Perl 6
Perl Lookup Table: Revision 23

Index - Chapter 0:Intr, 1:Hist, 2:Design, 3:Var, 4:Op, 5:IO, 6:{}, 7:Sub, 8:OOP, 9:Rx - Appendix A:Index, B:Tables, C:Best of, D:Delta, E:Links




Variables

Twigils

, or secondary sigils. They follow after a $ (scalar), @ (array) or % (hash) primary sigil, and mark special namespaces or variables with special meanings and properties.

$foo . . . ordinary scoping (no twigil)
$.foo. . . object attribute public accessor
$!foo. . . object attribute private storage
$^foo . . self-declared formal positional parameter
$:foo . . .self-declared formal named parameter
$*foo . . .contextualizable global variable
$?foo . . .compiler hint variable
$=foo . . .pod variable
$<foo> . .match variable, short for $/<foo> or even $/{'foo'}
$~foo . . .the foo sublanguage seen by the parser at this lexical spot

Special Variables

$/ . . . . . . . . . last created match object of this block
$<...> . . . . . . alias to named capture, see Twigils above
$0 .. $9 . . . . . alias to positional capture (like in P5)
@(). . . . . . . . array that holds $0 .. $9 and rest and positional submatches
$! . . . . . . . . . error msg
-
$*ARGS . . . . . Arguments (Parameter) to a program (script), formerly @ARGV
$*IN . . . . . . . standard input handle (command line mostly)
$*OUT. . . . . . standard output (command line mostly)
$*ERR . . . . . . standard error output (command line mostly)
$*PERL . . . . . perl version running under
@*INC. . . . . . include pathes (but not for std library modules), formerly @INC
$*KERNEL. . . . operating system running under
$*PID . . . . . . ID of the running process,
$*GID . . . . . . real global ID of the running process owner, formerly @(
$*UID . . . . . . real user ID of the running process owner (user), formerly @<
$*EGID . . . . . effective global ID, formerly @)
$*EUID . . . . . effective user ID, formerly @>
$*ON_WARN . . , formerly $SIG{__WARN__}
$*ON_DIE . . . . , formerly $SIG{__DIE__}
%*ENV . . . . . . , formerly %ENV
$*CWD . . . Str . . current working directory
$*COMPILING . . . .
$*DEBUGGING . . . .
-
$?KERNEL . . . . for which operating System was this program compiled?
$?PERL . . . . . . SoftwarePackage # Which Perl am I compiled for?, $?PERL.version for formerly $^V $]
$?CLASS. . . . . current class
@?BLOCK . . . . reference to current block
$?LINE . . . . . . current line number
-
@=COMMENT . All the comment blocks in the file
$=DATA. . . . . data block handle (=begin DATA ... =end)
@=DATA . . . . Same as above, but array
-
$~MAIN . . . the current main language (e.g. Perl statements)
$~Q . . . . . .the current root of quoting language
$~Quasi . . . the current root of quasiquoting language
$~Regex . . .the current root of regex language
$~Trans . . . the current root of transliteration language
$~P5Regex . the current root of the Perl regex language

Object Types

Any scalar variable (arrays and hashes are just collections of scalars) can hold any type of data. Nevertheless Perl knows for many data types specific classes (known as data types) that can handle them.

Bit . . . . . Perl single bit (allows traits, aliasing, undef, etc.)
Int . . . . . Perl integer (allows Inf/NaN, arbitrary precision, etc.)
Str . . . . . Perl string (finite sequence of Unicode characters)
Num . . . . Perl floating point number
Complex . . Perl complex number
Bool . . . . Perl boolean
Exception . Perl exception
Code . . . . Base class for all executable objects
Block . . . . Executable objects that have lexical scopes
List . . . . . Lazy Perl list (composed of immutables and iterators)
Seq . . . . . Completely evaluated (hence immutable) sequence
Range . . . A pair of Ordered endpoints; generates immutables when iterated
Set . . . . . Unordered collection of values that allows no duplicates
Bag . . . . . Unordered collection of values that allows duplicates
Junction . . Single value that could be one of several alternatives
Pair . . . . . A single key-to-value association
Mapping . . Set of Pairs with no duplicate keys
Signature . .Function parameters (left-hand side of a binding)
Capture . . .Function call arguments (right-hand side of a binding)
Blob . . . . . An undifferentiated mass of bits

low level data types

This is more low level than the last table. These types are more meant to give the compiler optimizing hints.

int1
int2
int4
int8
int16
int32 (aka int on 32-bit machines)
int64 (aka int on 64-bit machines)
uint1 (aka bit)
uint2
uint4
uint8 (aka byte)
uint16
uint32
uint64
num32
num64 (aka num on most architectures)
num128
complex32
complex64 (aka complex on most architectures)
complex128
Str

