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From: olm@Eng.Sun.COM (Ole Lehrmann Madsen)
Newsgroups: comp.lang.beta
Subject: Re: a few basic questions
Date: 29 Apr 1995 17:44:37 GMT
Organization: Sun Microsystems Inc., Mountain View, CA
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Thanks for your interest in Beta. Here are some answers:

bakul@netcom.com (Bakul Shah) writes:

>I have been reading the Beta book (Object-Oriented Programming in
>the BETA Programming Language) and have some questions.  I looked
>though the Beta FAQ and various publicly available on-line
>sources but did not find answers to these quesions.

>1. Are Beta identifiers case sensitive?

no. 

>2. Are Beta keywords case sensitive?  In various sources
>   I have seen `INNER' as well as `inner' which leads me
>   to believe may be they are not.

no. 

>3. What characters are allowed in identifiers?  More generally,
>   grammar described in the appendix A of the Beta book does
>   not give any syntax rules for terminals symbols
>   such as identifiers and numbers.

An indentifier has to start with a letter, and may be followed by
a sequence of letters, digits, and '_'.

>4. Syntax for the If-imperative does not specify (if E then I if)
>   as valid but I have seen this syntax used in a number of
>   examples elsewhere (i.e. not in the Beta book).  Which is
>   right?

The 

	(if E then I if)		(if E then I else J if)

were added as an abbreviation for

	(if E // true then I if)	(if E // true then I else J if)

>5. Page 62 shows two forms for labeled imperatives.  The second
>   form ``(L: Imp1; ... :L)'' does not match what is in appendix
>   A.  I suspect appendix A is wrong. Also, what is the `scope'
>   of a label? For example, is ``(L: (L: 1 :L) :L)'' valid?


The 'second' form 

	(L: Imp1; ...; :L)

has been removed form the language. Instead the following may be used

	L: (#do Imp1; .... #)

The compiler inlines inserted items that ONLY have a do-part.

>6. I am curious about why Beta only allows one dimensional arrays.
>   Why is
>	col:(# cell: [columns] @real #);
>	m1: [rows]@col
>   preferable to
>	m1:[rows][columns]@real
>   ?

The argument for this is that basic array mechanism is supposed
to be used to build more advanced array abstractions such as two-dimensional
arrays. The same is true for the simple for-loop.

>I realize that the Beta book is not a formal language reference
>so please don't think of the above questions as a criticism of it.
>I am simply curious.

A language definition manual is currently being written.

---olm

>Thanks for any information.

>Bakul Shah <bakul@netcom.com>