Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site mit-eddie.UUCP
Path: utzoo!linus!decvax!genrad!mit-eddie!barmar
From: barmar@mit-eddie.UUCP (Barry Margolin)
Newsgroups: net.lang
Subject: Re: Anti-CLU... Anti-Strong-Typing...
Message-ID: <995@mit-eddie.UUCP>
Date: Sat, 3-Dec-83 00:43:09 EST
Article-I.D.: mit-eddi.995
Posted: Sat Dec  3 00:43:09 1983
Date-Received: Sun, 4-Dec-83 08:18:21 EST
References: <411@dartvax.UUCP>, <816@vax2.fluke.UUCP> <666@cbosgd.UUCP>
Organization: MIT, Cambridge, MA
Lines: 23

> ... with lots of superflous conversions going on at runtime.
> PL/1 and APL are like this too.

I have never heard of APL doing any automatic type conversions.
The only types it has are character and numeric, unless you consider the
different types of numeric representations (boolean, integer, and
floating) different types, which APL does not (it just chooses the most
convenient representation at any point).  If you try to use a numeric
operator (e.g. +) on a character value you will get a DOMAIN ERROR.

PL/I does compile-time type checking.  If it notices that a variable of
one type is being used where another is supposed to it will compile code
to do the conversion.  On Multics, where we use PL/I as the primary
systems programming language (those of you who thought that Dennis
Ritchie pioneered this idea are forgetting the history of Unix(tm)) our
compiler generates a warning message whenever it does one of these in an
argument list, since PL/I is normally call-by-reference and this turns
into a pass-by-value which could screw you if the parameter was an
output parameter.
-- 
			Barry Margolin
			ARPA: barmar@MIT-Multics
			UUCP: ..!genrad!mit-eddie!barmar