Subject: Re: FOCAL - What I know now and what I'd like to know

From: [email-masked]
Date: Wed, 20 Oct 1993 17:55:37 GMT

>From article <[email-masked]>,
by [email-masked]:
>  
> i : insert ?????
>  
> Now there are two ver important questions I'd like to ask.
>  
> 1) How are conditional operations done. I.e. is there some sort of
>    'if' ?
	That's the I command.  I as in IF.  IF expression a,b,c

	It's the old FORTRAN arithmetic IF statement, goto line a
	if the expression is less than zero, line b if it's equal
	to zero, and line c if it's greater than zero.

	If one of the destination addresses is missing, you fall through
	to the next instruction, possibly the next instruction on the
	same line if semicolons are used as instruction separators.

> 2) Is there a datatype like strings in FOCAL

	Not really.  On input, if you type letters when numbers are
	expected, you get something like A=0, B=1, C=2 ... and so on,
	except E which means "times ten to the".  Numeric constants such
	as 0yes (that's a leading zero) are legal.  As a result, you can
	accept textual input and compare it with the expected 0yes and 0no
	strings, but there's no way to distinguish "k" from "ba", and
	who knows what a "beet" evaluates to.  Don't try to write a
	word processor in FOCAL.

> (Right, I should look in the cs library. Yeah, unfortunatly nothing
>  like a manual could be found.....)

	Look under the title "Programming Lanugages" published by Digital
	Equipment Corporation in various editions in the early 1970's.
	It is Volume 2 of the PDP-8 Handbook Series, and it has chapters
	on FOCAL, FORTRAN, the PAL assembler, and other stuff.

					Doug Jones
					[email-masked]