From: mcsun!sun4nl!cwi.nl!dik@uunet.uu.net (Dik T. Winter)
Subject: Re: and then
Date: 10 Apr 93 15:43:08 GMT [thread overview]
Message-ID: <9551@charon.cwi.nl> (raw)
In article <1993Apr10.010355.4244@nosc.mil> sampson@nosc.mil (Charles H. Sampso
n) writes:
> In the original requirements for Ada (Steelman), functions were not
> allowed to have side effects. At least one of the candidate languages,
> Blue if I remember correctly, took a stab at prohibiting them with rules
> about exactly what kind of code a function could and could not contain.
> Somewhere along the way the requirement vanished, either by explicit action
> or benign neglect, probably because the requirement was considered draconi-
> an. By that time I was pretty far out of the loop.
The requirements vanished gradually. At one point there was not a dichotomy
but a trichotomy: functions (pure, no side effects), procedures (pure) and
value-returning procedures. For optimization purposes this is the best, but
value-returning procedures fell out and functions with side-effects came in.
The basic reason for the shift to value-returning procedures was that it is
impossible to write such a basic thing as a random number generator without
side-effects.
--
dik t. winter, cwi, kruislaan 413, 1098 sj amsterdam, nederland
home: bovenover 215, 1025 jn amsterdam, nederland; e-mail: dik@cwi.nl
next reply other threads:[~1993-04-10 15:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
1993-04-10 15:43 Dik T. Winter [this message]
-- strict thread matches above, loose matches on Subject: below --
1993-04-12 18:38 and then Charles H. Sampson
1993-04-12 13:29 cis.ohio-state.edu!zaphod.mps.ohio-state.edu!howland.reston.ans.net!noc.n
1993-04-11 3:55 Michael Feldman
1993-04-10 19:52 Alex Blakemore
1993-04-10 15:36 Dik T. Winter
1993-04-10 9:39 munnari.oz.au!yoyo.aarnet.edu.au!news.adelaide.edu.au!usenet
1993-04-10 1:03 Charles H. Sampson
1993-04-09 18:08 Dave Bashford
1993-04-09 14:06 Dan Rittersdorf
1993-04-08 22:35 Andrew Dunstan,,2285592,
1993-04-08 22:28 Alex Blakemore
1993-04-08 19:03 Art Duncan
1993-04-08 16:18 Charles H. Sampson
1993-04-08 15:34 Christopher J. Henrich
1993-04-08 12:21 enterpoop.mit.edu!usc!cs.utexas.edu!mars.tsd.arlut.utexas.edu!gardner
1993-04-07 22:58 Mark Lundquist
1993-04-07 21:07 Ray Harwood -- Data Basix: (602)721-1988
1993-04-07 16:21 Charles H. Sampson
1993-04-07 12:42 Robert Firth
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