Operators

Table of precedence

A . Level . . . . . . . . . . . . Examples
= . =========== . . . ==================
N . Terms . . . . . . . . . 42 3.14 "eek" qq["foo"] $x :!verbose @$array
L . Method postfix. . . . meth .+ .? .* .() .[] .{} .<> .«» .:: .= .^ .:
N . Autoincrement. . . . ++ --
R . Exponentiation. . . . **
L . Symbolic unary. . . . ! + - ~ ? | +^ ~^ ?^ ^
L . Multiplicative . . . . . * / % +& +< +> ~& ~< ~> ?& div mod
L . Additive . . . . . . . . + - +| +^ ~| ~^ ?| ?^
L . Replication. . . . . . . x xx
X . Concatenation . . . . ~
X . Junctive and . . . . . & also
X . Junctive or . . . . . . | ^
L . Named unary . . . . . sleep abs sin temp let
N . Nonchaining infix. . . but does <=> leg cmp .. ..^ ^.. ^..^
C . Chaining infix . . . . . != == < <= > >= eq ne lt le gt ge ~~ === eqv !eqv
X . Tight and. . . . . . . . &&
X . Tight or. . . . . . . . . || ^^ // min max
R . Conditional. . . . . . . ?? !! ff fff
R . Item assignment . . . = := ::= => += -= **= xx= .=
L . Loose unary . . . . . . true not
X . Comma operator . . . , p5=> :
X . List infix. . . . . . . . . Z minmax X X~ X* Xeqv ...
R . List prefix. . . . . . . . print push say die map substr ... + * any $ @
X . Loose and . . . . . . . and andthen
X . Loose or . . . . . . . . or xor orelse
X . Sequencer. . . . . . . <==, ==>, <<==, ==>>
N . Terminator. . . . . . . ; {...}, unless, extra ), ], }

  Assoc Meaning of $a ! $b ! $c
L left ($a ! $b) ! $c
R right $a ! ($b ! $c)
N non ILLEGAL
C chain ($a ! $b) and ($b ! $c)
X list infix:<!>($a; $b; $c)

Filetest Ops

:r . . . file is readable by effective uid/gid.
:w . . . file is writeable by effective uid/gid.
:x . . . file is executable by effective uid/gid.
:o . . . file is owned by effective uid.
.
:R . . . file is readable by real uid/gid.
:W . . . file is writeable by real uid/gid.
:X . . . file is executable by real uid/gid.
:O . . . file is owned by real uid.
.
:e . . . file exists
:z . . . file has size equal to 0 (an empty file).
:s . . . file has size greater than 0 (returns size in bytes)
.
:f . . . file is a plain file.
:d . . . file is a directory.
:l . . . file is a symbolic link.
:p . . . file is a named pipe (FIFO), or filehandle is a pipe.
:S . . . file is a socket.
:b . . . file is a block special file.
:c . . . file is a character special file.
:t . . . filehandle is opened to a tty.
.
:u . . . file has setuid bit set.
:g . . . file has setgid bit set.
:k . . . file has sticky bit set.
.
:T . . . file is an ASCII text file (heuristic guess).
:B . . . file is a binary data file (opposite of :T).
.
:M . . . Script start time minus file modification time, in days.
:A . . . Same for access time.
:C . . . Same for inode change time (Unix, may differ for other platforms)

Metaoperators

They appear mostly before regular operators and give them different meaning or greater range.
In the example V stands for Value, L for left Value, and R for right. A number is the array index.

<op>= . . . self assign . . . known from P5, <var1> =<op> <var2> equals <var1> = <var1> <op> <var2>
>><op> . . hyper . . . processes arrays in parallel or applies a single value to all array elements; @E = L1 op R1, L2 op R2, ...;
<<<op> . . hyper . . . processes arrays in parallel or applies a single value to all array elements; @E = L1 op R1, L2 op R2, ...;<br />
[<op>]. . . reduction . . applies the operator between all elements of an array; $result = V1 op V2 op ...;<br />
[\<op>] . . reduction . . . applies above reduction to a series of lists made of array slices ranging in length from 1 to the complete length of the original list; @result = V1, V1 op V2, V1 op V2 op V3, ...;<br />
R<op> . . . reverse . . . reverses the operator<br />
X<op> . . . combinator . . .performs the operator to all the pairs of the Cartesian product of two arrays; @result = L1 op R1, L1 op R2, L2 op R1, L2 op R2 }}

Unicode operators

The two hyper operators can be written with the Unicode "chevron" signs (also documented as "French Quotes") or with double less than or greater than signs (documented as "Texas Quotes").

