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From: Rainer Weikusat <rweikusat@talktalk.net>
Newsgroups: comp.unix.shell,comp.unix.programmer,comp.lang.misc
Subject: Re: Command Languages Versus Programming Languages
Date: Thu, 10 Oct 2024 17:55:32 +0100
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Muttley@DastartdlyHQ.org ignorantly rambled:
> On Thu, 10 Oct 2024 16:09:49 +0100
> Rainer Weikusat <rweikusat@talktalk.net> boring babbled:
>>Muttley@DastartdlyHQ.org writes:
>>> Its syntax is also a horrific mess.
>>
>>Which means precisely what?
>
> Far too much pointless punctuation. An interpreter shouldn't need the vartype
> signified by $ or @ once its defined, it should already know.

For the purpose of variable declaration, how's the interpeter going to
know the type of a variable without being told about it? Obviously, not
at all.

Perl has three builtin types, scalars, arrays and hashes and
each is denoted by a single-letter prefix which effectively creates
three different variable namespaces, one for each type. That's often
convenient, because the same name can be reused for a variable of a
different type, eg:

my ($data, @data, %data);

$data = rand(128);
@data = ($data, $data + 1);
%data = map { $_, 15 } @data;

it's also convenient to type and easy to read due to being concise.

Outside of declarations, $ and @ really denote access modes/ contexts,
with $ standing for "a thing" and @ for "a number of things", eg

$a[0]

is the first element of the array @a and

@a[-3 .. -1]

is a list composed of the three last elements of @a.

> And then there  are semantically meaningful underscores (seriously?)

Similar to the number writing convention in English: 1,600,700, numbers
in Perl can be annotated with _-separators to make them easier to
read. Eg, all of these are identical

1_600_700
16_007_00
1_6_0_0_7_0_0_

But the underscores have no meaning in here.

> and random hacky keywords  such as <STDIN>.

<STDIN> isn't a keyword. STDIN is the name of a glob (symbol table
entry) in the symbol table of the package main. It's most prominent use
is (as they name may suggest) to provide access to "the standard input
stream".

<> is an I/O operator. It's operand must be a file handle, ie, either
the name of glob with a file handle associated with it like STDIN or a
scalar variable used to hold a file handle. In scalar context, it reads
and returns the next line read from this file handle. In list context,
it returns all lines in the file.

Eg, this a poor man's implementation of cat:

perl -e 'open($fh, $_) and print <$fh> for @ARGV'

> I could go on.

Please don't enumerate everything else on this planet you also don't
really understand as that's probably going to become a huge list. ;-)