Proposal/Idea: Split up base even further

Neil Mitchell ndmitchell at
Fri May 16 09:40:36 EDT 2008

Hi Twan,

I think this is already being done to some extent - so things that GHC
ties to closely are being moved out of base. See this wiki page:



On Fri, May 16, 2008 at 1:14 AM, Twan van Laarhoven <twanvl at> wrote:
> Hello librarians,
> Here is an idea to resolve some of the problems that remain with the base
> package:
> The problem:
> Users can not update their version of the 'base' package, since it is tied
> to Ghc. If a useful new function is added using it requires updating the
> compiler. On the one hand this puts people off using these new functions. On
> the other hand it also makes updates to for instance Data.List take way
> longer to reach the users because we have to wait for the next Ghc release.
> The proposal:
> User code should NEVER import the library that is now called 'base', it
> should provide an internal API only. For example, base can include the
> modules
>     Internal.Data.List
>     Internal.Control.Monad
>     Internal.IO
>     etc.
> Which are as minimal and low level as possible, containing just the things
> that Ghc RELIES on like:
>  - type classes for which instances can be derived (Eq, Ord, etc.)
>  - data types and classes with syntactic sugar (Bool, [], Num, Monad)
>  - low level stuff like IO and ST and primitives
> In short, everything that is now under Ghc.*, and hopefully less, becomes
> the new base library. In my opinion half of that can still be moved out,
> like most of Ghc.List, Ghc.Enum, Ghc.IO and Ghc.Read.
> The next layer can then consist of many packages like "containers",
> "control", "numeric", "concurrent", "ioref", "file-io", "foreign", etc. For
> example the Data.List module imports Internal.Data.List for the basic list
> data type. It re-exports this, and adds many additional functions that don't
> belong in the minimal base library.
> Thoughts?
> Twan
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