build-system: Add haskell-build-system.

* guix/build-system/haskell.scm: New file.
* guix/build/haskell-build-system.scm: New file.
* doc/guix.texi: Add section on 'haskell-build-system'.

doc/guix.texi

@@ -1955,6 +1955,25 @@ Python package is used to run the script can be specified with the
 @code{#:python} parameter.
 @end defvr
 
+@defvr {Scheme Variable} haskell-build-system
+This variable is exported by @code{(guix build-system haskell)}.  It
+implements the Cabal build procedure used by Haskell packages, which
+involves running @code{runhaskell Setup.hs configure
+--prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
+Instead of installing the package by running @code{runhaskell Setup.hs
+install}, to avoid trying to register libraries in the read-only
+compiler store directory, the build system uses @code{runhaskell
+Setup.hs copy}, followed by @code{runhaskell Setup.hs register}.  In
+addition, the build system generates the package documentation by
+running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
+is passed.  Optional Haddock parameters can be passed with the help of
+the @code{#:haddock-flags} parameter.  If the file @code{Setup.hs} is
+not found, the build system looks for @code{Setup.lhs} instead.
+
+Which Haskell compiler is used can be specified with the @code{#:haskell}
+parameter which defaults to @code{ghc}. 
+@end defvr
+
 Lastly, for packages that do not need anything as sophisticated, a
 ``trivial'' build system is provided.  It is trivial in the sense that
 it provides basically no support: it does not pull any implicit inputs,

guix/build-system/haskell.scm

@@ -0,0 +1,135 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Federico Beffa <beffa@fbengineering.ch>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build-system haskell)
+  #:use-module (guix store)
+  #:use-module (guix utils)
+  #:use-module (guix packages)
+  #:use-module (guix derivations)
+  #:use-module (guix build-system)
+  #:use-module (guix build-system gnu)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-26)
+  #:export (haskell-build
+            haskell-build-system))
+
+;; Commentary:
+;;
+;; Standard build procedure for Haskell packages using 'Setup.hs'.  This is
+;; implemented as an extension of 'gnu-build-system'.
+;;
+;; Code:
+
+(define (default-haskell)
+  "Return the default Haskell package."
+  ;; Lazily resolve the binding to avoid a circular dependency.
+  (let ((haskell (resolve-interface '(gnu packages haskell))))
+    (module-ref haskell 'ghc)))
+
+(define* (lower name
+                #:key source inputs native-inputs outputs system target
+                (haskell (default-haskell))
+                #:allow-other-keys
+                #:rest arguments)
+  "Return a bag for NAME."
+  (define private-keywords
+    '(#:target #:haskell #:inputs #:native-inputs))
+
+  (and (not target)                               ;XXX: no cross-compilation
+       (bag
+         (name name)
+         (system system)
+         (host-inputs `(,@(if source
+                              `(("source" ,source))
+                              '())
+                        ,@inputs
+
+                        ;; Keep the standard inputs of 'gnu-build-system'.
+                        ,@(standard-packages)))
+         (build-inputs `(("haskell" ,haskell)
+                         ,@native-inputs))
+         (outputs outputs)
+         (build haskell-build)
+         (arguments (strip-keyword-arguments private-keywords arguments)))))
+
+(define* (haskell-build store name inputs
+                        #:key source
+                        (haddock? #t)
+                        (haddock-flags ''())
+                        (tests? #t)
+                        (test-target "test")
+                        (configure-flags ''())
+                        (phases '(@ (guix build haskell-build-system)
+                                    %standard-phases))
+                        (outputs '("out"))
+                        (search-paths '())
+                        (system (%current-system))
+                        (guile #f)
+                        (imported-modules '((guix build haskell-build-system)
+                                            (guix build gnu-build-system)
+                                            (guix build utils)))
+                        (modules '((guix build haskell-build-system)
+                                   (guix build utils))))
+  "Build SOURCE using HASKELL, and with INPUTS.  This assumes that SOURCE
+provides a 'Setup.hs' file as its build system."
+  (define builder
+    `(begin
+       (use-modules ,@modules)
+       (haskell-build #:name ,name
+                      #:source ,(match (assoc-ref inputs "source")
+                                  (((? derivation? source))
+                                   (derivation->output-path source))
+                                  ((source)
+                                   source)
+                                  (source
+                                   source))
+                      #:configure-flags ,configure-flags
+                      #:haddock-flags ,haddock-flags
+                      #:system ,system
+                      #:test-target ,test-target
+                      #:tests? ,tests?
+                      #:haddock? ,haddock?
+                      #:phases ,phases
+                      #:outputs %outputs
+                      #:search-paths ',(map search-path-specification->sexp
+                                            search-paths)
+                      #:inputs %build-inputs)))
+
+  (define guile-for-build
+    (match guile
+      ((? package?)
+       (package-derivation store guile system #:graft? #f))
+      (#f                                         ; the default
+       (let* ((distro (resolve-interface '(gnu packages commencement)))
+              (guile  (module-ref distro 'guile-final)))
+         (package-derivation store guile system #:graft? #f)))))
+
+  (build-expression->derivation store name builder
+                                #:inputs inputs
+                                #:system system
+                                #:modules imported-modules
+                                #:outputs outputs
+                                #:guile-for-build guile-for-build))
+
+(define haskell-build-system
+  (build-system
+    (name 'haskell)
+    (description "The standard Haskell build system")
+    (lower lower)))
+
+;;; haskell.scm ends here

