Data.Generics vs. Template Haskell

[Bulat Ziganshin]

Hello Vyacheslav,

Thursday, August 24, 2006, 11:51:46 PM, you wrote:

> I am trying to figure out where these two libraries stand in relation
> to each other and which one is preferred to do generic programming in
> Haskell. I understand that their goals often intersect but couldn't
> find any good comparisons. Could someone point me in the right
> direction?

search for "generics" on hswiki, you should find a lot of papers. in
particular, there is a new paper that compares many different
approaches to generic programming. in particular, TH is not g.p.
tools, it's just a universal Haskell code generator whcih can be used
to solve particular tasks in this area. but to solve general problem
of defining traversal function what has some general case and a nu,ber
of type-specific cases TH is not very appropriate

TH (and DriFT) are widely used to generate instances like the haskell
compiler itself generates instances for Eq/Show/... and TH,
unlike many g.p. tools does it at compile-time. using TH, you also get
access to field/constructor names

summary: if your task fits into the features provided by g.p. tools,
you will gain a much time using them. if your task need compile-time
code generation (so that generic program will be no slower than
hand-written one) or you need some advanced features which your g.p.
tool doesn't provide - welcome to TH with all its programming
oddities. development of TH routines for g.p. is an order of magnitude
slower (at least!) than doing the same with specialized tool


-- 
Best regards,
 Bulat                            mailto:Bulat.Ziganshin at gmail.com