From a4c668273df8e726625bf4c8aa828d13bca946f2 Mon Sep 17 00:00:00 2001
From: Alex Vong <alexvong1995@gmail.com>
Date: Sun, 6 Aug 2017 23:43:53 +0800
Subject: [PATCH 6/6] gnu: Add ghc-equivalence.

* gnu/packages/haskell.scm (ghc-equivalence): New variable.
---
 gnu/packages/haskell.scm | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/gnu/packages/haskell.scm b/gnu/packages/haskell.scm
index 33e7af969..60ded9651 100644
--- a/gnu/packages/haskell.scm
+++ b/gnu/packages/haskell.scm
@@ -4714,6 +4714,36 @@ definition of @code{Monad}.")
 for Haskell.")
     (license license:bsd-3)))
 
+(define-public ghc-equivalence
+  (package
+    (name "ghc-equivalence")
+    (version "0.3.2")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append "https://hackage.haskell.org/package/equivalence"
+                           "/equivalence-" version ".tar.gz"))
+       (sha256
+        (base32 "0a85bdyyvjqs5z4kfhhf758210k9gi9dv42ik66a3jl0z7aix8kx"))))
+    (build-system haskell-build-system)
+    (inputs
+     `(("ghc-mtl" ,ghc-mtl)
+       ("ghc-stmonadtrans" ,ghc-stmonadtrans)
+       ("ghc-transformers-compat" ,ghc-transformers-compat)
+       ("ghc-quickcheck" ,ghc-quickcheck)
+       ("ghc-test-framework" ,ghc-test-framework)
+       ("ghc-test-framework-quickcheck2" ,ghc-test-framework-quickcheck2)))
+    (home-page "https://github.com/pa-ba/equivalence")
+    (synopsis
+     "Maintaining an equivalence relation implemented as union-find using STT")
+    (description
+     "This is an implementation of Tarjan's Union-Find algorithm
+(Robert E.@: Tarjan.  \"Efficiency of a Good But Not Linear Set Union
+        Algorithm\",JACM 22(2), 1975) in order to maintain an equivalence relation.
+This implementation is a port of the @code{union-find} package using the ST
+monad transformer (instead of the IO monad).")
+    (license license:bsd-3)))
+
 (define-public ghc-fast-logger
   (package
     (name "ghc-fast-logger")
-- 
2.13.4