guix/build/haskell-build-system.scm

@@ -0,0 +1,220 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2015 Federico Beffa <beffa@fbengineering.ch>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (guix build haskell-build-system)
+  #:use-module ((guix build gnu-build-system) #:prefix gnu:)
+  #:use-module (guix build utils)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-26)
+  #:use-module (ice-9 rdelim)
+  #:use-module (ice-9 regex)
+  #:use-module (ice-9 match)
+  #:export (%standard-phases
+            haskell-build))
+
+;; Commentary:
+;;
+;; Builder-side code of the standard Haskell package build procedure.
+;;
+;; The Haskell compiler, to find libraries, relies on a library database with
+;; a binary cache. For GHC the cache has to be named 'package.cache'. If every
+;; library would generate the cache at build time, then they would clash in
+;; profiles. For this reason we do not generate the cache when we generate
+;; libraries substitutes. Instead:
+;;
+;; - At build time we use the 'setup-compiler' phase to generate a temporary
+;;   library database and its cache.
+;;
+;; - We generate the cache when a profile is created.
+;;
+;; Code:
+
+;; Directory where we create the temporary libraries database with its cache
+;; as required by the compiler.
+(define %tmp-db-dir
+  (string-append (or (getenv "TMP") "/tmp")
+                 "/package.conf.d"))
+
+(define (run-setuphs command params)
+  (let ((setup-file (cond
+                     ((file-exists? "Setup.hs")
+                      "Setup.hs")
+                     ((file-exists? "Setup.lhs")
+                      "Setup.lhs")
+                     (else
+                      #f))))
+    (if setup-file
+        (begin
+          (format #t "running \"runhaskell Setup.hs\" with command ~s \
+and parameters ~s~%"
+                  command params)
+          (zero? (apply system* "runhaskell" setup-file command params)))
+        (error "no Setup.hs nor Setup.lhs found"))))
+
+(define* (configure #:key outputs inputs tests? (configure-flags '())
+                    #:allow-other-keys)
+  "Configure a given Haskell package."
+  (let* ((out (assoc-ref outputs "out"))
+         (input-dirs (match inputs
+                       (((_ . dir) ...)
+                        dir)
+                       (_ '())))
+         (params (append `(,(string-append "--prefix=" out))
+                         `(,(string-append
+                             "--docdir=" out "/share/doc/"
+                             (package-name-version out)))
+                         `(,(string-append "--package-db=" %tmp-db-dir))
+                         '("--global")
+                         `(,(string-append
+                             "--extra-include-dirs="
+                             (list->search-path-as-string
+                              (search-path-as-list '("include") input-dirs)
+                              ":")))
+                         `(,(string-append
+                             "--extra-lib-dirs="
+                             (list->search-path-as-string
+                              (search-path-as-list '("lib") input-dirs)
+                              ":")))
+                         (if tests?
+                             '("--enable-tests")
+                             '())
+                         configure-flags)))
+    (run-setuphs "configure" params)))
+
+(define* (build #:rest empty)
+  "Build a given Haskell package."
+  (run-setuphs "build" '()))
+
+(define* (install #:rest empty)
+  "Install a given Haskell package."
+  (run-setuphs "copy" '()))
+
+(define (package-name-version store-dir)
+  "Given a store directory STORE-DIR return 'name-version' of the package."
+  (let* ((base (basename store-dir)))
+    (string-drop base
+                 (+ 1 (string-index base #\-)))))
+
+(define (grep rx port)
+  "Given a regular-expression RX including a group, read from PORT until the
+first match and return the content of the group."
+  (let ((line (read-line port)))
+    (if (eof-object? line)
+        #f
+        (let ((rx-result (regexp-exec rx line)))
