40/40: gnu: Add ghc-transformers-0.4.2.0.

[Leo Famulari]

lfam pushed a commit to branch master
in repository guix.

commit 71b611bc34ebb7b1ea86571ed88ce8ff850ccdaa
Author: ng0 <address@hidden>
Date:   Sun Sep 18 16:10:20 2016 +0000

    gnu: Add ghc-transformers-0.4.2.0.
    
    * gnu/packages/haskell.scm (ghc-transformers-0.4.2.0): New variable.
    
    Signed-off-by: Leo Famulari <address@hidden>
---
 gnu/packages/haskell.scm |   13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/gnu/packages/haskell.scm b/gnu/packages/haskell.scm
index 9825dba..dcd21e2 100644
--- a/gnu/packages/haskell.scm
+++ b/gnu/packages/haskell.scm
@@ -6783,6 +6783,19 @@ which automatically lift operations introduced by monad 
transformers through
 other transformers.")
     (license license:bsd-3)))
 
+;; darcs-2.12.0 requires transformers-0.4.2.0
+(define-public ghc-transformers-0.4.2.0
+  (package
+    (inherit ghc-transformers)
+    (version "0.4.2.0")
+    (source (origin
+              (method url-fetch)
+              (uri (string-append 
"https://hackage.haskell.org/package/transformers/";
+                                  "transformers-" version ".tar.gz"))
+              (sha256
+               (base32
+                "0a364zfcm17mhpy0c4ms2j88sys4yvgd6071qsgk93la2wjm8mkr"))))))
+
 (define-public ghc-findbin
   (package
     (name "ghc-findbin")