« aka <<
» aka >>

Smartmatch

$_ X Type of Match Wanted What to use on the right
Array Num array element truth .X
Array Num array contains number ,X,
Array Str array contains string ,X,
Array Seq array begins with seq X,*
Array Seq array contains seq ,X,
Array Seq array ends with seq *,X
Hash Str hash element truth .{X}
Hash Str hash key existence .{X}:exists
Hash Num hash element truth .{X}
Hash Num hash key existence .{X}:exists
Buf Int buffer contains int .match(X)
Str Char string contains char .match(X)
Str Str string contains string .match(X)
Array Scalar array contains item .any === X
Str Array array contains string X.any
Num Array array contains number X.any
Scalar Array array contains object X.any
Hash Array hash slice exists .{X.all}:exists .{X.any}:exists
Set Set subset relation .{X}:exists
Set Hash subset relation .{X}:exists
Any Set subset relation .Set.{X}:exists
Any Hash subset relation .Set.{X}:exists
Any Set superset relation X.{$_}:exists
Any Hash superset relation X.{$_}:exists
Any Set sets intersect .{X.any}:exists
Set Array subset relation X,* # (conjectured)
Array Regex match array as string .Cat.match(X); cat(@$_).match(X)

Quoting Ops and Adverbs

Short Long Meaning
:x :exec Execute as command and return results
:w :words Split result on words (no quote protection)
:ww :quotewords Split result on words (with quote protection)
:q :single Interpolate \\, \q and \' (or whatever)
:qq :double Interpolate with :s, :a, :h, :f, :c, :b
:s :scalar Interpolate $ vars
:a :array Interpolate @ vars
:h :hash Interpolate % vars
:f :function Interpolate & calls
:c :closure Interpolate {...} expressions
:b :backslash Interpolate \n, \t, etc. (implies :q at least)
:to :heredoc Parse result as heredoc terminator
  :regex Parse as regex
  :subst Parse as substitution
  :trans Parse as transliteration
  :code Quasiquoting

Text Processing

Escape Sequence

Make control chars when used in a double quoted string.

\a . . . . . . . . BELL
\b . . . . . . . . BACKSPACE
\e . . . . . . . . ESCAPE
\f . . . . . . . . FORM FEED
\n . . . . . . . . LINE FEED
\r . . . . . . . . CARRIAGE RETURN
\t . . . . . . . . TAB

Rule primitives

\0[ . . . ] Match a character given in octal (brackets optional).
\b Match a word boundary.
\B Match when not on a word boundary.
\c[ . . . ] Match a named character or control character.
\C[ . . . ] Match any character except the bracketed named or control character.
\d Match a digit.
\D Match a nondigit.
\e Match an escape character.
\E Match anything but an escape character.
\f Match the form feed character.
\F Match anything but a form feed.
\n Match a (logical) newline.
\N Match anything but a (logical) newline.
\h Match horizontal whitespace.
\H Match anything but horizontal whitespace.
\L[ . . . ] Everything within the brackets is lowercase.
\Q[ . . . ] All metacharacters within the brackets match as literal characters.
\r Match a return.
\R Match anything but a return.
\s Match any whitespace character.
\S Match anything but whitespace.
\t Match a tab.
\T Match anything but a tab.
\U[ . . . ] Everything within the brackets is uppercase.
\v Match vertical whitespace.
\V Match anything but vertical whitespace.
\w Match a word character (Unicode alphanumeric plus "_").
\W Match anything but a word character.
\x[ . . . ] Match a character given in hexadecimal (brackets optional).
\X[ . . . ] Match anything but the character given in hexadecimal (brackets optional).

Flow Control

Closure Traits

in every block can be inserted several special named blocks that are started at certain times. Because they are treated as part of a block object, they are called traits. Those marked with a * can also be used within an expression.

BEGIN {...}* at compile time, ASAP, only ever runs once
CHECK {...}* at compile time, ALAP, only ever runs once

INIT {...}* at run time, ASAP, only ever runs once
END {...} at run time, ALAP, only ever runs once

START {...}* on first ever execution, once per closure clone
ENTER {...}* at every block entry time, repeats on loop blocks.
LEAVE {...} at every block exit time
KEEP {...} at every successful block exit, part of LEAVE queue
UNDO {...} at every unsuccessful block exit, part of LEAVE queue

FIRST {...}* at loop initialization time, before any ENTER
NEXT {...} at loop continuation time, before any LEAVE
LAST {...} at loop termination time, after any LEAVE

PRE {...} assert precondition at every block entry, before ENTER
POST {...} assert postcondition at every block exit, after LEAVE

CATCH {...} catch exceptions, before LEAVE
CONTROL {...} catch control exceptions, before LEAVE


Index - Chapter 0:Intr, 1:Hist, 2:Design, 3:Var, 4:Op, 5:IO, 6:{}, 7:Sub, 8:OOP, 9:Rx - Appendix A:Index, B:Tables, C:Best of, D:Delta, E:Links



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