+          (if rx-result
+              (match:substring rx-result 1)
+              (grep rx port))))))
+
+(define* (setup-compiler #:key system inputs outputs #:allow-other-keys)
+  "Setup the compiler environment."
+  (let* ((haskell (assoc-ref inputs "haskell"))
+         (name-version (package-name-version haskell)))
+    (cond
+     ((string-match "ghc" name-version)
+      (make-ghc-package-database system inputs outputs))
+     (else
+      (format #t
+              "Compiler ~a not supported~%" name-version)))))
+
+(define (make-ghc-package-database system inputs outputs)
+  "Generate the GHC package database."
+  (let* ((haskell  (assoc-ref inputs "haskell"))
+         (input-dirs (match inputs
+                       (((_ . dir) ...)
+                        dir)
+                       (_ '())))
+         (conf-dirs (search-path-as-list
+                     `(,(string-append "lib/" system "-"
+                                       (package-name-version haskell)
+                                       "/package.conf.d"))
+                     input-dirs))
+         (conf-files (append-map (cut find-files <> "\\.conf$") conf-dirs)))
+    (mkdir-p %tmp-db-dir)
+    (for-each (lambda (file)
+                (copy-file file
+                           (string-append %tmp-db-dir "/" (basename file))))
+              conf-files)
+    (zero? (system* "ghc-pkg"
+                    (string-append "--package-db=" %tmp-db-dir)
+                    "recache"))))
+
+(define* (register #:key name system inputs outputs #:allow-other-keys)
+  "Generate the compiler registration file for a given Haskell package.  Don't
+generate the cache as it would clash in user profiles."
+  (let* ((out (assoc-ref outputs "out"))
+         (haskell  (assoc-ref inputs "haskell"))
+         (lib (string-append out "/lib"))
+         (config-dir (string-append lib "/" system
+                                    "-" (package-name-version haskell)
+                                    "/package.conf.d"))
+         (id-rx (make-regexp "^id: *(.*)$"))
+         (lib-rx (make-regexp "lib.*\\.(a|so)"))
+         (config-file (string-append config-dir "/" name ".conf"))
+         (params
+          (list (string-append "--gen-pkg-config=" config-file))))
+    (unless (null? (find-files lib lib-rx))
+      (mkdir-p config-dir)
+      (run-setuphs "register" params)
+      (let ((config-file-name+id
+             (call-with-ascii-input-file config-file (cut grep id-rx <>))))
+        (rename-file config-file
+                     (string-append config-dir "/" config-file-name+id
+                                    ".conf"))))
+    #t))
+
+(define* (check #:key tests? test-target #:allow-other-keys)
+  "Run the test suite of a given Haskell package."
+  (if tests?
+      (run-setuphs test-target '())
+      (begin
+        (format #t "test suite not run~%")
+        #t)))
+
+(define* (haddock #:key outputs haddock? haddock-flags #:allow-other-keys)
+  "Run the test suite of a given Haskell package."
+  (if haddock?
+      (let* ((out (assoc-ref outputs "out"))
+             (doc-src (string-append (getcwd) "/dist/doc"))
+             (doc-dest (string-append out "/share/doc/"
+                                      (package-name-version out))))
+        (if (run-setuphs "haddock" haddock-flags)
+            (begin
+              (copy-recursively doc-src doc-dest)
+              #t)
+            #f))
+      #t))
+
+(define %standard-phases
+  (modify-phases gnu:%standard-phases
+    (add-before configure setup-compiler setup-compiler)
+    (add-after install haddock haddock)
+    (add-after install register register)
+    (replace install install)
+    (replace check check)
+    (replace build build)
+    (replace configure configure)))
+
+(define* (haskell-build #:key inputs (phases %standard-phases)
+                        #:allow-other-keys #:rest args)
+  "Build the given Haskell package, applying all of PHASES in order."
+  (apply gnu:gnu-build
+         #:inputs inputs #:phases phases
+         args))
+
+;;; haskell-build-system.scm ends here