Modules (Was: Blah blah)

[Hans Aberg]

On 19 May 2008, at 17:54, Han-Wen Nienhuys wrote:

> > My hope was to get to the discussion of using in Lilypond Haskell  
> > like a
> > "import" construct, which I think might help LilyPond users, as  
> > opposed to
> > the current "\include", which I think is more like the C preprocessor
> > "#include", and is trickier to use.
>
> While I agree sight-unseen that the Haskell mechanism is more elegant
> than the C includes, the latter is a fairly simple mechanism, and
> orthogonal to lilypond's namespace handling.  If you come up with any
> improvements, you need to remember that it all has to also work with
> guile's namespace handling in a logical way. Right now \paper and
> \header introduce new scopes, and are implemented in terms of a Guile
> module that import the top-level namespace.

I am aware of that, but I do not know Guile's module system. On thing  
I do not like with Haskell is that if one writes
  module A where
  f :: Int -> String
  f _ = "A.f"
---------------
  module B where
  import A
  f :: Int -> String
  f _ = "A.f"

  b :: Int -> String
  b = f
then this is an error, one has to write
  b = B.f
I would think more logical that if one is in the module B, names of  
it need not be qualified.

There is also a shortcoming when importing names unqualified: I think  
one cannot then easily choose some names to qualified and others not.

> > In Lilypond, I thought that perhaps it was such file setup  
> > problems that
> > causes problems for users.
>
> While the include mechanism is clumsy, last time I looked the most
> common complaint was lack of documentation.  This may have changed in
> the last year due to GDP.  Where are when it comes to usability ?

My original reply was to Karl Hammar said:

> I would be nice to be able to do like
>
>   lilypond a.ly .. o.ly z.ly
>
> i.e. treat a.ly .. o.ly as if they where included in z.ly, without
> having to say so in z.ly.

to which I said it is not needed with the Haskell system. But I think  
there were some discussions about making it easier to share code,  
just set some local fonts.

  Hans