03/03: import: hackage: Handle unknown packages gracefully.

[Federico Beffa]

beffa pushed a commit to branch master
in repository guix.

commit a4824c60ef5ffc0cae3771a16524287904a1c8bd
Author: Federico Beffa <address@hidden>
Date:   Thu Feb 9 17:05:41 2017 +0100

    import: hackage: Handle unknown packages gracefully.
    
    * guix/import/hackage.scm (hackage-fetch): Add 'guard'.
---
 guix/import/hackage.scm | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/guix/import/hackage.scm b/guix/import/hackage.scm
index 4d01ed2..2c9df07 100644
--- a/guix/import/hackage.scm
+++ b/guix/import/hackage.scm
@@ -21,6 +21,7 @@
 (define-module (guix import hackage)
   #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
+  #:use-module (srfi srfi-34)
   #:use-module (srfi srfi-26)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-1)
@@ -115,12 +116,15 @@ version is returned."
   "Return the Cabal file for the package NAME-VERSION, or #f on failure.  If
 the version part is omitted from the package name, then return the latest
 version."
-  (let-values (((name version) (package-name->name+version name-version)))
-    (let* ((url (hackage-cabal-url name version))
-           (port (http-fetch url))
-           (result (read-cabal (canonical-newline-port port))))
-      (close-port port)
-      result)))
+  (guard (c ((and (http-get-error? c)
+                  (= 404 (http-get-error-code c)))
+             #f))                       ;"expected" if package is unknown
+    (let-values (((name version) (package-name->name+version name-version)))
+      (let* ((url (hackage-cabal-url name version))
+             (port (http-fetch url))
+             (result (read-cabal (canonical-newline-port port))))
+        (close-port port)
+        result))))
 
 (define string->license
   ;; List of valid values from