Error with company-mode, using Haskell

Question

I installed haskell-mode, and I follow this tutorial to install company here. But it only ran once; now when I launch Emacs I get this error:

Warning (initialization): An error occurred while loading /home/lowley/.emacs':
File error: Cannot open load file, company
To ensure normal operation, you should investigate and remove the
cause of the error in your initialization file.  Start Emacs with
the --debug-init' option to view a complete error backtrace.

on M-x company-mode, the company mode is activated but if I enter putS it proposes putStrLn only (no putStr) and the mode turns to company-<dabbrev-code.

Here is my emacs config file :

(require 'package)
(custom-set-variables
 '(package-archives
   (quote
    (("gnu" . "http://elpa.gnu.org/packages/")
     ("melpa-stable" . "http://stable.melpa.org/packages/")))))


(custom-set-variables
 '(custom-enabled-themes (quote (misterioso))))
(custom-set-faces
 )

(add-hook 'haskell-mode-hook 'turn-on-haskell-indentation)

(let ((my-cabal-path (expand-file-name "~/.cabal/bin")))
  (setenv "PATH" (concat my-cabal-path ":" (getenv "PATH")))
  (add-to-list 'exec-path my-cabal-path))

(add-to-list 'load-path "~/.cabal/share/ghc-mod-5.4.0.0")

(autoload 'ghc-init "ghc" nil t)
(autoload 'ghc-debug "ghc" nil t)
(add-hook 'haskell-mode-hook (lambda () (ghc-init)))

(require 'company)
(add-hook 'after-init-hook 'global-company-mode)

(add-to-list 'company-backends 'company-ghc)
(custom-set-variables '(company-ghc-show-info t))

Answer 1

If you want to have the ELPA packages activated already when the init script runs, you should call (package-initialize) first.

Answer 2

The error indicates that emacs cannot find the company package when it hits the (require 'company) in your init file. Use M-x list-packages to install it.