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From: fs@caesar.cs.tulane.edu (Frank Silbermann)
Newsgroups: comp.lang.functional
Subject: Re: A question about types in ML
Message-ID: <4987@rex.cs.tulane.edu>
Date: 16 Nov 90 17:22:33 GMT
References: <2215@opal.cs.tu-berlin.de> <4971@rex.cs.tulane.edu> <11901@life.ai.mit.edu>
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Organization: Computer Science Dept., Tulane Univ., New Orleans, LA
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In article <11901@life.ai.mit.edu> tmb@ai.mit.edu writes:
>In article <4971@rex.cs.tulane.edu>, fs@caesar.cs.tulane.edu (Frank Silbermann) writes:
>|> >>		Because compromise between flexibility and safety
>|> >>		will always involve a trade-off, I believe that
>|> >>		untyped functional languages (e.g. those in the
>|> >>		LISP/Scheme style) will never become completely obsolete.
>|> 
>|> >	In the very rare case, this property is to be just an object ... 
>|> 	       ^^^^^^^^^
>|> If you remove the imperative features from the core of Common Lisp,
>|> and remove the features which allow function definitions
>|> to be disassembled as lists, what remains _can_ be viewed
>|> as a functional language in which all expressions
>|> denote elements of the recursive domain
>|> 
>|> 	D = (Atoms + Booleans + DxD + D->D)_bottom.
>
>Of course, you can use ML in the same way:
>
>datatype D = Atom of string | Bool of bool | Int of int |
>	     Real of real | Cons of (D * D) | Vector of (D array)

I didn't know that -- thank you for correcting me.
At least now we've finally answered the original question
of <11901@life.ai.mit.edu> re how one can create
an ML list of "anything".  Just define datatype D as above,
and then declare "list D".

	Frank Silbermann	fs@cs.tulane.edu
	Tulane University	New Orleans, Louisianna  USA