throwway120385 8 hours ago

The variable prefixes are just the tip of the iceberg. The real problem with those prefixes is that they, themselves, are context-dependent on attributes associated with the underlying data type at run time. So you can find yourself in a situation where the behavior of the syntax differs in ways that are difficult to control for during development.

▲ zbentley 5 hours ago | parent | next [-]

Strongly agree. A language which has something like “wantarray” as a first-class feature is semantically…unique, at best, probably more like “flawed by design”. All the oddness with typing and sigls descends from that.

Same for autovivification. Insane feature. Useful for some problems but causes many more.

Which is a shame, because perl5 semantics had some nice features too! But there’s only so much you can do with a structure whose foundation is so wacky.

▲ karel-3d 3 hours ago | parent | next [-]

You unlocked hidden memories within me.

I never understood why Perl has all these crazy features. It feels like someone going "hah it would be funny if it worked like this..." but actually really implementing it.

People always said "it's because Larry Wall is a linguist!" as if it explains anything!

You always go from "this is neat" to "...but why" quickly with perl.

▲ zahlman 4 hours ago | parent | prev [-]

I remember trying to use the new "reference" feature (when it was new), with "blessing" and so on and so forth, to try to create real data structures, and finding in some way or another that it was just not regular. I can't recall the details, but something along the lines of a feeling that the syntax worked differently for, say, the top level of a tree (or first index of a multidimensional array, etc.) vs the rest of the structure.

▲ darrenf 3 hours ago | parent [-]

In the main, the sigil refers to the type of the eventual value, regardless of what contains it. The tl;dr is that you mostly use `$` unless you're wanting more than one value, or to dereference (when you use the sigil for the type of reference). Some examples:

    @array = ("a", "b", "c", "d"); # @array contains scalars
    $array[0];                     # use `$` for a single element
    @array[0..2];                  # use `@` for an array slice
    @array = ( [1..5], [6..10] );  # @array now contains array references
    $array[0];                     # use `$` still because references are scalars
    $array[0][1];                  # still use `$` even when going multidimensional
    @{ $array[0] };                # use `@` to dereference an array ref to array
    %hash = ( a => "b", c => "d"); # % for hash of key/value pairs
    $hash{a};                      # `$` because you're getting a single scalar
    @hash{"a","c"};                # `@` because you're getting an array of values

Where things become a bit less regular is the difference between reference and non-reference for hashes and arrays when they are top level. At the top level, you need a `->` but that becomes optional at levels below (because at levels below, they have to be references).

    $arrayref = [1,1,2,3,5];       # `$` because we're creating an array reference
    $arrayref->[0];                # `->` because top level
    $arrayref = [ [ 1 ], [ 2 ] ];  # arrayref of arrayrefs
    $arrayref->[0][0];             # no second `->`
    $arrayref->[0]->[0];           # ... but you can use it if you want!

And then there's stuff like getting a slice out of an arrayref

    $arrayref = [1,1,2,3,5];
    $arrayref->@[0..3]; # oh dear. get a real array with an `@` but not at the start!

So... yeah.

	▲	zahlman 2 hours ago \| parent [-]
		> Where things become a bit less regular is the difference between reference and non-reference for hashes and arrays when they are top level. At the top level, you need a `->` but that becomes optional at levels below Yes, that's probably what I was remembering. Thanks for the exposition.

▲ mono442 8 hours ago | parent | prev [-]

Yep, there're all sorts of things like this in Perl. Its semantics has always been confusing to me.