Statistics on library imports (was: Re: [Haskell-cafe] Is there a printable copy of the (GHC) library references anywhere?)

Henk-Jan van Tuyl hjgtuyl at
Thu Dec 28 16:52:14 EST 2006

About the usefulness of libraries: I just made some statistics
on imports in Haskell code; I have a lot of Haskell source code
on my disk (mostly downloaded).
In the following table, the number on the left indicates the
number of imports found for each library.

Top twenty of imports:

  418 Data.List
  417 System.IO
  288 Data.Char
  274 Control.Monad
  157 Data.Maybe
  150 Graphics.UI.WX
  144 Control.Exception
  118 Test.HUnit
  105 System.Directory
  103 Data.Word
  101 Prelude
   95 Text.ParserCombinators.Parsec
   84 System.IO.Error
   83 System.IO.Unsafe
   80 System.Exit
   79 Data.Array
   76 Graphics.UI.WXCore
   75 Data.Bits
   73 System.Time
   73 MissingH.Str

     Total number of imports: 8691
     Total number of files:   1918

Henk-Jan van Tuyl

On Wed, 27 Dec 2006 22:00:24 +0100, Neil Mitchell <ndmitchell at>  

> Only a few of the standard libraries are useful unless you are doing
> something specific. i.e. Data.Maybe is generally useful, but
> Control.Monad.State is only useful if you are using a state monad.
> If someone wrote a tour of Data.List/Data.Maybe as well as a few
> common functions out of Control.Monad that would probably make a nice
> companion to a tour of the prelude.
> Thanks

Met vriendelijke groet,
Henk-Jan van Tuyl


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