From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00,
	REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,f6b6181765c24743
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-02-05 17:22:54 PST
Path: 
 supernews.google.com!sn-xit-02!sn-xit-01!supernews.com!newsfeed.stanford.edu!arclight.uoregon.edu!newsfeed.ksu.edu!nntp.ksu.edu!news.okstate.edu!dvdeug
From: dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner)
Newsgroups: comp.lang.ada
Subject: Re: Generics - Difference between ADA and Modula--3
Date: 6 Feb 2001 00:03:55 GMT
Organization: Oklahoma State University
Message-ID: <95nf1b$9282@news.cis.okstate.edu>
References: <3a7646fb$1@rsl2.rslnet.net>
 <956ols$qtv$1@news.cis.ohio-state.edu> <95eumd$8i41@news.cis.okstate.edu>
 <95nc12$62m$1@usenet.rational.com>
Reply-To: dstarner98@aasaa.ofe.org
NNTP-Posting-Host: x8b4e5089.dhcp.okstate.edu
User-Agent: slrn/0.9.6.3 (Linux)
Xref: supernews.google.com comp.lang.ada:4957
Date: 2001-02-06T00:03:55+00:00
List-Id: <comp.lang.ada>

On Mon, 5 Feb 2001 15:12:20 -0800, Mark Lundquist <mark@rational.com> wrote:
>> Ada designers made perfectly type-safe generics. Modula-3 designers looked
>> at Ada generics and C++ templates and decided the Ada generics were too
>much
>> of a PITA and went with a C++-style design that catches mistakes at
>link-time
>> rather than compile-time.
>
>Oh yeah... link-time errors, no pain there... :-)

Quote from language reference introduction (which explains the why and how
of many Modula-3 features):

| In the same spirit of simplicity, there is no separate typechecking 
| associated with generics. Implementations are expected to expand the 
| generic and typecheck the result. The alternative would be to invent 
| a polymorphic type system flexible enough to express the constraints 
| on the parameter interfaces that are necessary in order for the generic 
| body to compile. This has been achieved for ML and CLU, but it has not 
| yet been achieved satisfactorily in the Algol family of languages, 
| where the type systems are less uniform. (The rules associated with 
| Ada generics are too complicated for our taste.) 

(Note that this document was written prior to Ada 95.) 
The Introduction (http://www.research.compaq.com/SRC/m3defn/html/intro.html)
is an interesting look at the design of a "Algol family" (i.e. Ada, Oberon, 
the Modula's, Java) and some of the choices that could be made.

-- 
David Starner - dstarner98@aasaa.ofe.org
Pointless website: http://dvdeug.dhis.org
"I don't care if Bill personally has my name and reads my email and 
laughs at me. In fact, I'd be rather honored." - Joseph_Greg