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Date: -- (:)
From: Andrew Lenharth <andrewl@d...>
Subject: Re: [Caml-list] newbie type problem
> 	Yeah, but I still couldn't figure out how to make a Map, assuming 
> that's what I really wanted in the first place.  A hash table that 
> iterates in key sorted order would make my app faster and reduce 
> complexity.  I want to see it actually work first, though.  :)

Yes, making a map is non-obvious.  One first has to figure out the 
module system, with no examples.  Here is a hint:

module StringSet = Set.Make(struct type t = string let compare x y = 
compare x y end)

then you can do things like
StringSet.mem n1 set;;
StringSet.union s1 s2;;
StringSet.add x StringSet.empty;;

BTW: I am sure you can do the compare without the x y by 
compare=compare.

A bit about what is going on.  Set is a parameratized module which you 
must narrow to what you want.  So you use the Make function to return a 
module with the types you want.  They you can use this module in your 
code.

Good examples of this are few and far between.

Andrew Lenharth

-- 
"The reasonable man adapts himself to the world; the unreasonable 
one persists in trying to adapt the world to 
himself. Therefore all progress depends on the unreasonable man."
-- George Bernard Shaw

No matter how cynical you become, it's never enough to keep up.
-- Lily Tomlin

Fools ignore complexity; pragmatists suffer it; experts avoid it; 
geniuses remove it.
-- A. Perlis

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