Contrary to Perl 6 my approach is still compatible, because you can transform them back into standard Perl 5.

      ... until the first time you run into a precedence problem, for example with hash or list slices.

    Don't know what you mean ... all my examples were parenthesized so precedence problems shouldn't occur !?!

I mean exactly:

    Actually it's practically impossible to implement this with a simple code-filter,...

My point is that the proposed transformation rules are well-defined and backwards-compatible within perl5, contrary to perl6. One can always take code with new sigils and transform it back into normal sigils and parentheses to run it with an old perl 5 version.

The implementation of these rules with static code filters can of course only be - like I already said - an ersatz to demonstrate the concept. This is certainly not meant for production.

For the realisation: If it's not possible to extend the perl parser accordingly, a real macro system is needed (which is N° 8 on my wishlist) That means changing the code after compilation but before execution!

>In other words, you're arguing to add more syntax to Perl, syntax that's difficult to type, to make the simple cases easy

well I think most languages, including perl6, consider it easier that arrays are primarily references and only transformed into a list if it's indicated by a modifier.

Maybe I should express these transformation rules with plain words instead of code, to make them clearer:

  1. €arr is a scalar $arr which holds a array_ref
  2. €arr[][] can be dereferenced without any arrow-operator, that means is identical to $arr->[]->[].
  3. Dereferencing of €arr has higher precedence than transformation to an array:  @€arr[][] == @{€arr[][]}
  4. In situations where the parser wants an array to follow (*), e.g. forced by prototype (\@) , €arr is passed directly. That means push €arr,expr is identical to push @$arr,expr
I think all perl-experts (like you are), might think it's getting more complicated this way, but I bet most beginners will consider it much easier and experts will adapt easily. Because it's huffman-coded, the frequent use cases are getting much easier, and the others don't get more complicated! And IMHO anyway there is no need anymore to use @arr or %hash if one can seemlesly use references!

Cheers Rolf

(*) more precisely in these situations an @ has to follow but only the reference is passed.

In reply to Re^8: Two more Features Perl 5 Maybe Needs by LanX
in thread Five Features Perl 5 Needs Now by Arunbear

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