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symbol table containing symbol tables
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Date: -- (:)
From: Jonathan Roewen <jonathan.roewen@g...>
Subject: Re: [Caml-list] symbol table containing symbol tables
I don't believe you can eliminate the type variable (for the values
associated with the keys) from Map's signature. I would personally
just use a Hashtbl instead.

type complicated = Val of int | StrVal of string | SymTableVal of symTable
and symTable = (string, complicated) Hashtbl.t

Jonathan

On 1/3/07, William W Smith <sesquized@sbcglobal.net> wrote:
> In pidgin OCaml I'd like to write something like
>
> type complicated =
>     IVal of int
>     | StrVa, of string
>     | SymTableVal of symTable
> and
>     symTable = Map(string -> complicated)
>
> I tried many variations on using the Map module to implement a recursive
> data structure like this.  I failed miserably.  (The above wasn't the syntax
> I ever used, but it gets the idea across.)
>
> However, when I create an object
> class [ 'key, 'content ] table : ('key -> 'key -> int) ->
> object
> ,,,
> end
>
> I can successfully declare
> type complicated =
>     IVal of int
>     | StrVal of string
>     | SymTableVal of (string, complicated) table
> that does what I want.   Ithis isn't the whole declaration of complicated,
> but I believe once I get this declaration working, the more quirky
> variations work too.
>
> Do I need one of the more advanced features of OCaml that I don't currently
> understand to use Map the way that I want without writing a whole table
> class?  I don't even see how I can use Map from inside the table class to do
> what I want which would also be acceptable.
>
> I don't want to have to break open the Map module to modify it and thus
> change the licensing of my final program.
>
> Thanks
>
> Bill
>
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