Hi Timothy,

On Sun 20 Jan 2019 at 17:26 Timothy Sample wrote:

> You should be able to remove the “ghc-mtl” input from the MPD package
> without any issue.

Indeed and it works even better, so here is the new patch:

* gnu/packages/mpd.scm (ghc-libmpd): New variable.
---
 gnu/packages/mpd.scm | 35 +++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/gnu/packages/mpd.scm b/gnu/packages/mpd.scm
index 3fe5d06f4..df4f64470 100644
--- a/gnu/packages/mpd.scm
+++ b/gnu/packages/mpd.scm
@@ -6,6 +6,7 @@
 ;;; Copyright © 2015 Paul van der Walt <paul@denknerd.org>
 ;;; Copyright © 2016, 2018 Leo Famulari <leo@famulari.name>
 ;;; Copyright © 2018 Tobias Geerinckx-Rice <me@tobias.gr>
+;;; Copyright © 2019 Gabriel Hondet <gabrielhondet@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -31,6 +32,7 @@
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system meson)
   #:use-module (guix build-system python)
+  #:use-module (guix build-system haskell)
   #:use-module (gnu packages avahi)
   #:use-module (gnu packages boost)
   #:use-module (gnu packages gcc)
@@ -51,6 +53,8 @@
   #:use-module (gnu packages pkg-config)
   #:use-module (gnu packages python)
   #:use-module (gnu packages python-xyz)
+  #:use-module (gnu packages haskell)
+  #:use-module (gnu packages haskell-check)
   #:use-module (gnu packages pulseaudio)
   #:use-module (gnu packages sqlite)
   #:use-module (gnu packages video)
@@ -360,3 +364,34 @@ Daemon (MPD).  It supports playlists, multiple profiles (connecting to different
 MPD servers, search and multimedia key support.")
     (home-page "https://www.nongnu.org/sonata/")
     (license license:gpl3+)))
+
+(define-public ghc-libmpd
+  (package
+    (name "ghc-libmpd")
+    (version "0.9.0.9")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (string-append
+             "https://hackage.haskell.org/package/libmpd/libmpd-"
+             version
+             ".tar.gz"))
+       (sha256
+        (base32
+         "1931m23iqb4wddpdidm4ph746zpaw41kkjzmb074j7yyfpk7x1jv"))))
+    (build-system haskell-build-system)
+    (inputs
+     `(("ghc-attoparsec" ,ghc-attoparsec)
+       ("ghc-old-locale" ,ghc-old-locale)
+       ("ghc-text" ,ghc-text)
+       ("ghc-data-default-class" ,ghc-data-default-class)
+       ("ghc-network" ,ghc-network)
+       ("ghc-utf8-string" ,ghc-utf8-string)))
+    (native-inputs
+     `(("ghc-quickcheck" ,ghc-quickcheck)
+       ("ghc-hspec" ,ghc-hspec)
+       ("hspec-discover" ,hspec-discover)))
+    (home-page "http://github.com/vimus/libmpd-haskell#readme")
+    (synopsis "MPD client library")
+    (description "A client library for MPD, the Music Player Daemon.")
+    (license license:expat)))
-- 
2.20.1

Thanks for your help!
Gabriel