Re: [Caml-list] generic data type -> int function

[Hal Daume III <hdaume@ISI.EDU>]

> On Tue, Mar 29, 2005 at 07:26:02PM -0800, Hal Daume III wrote:
> [...]
> > type etype = GPE | LOC | ORG | PER | NAE_e | BOS_e
> > type mtype = BAR | NAM | NOM | PRE | PRO | OTHER | NAE_m | BOS_m
> > type pairs = EM of etype*mtype | EE of etype*etype | MM of mtype*mtype
> > type pairs2 = EP of etype * pairs | MP of mtype * pairs
> > 
> > 
> > Corresponding output:
> > 
> > let int_of_etype = function | GPE -> 0 | LOC -> 1 | ORG -> 2 | PER -> 3 | NAE_e -> 4 | BOS_e -> 5
> > let int_of_mtype = function | BAR -> 0 | NAM -> 1 | NOM -> 2 | PRE -> 3 | PRO -> 4 | OTHER -> 5 | NAE_m -> 6 | BOS_m -> 7
> > let int_of_pairs = function | EM (etype_0, mtype_1) -> 0 + 1 * (int_of_etype etype_0 + 6 * (int_of_mtype mtype_1)) | EE (etype_0, etype_1) -> 48 + 1 * (int_of_etype etype_0 + 6 * (int_of_etype etype_1)) | MM (mtype_0, mtype_1) -> 84 + 1 * (int_of_mtype mtype_0 + 8 * (int_of_mtype mtype_1))
> > let int_of_pairs2 = function | EP (etype_0, pairs_1) -> 0 + 1 * (int_of_etype etype_0 + 6 * (int_of_pairs pairs_1)) | MP (mtype_0, pairs_1) -> 888 + 1 * (int_of_mtype mtype_0 + 8 * (int_of_pairs pairs_1))
> [...]
> 
> That's nice, but for what do you need this?
> 
> Maybe this way is not necessary to go.
> 
> So, what is this good for?!

I want to use complex data types as indices in arrays, essentially.

-- 
 Hal Daume III                                   | hdaume@isi.edu
 "Arrest this man, he talks in maths."           | www.isi.edu/~hdaume