Licensing of Haskell code

[Manuel M T Chakravarty]

"Simon Marlow" <simonmar@microsoft.com> wrote,

> It occurs to me that if the reference implementation is GPL, then this
> may encumber the definition of the API such that a commercial
> reimplementation would not be possible.  

I don't think that this is a valid concern.

> In some cases this is
> inevitable - for example, System.Console.Readline wraps a GPL library,
> so there is probably no way to have an unencumbered API definition for
> this library.  

You can always put the API of a library under a BSD license
and the rest under GPL.

> However, we want to avoid having "essential" parts of the
> library definition covered by the GPL.  The library document[1] mentions
> this problem, but doesn't specify exactly what we mean by "essential" -
> we should really expand on that.

As soon as the API of a library is defined in an extra
document, even under the most paranoid interpretation of the
GPL, a library implementation of that API, which is under
the GPL will not affect the license of that API.

I think it is impossible to define what's "essential", AFAIK
the idea was that bindings to, eg, standard system
functionality would be part of a core that is under a BSD
license (as are the Haskell standard modules).

Cheers,
Manuel