Intro - Chapter: 0:History 1:Design 2:Basics 3:Var 4:Op 5:IO 6:Block 7:Sub 8:OOP 9:Rx 10:Meta
Overview - Appendix: A:Index B:Tables C:Cook D:Delta E:Best of F:Links G:Glossary

Trends

Ubiquity

As always, Perl is optimized for freedom and richness of expression.

General Purpose

Perl 5 still has a lot of builtins, showing for which task the language was created. But to become more general purpose, the core was enhanced and some other parts got removed. File IO, Network and IPC, Formats, and finally that long deprecated pre P5 DB-binding (dbmopen) went out of the core or at least into sensible module namespace. The optional type system enables compiler optimisations to make Perl even usable in cases where you had to switch to C before.

Less Unix Centric

Perl 1 was a child of the Unix world, borrowing a lot of folklore and words. As Perl 6 had to regularize the Regex and reform some other parts, this heritage has become less visible.

Unicode

Per default all Perl 6 code is Unicode and you can use any weird character for any part of the syntax.

Simple English

In Perl 5 we had my, our, use, require, bless, can, ISA (is a), chop and also of course if, else, goto and all the loops. Perl 6 adds given, when, gather, take, loop, WHERE, HOW, WHO and lot more everyday English, which should make it easy to read and understand.

Hidden Complexity

Even simple Perl 6 looks pretty much like older Perl, it has a tremendous complexity inside, which only have to show up if you really need it.

Functional Programming

High order functions, currying, you name it. All that goodies are there, as Perl 6 aims to a full support of functional programming.

Object Oriented

OOP syntax is now more simplified, compact, knows about encapsulation and has many new features, including dynamic class composition.

Like in Smalltalk or Ruby every "thing" (values, vars, blocks, routines) is an object and ops are "just" methods. It helps to have internally everything in its place. But programmer still can pretend it's not the case.

Full Introspection

Because every object knows his attributes and methods, you can ask the compiler nearly anything about the state of your program.

Metalanguage

And because classes are made to get extended or changed, Perl 6 has not only full metaprogramming capabilities, beyond your wildest dreams. It is a metalanguage with a beginner friendly default that aims to become a family of languages. Rule of thumb: everything is allowed, as long as you declare it.

One Spec - Many Implementations

Unlike every other Perl so far, Perl 6 has a precise specification, written in Perl 6. This allows to have several implementations, even syntactical compatible ones.

Syntactical Changes

• use strict and warnings and utf are on by default

Operator

• -> (arrow) becomes . (dot) - for method calls: object.method;
• =~ becomes ~~ - use regex now only with smartmatch
• qw( ... )(exists still) becomes < ... > - with interpolation and quote protection: << ... >>
• | becomes +| - logical bit operation in numerical context
• & becomes +&
• ^ becomes +^
• << becomes +< - shifting numerical values
• >> becomes +>
• . becomes ~ (tilde) - for concatenate strings: 'Shinmen Musahashi: ' ~ 'Sho Rin No Sho';
• .. becomes ff - flipflop operator
• ... becomes fff
• cmp becomes leg - cmp is now for general comparison, leg in string context
• ? : becomes ?? !! - ternary operator
• length becomes chars - number of chars in a string

Variable

• consistent sigils: so @array[1] replaces $array[1] and %hash{'key'} replaces $hash{'key'} and %hash{'key1', 'key2'} replaces @hash{'key1', 'key2'}
• scalar @a becomes +@a
• arrays, hashes, formats, directories and filehandles are internal objects with procedural Interfaces and can be saved in scalar variables.
• special variables have their own namespace ($*VARNAME and $?VARNAME), also token (__LINE__) will now be found there

Flow Control

• no more 'foreach'. 'for' now iterates only on arrays
• for ($a = 0; $a++; $a < 5) becomes loop ($a = 0; $a++; $a < 5)
• do {...} while (...); becomes repeat {...} while ...;

• define classes with 'class' and modules with 'module'
• no more source filters, but macros
• no more references, bind variables on the symbol table

Traps

• no more each, use .pairs or .kv instead
• no more C-style for, use loop instead
• length( @a) is now elems @a and length $str is chars $str;

News

• new contexts: hashlist, lazy list, bool, int, num, string
• optional typing, traits (properties of variables), binding
• loop and say commands
• zip, err, yadda and pipe operators
• hyper / reduction operators
• chained comparison operators
• case construct with given and when
• junctions : if $a = 1|2|3
• currying
• smartmatch / rules (regex++, own sublanguage within the language like in Rebol)
• named parameters for subroutines, multimethods, coroutines
• more explicit OOP:
• autogenerated getters/setters
• roles (similar to Ruby's Mixins, or Java's Interfaces)
• delegation, design by contract (Eiffel)
• exceptions, continuations
• macros

Native Perl 6 (new idioms)

• no parentheses required for control expressions after if, unless, while ... (but still allowed)
• %hash<key> instead of %hash{'key'}, or %hash<< key1 key2 >> instead of %hash{ 'key1', 'key2' }
• loop instead while (1)

For more native Perl 6, read the cookbook.

Intro - Chapter: 0:History 1:Design 2:Basics 3:Var 4:Op 5:IO 6:Block 7:Sub 8:OOP 9:Rx 10:Meta
Overview - Appendix: A:Index B:Tables C:Cook D:Delta E:Best of F:Links G:Glossary