Path: utzoo!utgpu!attcan!uunet!ficc!peter
From: peter@ficc.uu.net (Peter da Silva)
Newsgroups: comp.lang.misc
Subject: Re: Expression Based Language
Message-ID: <2659@ficc.uu.net>
Date: 7 Jan 89 00:23:13 GMT
References: <3300001@uxg.cso.uiuc.edu> <3290002@hpctdls.HP.COM> <11359@haddock.ima.isc.com>
Organization: Xenix Support
Lines: 41

Three comments: First,

	a = for(s1;e;s2)

	Is this legal? If e fails, is the value s1?

also,

	[BCPL resultis...]

	This is equivalent to your 'break(n)', above. I like this very
	much. I didn't do anything like 'resultis', and had break return
	the value of the preceding expression.

and finally,

	For expressions like if-without-else, the value if no statement
	was executed was zero, NULL, whatever. This was in analogy to
	short-circuit AND (which wasn't in the language).

	That is, "a = if(b) then 2" was equivalent to "a = b || 2".

	This also obviated the need for flow analysis, and let me just use
	the value in BC as the result of a statement :->.

...

OK. I think the name "E" is better than "EC". (I called mine "Small-P :->").

How about making break(n) work in any block? Hmmm. No. Hmmm. Maybe resultis
would be better. Simplify it, make it 'result'.

I think the value of a statement with varying types is soluble by looking
at the coercion needed to use it in context. If function prototypes are
mandated, the only problem is printf(). And I think the promotion rules
will work here.
-- 
Peter da Silva, Xenix Support, Ferranti International Controls Corporation.
Work: uunet.uu.net!ficc!peter, peter@ficc.uu.net, +1 713 274 5180.   `-_-'
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