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From: augustss@cs.chalmers.se (Lennart Augustsson)
Newsgroups: comp.lang.misc
Subject: Re: Complexity of syntax
Message-ID: <1990Dec19.222059.6878@mathrt0.math.chalmers.se>
Date: 19 Dec 90 22:20:59 GMT
References: <9012061208.AA08577@decpa.pa.dec.com> <1990Dec9.013923.14456@cs.umn.edu> <20@garth.UUCP> <27534.276e5bd3@kuhub.cc.ukans.edu>
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In article <27534.276e5bd3@kuhub.cc.ukans.edu> kinnersley@kuhub.cc.ukans.edu (Bill Kinnersley) writes:
> ..., rather than languages with power. If you want a language with
>
>1) Functions as first-class data (most applicative languages)
>
>2) Arrays (mostly imperative languages)
>
>3) Strong type system
>
>there's nothing left but Algol-68 and C.
>
C does not have functions as first class data, you can only use functions
pointers as data.  To see the difference just try to write a function
that does function composition.  For simplicity assume that all functions
take and return int, i.e. write an
	int (*compose(f, g))()
	int (*f)();
	int (*g)();
(ANSI-fy if you like)
so that (*compose(f,g))(x) == f(g(x)).

I claim that this is impossible to do in a portable way.


	-- Lennart Augustsson
Email:	augustss@cs.chalmers.se