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Re: My problems to understand the Perl documentation

by LanX (Sage)
on Aug 22, 2020 at 21:48 UTC ( #11121000=note: print w/replies, xml ) Need Help??


in reply to My problems to understand the Perl documentation

Some older languages had/have a clear separation - syntactic and semantic - between subroutine and function!

Perl doesn't, but explains the terminology for people coming from there.

perlfunc describes builtin "functions" in CORE::

Most can be replicated with with pure Perl when using prototypes , so those "flat list arguments" don't apply in these cases.

Other built-ins can't be replicated because they require special parsing of their arguments.

The " mathematical function" part is misleading, because Perl's subs can have side-effects, like altering passed or global or closure variables.

Compare that to languages like Haskell which do their best to be side-effect free like mathematical functions.

Operators in perlop are indeed built-in functions with special syntax, context and precedence. You can replicate $a+$b*$c with add( $a, mul( $b, $c ) ) and in some docs you'll find function like built-ins called "operators"

The goal you seem to have is to define Perl in Lisp'ish way, where everything can be derived from a small set of axioms.

I doubt that's possible, because the creators cared more about DWIM than orthogonality.

Perl has loads of influences from C, bash, sed, awk and Lisp and tried to combine them in an "organic" way to make people coming from those ends feal like at home.

Those features were not implemented in a clean canonical mini Perl ...

EDIT

... and there is no language definition like ECMA.

The best possible outcome you can achieve is probably a language definition for 98% of Perl combined with a long list of exceptions.

One simple example: built-ins like map and grep can be replicated with

sub name(&;@) { my ($code, @list) = @_; ... } # then called name {BLOCK} LIST;

BUT having a return inside the BLOCK will lead to a very different result, hence gone the orthogonality.

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

Replies are listed 'Best First'.
Re^2: My problems to understand the Perl documentation
by karlgoethebier (Abbot) on Aug 23, 2020 at 15:50 UTC

    Callable unit isn’t a bad explanation. Or definition. Should be enough. The rest are is «jesuitisch raffiniert» subtleties.

    Update: Changed wording because probably to harsh.

    «The Crux of the Biscuit is the Apostrophe»

    perl -MCrypt::CBC -E 'say Crypt::CBC->new(-key=>'kgb',-cipher=>"Blowfish")->decrypt_hex($ENV{KARL});'Help

      Thanks for comparing me with Joseph Goebbels, again!

      You must know, unfortunately I'm not old enough to tell ...

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery

        No, i didn’t. Please see the Duden and the Pons for further explanations. The adjective isn’t a genuine invention of Herbert Wehner related to Joseph Goebbels. Best regards, Karl

        «The Crux of the Biscuit is the Apostrophe»

        perl -MCrypt::CBC -E 'say Crypt::CBC->new(-key=>'kgb',-cipher=>"Blowfish")->decrypt_hex($ENV{KARL});'Help

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