
* guix/scripts/import/stackage.scm (show-help, %options,
guix-import-stackage): Support recursive importing.
* doc/guix.texi (Invoking guix import): Document option.

doc/guix.texi

@@ -6699,9 +6699,14 @@ Specific command-line options are:
 @itemx -t
 Do not include dependencies required only by the test suites.
 @item --lts-version=@var{version}
-@itemx -r @var{version}
+@itemx -l @var{version}
 @var{version} is the desired LTS release version.  If omitted the latest
 release is used.
+@item --recursive
+@itemx -r
+Traverse the dependency graph of the given upstream package recursively
+and generate package expressions for all those packages that are not yet
+in Guix.
 @end table
 The command below imports metadata for the @code{HTTP} Haskell package

guix/import/hackage.scm

@@ -44,6 +44,7 @@ (define-module (guix import hackage)
             %hackage-updater
 
             guix-package->hackage-name
+            hackage-name->package-name
             hackage-fetch
             hackage-source-url
             hackage-cabal-url

guix/import/stackage.scm

 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2017 Federico Beffa <beffa@fbengineering.ch>
+;;; Copyright © 2018 Ricardo Wurmus <rekado@elephly.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -25,10 +26,12 @@ (define-module (guix import stackage)
   #:use-module (srfi srfi-35)
   #:use-module (guix import json)
   #:use-module (guix import hackage)
+  #:use-module (guix import utils)
   #:use-module (guix memoization)
   #:use-module (guix packages)
   #:use-module (guix upstream)
   #:export (stackage->guix-package
+            stackage-recursive-import
             %stackage-updater))
 
 
@@ -45,9 +48,9 @@ (define (lts-info-ghc-version lts-info)
     (_ #f)))
 
 (define (lts-info-packages lts-info)
-  "Retruns the alist of packages contained in LTS-INFO."
+  "Returns the alist of packages contained in LTS-INFO."
   (match lts-info
-    ((_ ("packages" pkg ...)) pkg)
+    ((("packages" pkg ...) . _) pkg)
     (_ '())))
 
 (define (leave-with-message fmt . args)
@@ -85,25 +88,33 @@ (define (lts-package-version pkgs-info name)
 (define (hackage-name-version name version)
   (and version (string-append  name "@" version)))
 
-(define* (stackage->guix-package package-name ; upstream name
-                                 #:key
-                                 (include-test-dependencies? #t)
-                                 (lts-version "")
-                                 (packages-info
-                                  (lts-info-packages
-                                   (stackage-lts-info-fetch lts-version))))
-  "Fetch Cabal file for PACKAGE-NAME from hackage.haskell.org.  The retrieved
+(define stackage->guix-package
+  (memoize
+   (lambda* (package-name ; upstream name
+             #:key
+             (include-test-dependencies? #t)
+             (lts-version "")
+             (packages-info
+              (lts-info-packages
+               (stackage-lts-info-fetch lts-version))))
+     "Fetch Cabal file for PACKAGE-NAME from hackage.haskell.org.  The retrieved
 vesion corresponds to the version of PACKAGE-NAME specified in the LTS-VERSION
 release at stackage.org.  Return the `package' S-expression corresponding to
 that package, or #f on failure.  PACKAGES-INFO is the alist with the packages
 included in the Stackage LTS release."
-  (let* ((version (lts-package-version packages-info package-name))
-         (name-version (hackage-name-version package-name version)))
-    (if name-version
-        (hackage->guix-package name-version
-                               #:include-test-dependencies?
-                               include-test-dependencies?)
-        (leave-with-message "~a: Stackage package not found" package-name))))
+     (let* ((version (lts-package-version packages-info package-name))
+            (name-version (hackage-name-version package-name version)))
+       (if name-version
+           (hackage->guix-package name-version
+                                  #:include-test-dependencies?
+                                  include-test-dependencies?)
+           (leave-with-message "~a: Stackage package not found" package-name))))))
+
+(define (stackage-recursive-import package-name . args)
+  (recursive-import package-name #f
+                    #:repo->guix-package (lambda (name repo)
+                                           (apply stackage->guix-package (cons name args)))
+                    #:guix-name hackage-name->package-name))
 
 
 ;;;

guix/scripts/import/stackage.scm

 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2017 Federico Beffa <beffa@fbengineering.ch>
+;;; Copyright © 2018 Ricardo Wurmus <rekado@elephly.net>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -26,6 +27,7 @@ (define-module (guix scripts import stackage)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-37)
+  #:use-module (srfi srfi-41)
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
   #:export (guix-import-stackage))
@@ -43,11 +45,13 @@ (define (show-help)
   (display (G_ "Usage: guix import stackage PACKAGE-NAME
 Import and convert the LTS Stackage package for PACKAGE-NAME.\n"))
   (display (G_ "
-  -r VERSION, --lts-version=VERSION
+  -l VERSION, --lts-version=VERSION
                                specify the LTS version to use"))
   (display (G_ "
   -h, --help                   display this help and exit"))
   (display (G_ "
+  -r, --recursive              import packages recursively"))
+  (display (G_ "
   -t, --no-test-dependencies   don't include test-only dependencies"))
   (display (G_ "
   -V, --version                display version information and exit"))
@@ -68,11 +72,14 @@ (define %options
                    (alist-cons 'include-test-dependencies? #f
                                (alist-delete 'include-test-dependencies?
                                              result))))
-         (option '(#\r "lts-version") #t #f
+         (option '(#\l "lts-version") #t #f
                  (lambda (opt name arg result)
                    (alist-cons 'lts-version arg
                                (alist-delete 'lts-version
                                              result))))
+         (option '(#\r "recursive") #f #f
+                 (lambda (opt name arg result)
+                   (alist-cons 'recursive #t result)))
          %standard-import-options))
 
 
@@ -90,6 +97,27 @@ (define (parse-options)
                   (alist-cons 'argument arg result))
                 %default-options))
 
+  (define (run-importer package-name opts error-fn)
+    (let* ((arguments (list
+                       package-name
+                       #:include-test-dependencies?
+                       (assoc-ref opts 'include-test-dependencies?)
+                       #:lts-version (assoc-ref opts 'lts-version)))
+           (sexp (if (assoc-ref opts 'recursive)
+                     ;; Recursive import
+                     (map (match-lambda
+                            ((and ('package ('name name) . rest) pkg)
+                             `(define-public ,(string->symbol name)
+                                ,pkg))
+                            (_ #f))
+                          (reverse
+                           (stream->list
+                            (apply stackage-recursive-import arguments))))
+                     ;; Single import
+                     (apply stackage->guix-package arguments))))
+      (unless sexp (error-fn))
+      sexp))
+
   (let* ((opts (parse-options))
          (args (filter-map (match-lambda
                             (('argument . value)
@@ -99,15 +127,11 @@ (define (parse-options)
     (match args
       ((package-name)
        (with-error-handling
-        (let ((sexp (stackage->guix-package
-                     package-name
-                     #:include-test-dependencies?
-                     (assoc-ref opts 'include-test-dependencies?)
-                     #:lts-version (assoc-ref opts 'lts-version))))
-          (unless sexp
-            (leave (G_ "failed to download cabal file for package '~a'~%")
-                   package-name))
-          sexp)))
+         (run-importer package-name opts
+                       (lambda ()
+                         (leave (G_ "failed to download cabal file \
+for package '~a'~%")
+                                package-name)))))
       (()
        (leave (G_ "too few arguments~%")))
       ((many ...)