build-system: haskell: Add ‘hackage-uri’ procedure.

* guix/build-system/haskell (hackage-uri): New procedure.
* guix/import/hackage.scm (hackage-module->sexp, latest-release): Use it.
* tests/hackage.scm (match-ghc-foo, match-ghc-foo-6, match-ghc-foo-revision,
match-ghc-foo-import): Adjust accordingly.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

guix/build-system/haskell.scm

@@ -2,6 +2,7 @@
 ;;; Copyright © 2015 Federico Beffa <beffa@fbengineering.ch>
 ;;; Copyright © 2020 Timothy Sample <samplet@ngyro.com>
 ;;; Copyright © 2020 Simon Tournier <zimon.toutoune@gmail.com>
+;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -30,7 +31,9 @@
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
-  #:export (%haskell-build-system-modules
+  #:export (hackage-uri
+
+            %haskell-build-system-modules
             haskell-build
             haskell-build-system))
 
@@ -41,6 +44,12 @@
 ;;
 ;; Code:
 
+(define (hackage-uri name version)
+  "Return a URI string for the Haskell package hosted on Hackage corresponding
+to NAME and VERSION."
+  (string-append "https://hackage.haskell.org/package/" name "/"
+                 name "-" version ".tar.gz"))
+
 (define %haskell-build-system-modules
   ;; Build-side modules imported by default.
   `((guix build haskell-build-system)

guix/import/hackage.scm

@@ -40,6 +40,7 @@
   #:use-module (guix memoization)
   #:use-module (guix upstream)
   #:use-module (guix packages)
+  #:autoload   (guix build-system haskell) (hackage-uri)
   #:use-module ((guix utils) #:select (call-with-temporary-output-file))
   #:export (%hackage-url
             hackage->guix-package
@@ -303,7 +304,7 @@ the hash of the Cabal file."
         (version ,version)
         (source (origin
                   (method url-fetch)
-                  (uri (string-append ,@(factorize-uri source-url version)))
+                  (uri (hackage-uri ,name version))
                   (sha256
                    (base32
                     ,(if tarball
@@ -367,7 +368,7 @@ respectively."
                (hackage-cabal-url hackage-name))
        #f)
       ((_ *** ("version" (version)))
-       (let ((url (hackage-source-url hackage-name version)))
+       (let ((url (hackage-uri hackage-name version)))
          (upstream-source
           (package (package-name package))
           (version version)

tests/hackage.scm

@@ -170,10 +170,7 @@ library
     ('source
      ('origin
        ('method 'url-fetch)
-       ('uri ('string-append
-              "https://hackage.haskell.org/package/foo/foo-"
-              'version
-              ".tar.gz"))
+       ('uri ('hackage-uri "foo" 'version))
        ('sha256
         ('base32
          (? string? hash)))))
@@ -215,10 +212,7 @@ library
     ('source
      ('origin
        ('method 'url-fetch)
-       ('uri ('string-append
-              "https://hackage.haskell.org/package/foo/foo-"
-              'version
-              ".tar.gz"))
+       ('uri ('hackage-uri "foo" 'version))
        ('sha256
         ('base32
          (? string? hash)))))
@@ -343,10 +337,7 @@ executable cabal
     ('source
      ('origin
        ('method 'url-fetch)
-       ('uri ('string-append
-              "https://hackage.haskell.org/package/foo/foo-"
-              'version
-              ".tar.gz"))
+       ('uri ('hackage-uri "foo" 'version))
        ('sha256
         ('base32
          (? string? hash)))))
@@ -409,10 +400,7 @@ executable cabal
     ('source
      ('origin
        ('method 'url-fetch)
-       ('uri ('string-append
-              "https://hackage.haskell.org/package/foo/foo-"
-              'version
-              ".tar.gz"))
+       ('uri ('hackage-uri "foo" 'version))
        ('sha256
         ('base32
          (? string? hash)))))