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🦪 Perl

Perl6 offers an interactive shell, but previous versions needed a specialized command to be run through the interpreter

General syntax - Semicolons terminate lines - Whitespace is irrelevant, except inside strings - Enclosing function arguments in parentheses is optional

Inline execution of code

Compare similar syntax for sed (MP:17, YUG:614) 

perl6 -e 'code'
Enable warning messages 
perl6 -w
Request an implicit input-reading loop that stores records in $_ 
perl6 -n
Request an implicit input-reading loop that stores records in $_ and automatically prints that variable after optional processing of its contents 
perl6 -p

-l :automatically insert an output record separator at end of the output of print

-0digits
define the character that marks the end of an input record, using octal digits

Shebang 

#!/usr/bin/env perl`

Perl variables are of three types, associated with 3 corresponding sigils which begin the identifiers - Scalars: $ - Arrays: @ - Hashes (associative arrays): %

my declares and initializes a variable. Variables can be typed by placing a type between my and the identifier. 

my $animal = "camel"
my Str $animal = "camel"

Predefined variables 

$.    # current line number
$_    # conventionally used as a default pattern space for searches; is already initialized but not defined; does **not** function like in bash
$[    # current array base subscript (0 by default)
$/    # input line separator (newline by default)
@ARGV # arguments passed from the command-line; index 0 is the first **additional** argument passed subsequent to the name of the script

Sources:

Scalar

Operations

$pbj = 'peanut butter'.' and '.'jelly'
string concatenation was performed with . operator in Perl5 (YUG:617)
$pbj = 'peanut butter'~' and '~'jelly'
string concatenation now performed with ~ operator in Perl6
print '*' x 40
x operator repeats the string (YUG:617)

Array

my @array = (element, element, element) | my @array = element, element, elmeent
initialize arrays by (optionally) enclosing elements in parentheses (not brackets)
@array[n]
retrieve element at (0-based) index {n}
$matrix[0]->[0]
arrow or infix operator can also be used to dereference array refrences
$#array
return number of the last subscript in the array (effectively length-1)
@colors=('red','green','yellow','orange');
($c[0], $c[1], $c[3], $c[5]) = @colors;
arrays can be declared by initializing constituent elements (array slicing) (PBX:85)

Operations

@list=(2..10);
assign a range of numbers (arr-rng) (PBX:81)
@letters=( 'A' .. 'Z' );
assign a range of letters (PBX:82)
my @biglist = |@smalllist, |@littlelist
array unpacking is done using the | prefix operator, allowing for concatenation

Hash

Hashes are key-value pairs
my %fruits = (apple => red, ...)
declare a hash
%fruits{'apple'}
values are obtained by referencing the key in curly braces (vice brackets) (p6)

Functions

defined
return 1 if the variable passed as argument has a value and null if it does not
die mesg
print {mesg} and exit; used to implement error-handling

join (YUG...)

print
print to STDOUT, but with no ending string specified
prompt
take input from STDIN
read filehandle, variable, n
read {n} bytes into {variable} from {filehandle} (deprecated in Perl6) (PBX:96)
say
print to STDOUT, but with a newline at the end (Perl6)
undef
undefine a defined variable, releasing the memory allocated for it

Arrays

pop @array
remove and return last element of {array}
push @array, elements
append {elements} to {array}
shift @array
remove and return first element of {array}
splice @array, index, n[, elements]
remove {n} {elements} from {array}, starting at {index}; or, add {elements} to {array} at {index}
unshift @array, elements
prepend elements to an array (on the left side)

Strings

chomp
remove last character from a scalar or last character from each word in an array if and only if that character is the input line separator
chop
remove last character from a scalar or last character from each word in an array; intended for use in removing newlines
s/pattern/substitution/g ;
substitution command works similar to sed
tr/regex1/regex2/ ;
replace instances of {regex1} with {regex2}; like replacing lowercase letters with uppercase

split /delim/

Hashes

keys(%hash) ;
return an array of the keys of {hash}
values(%hash) ;
return an array of the values of {hash}

Filehandles

<>
null filehandle (YUG:618)
INFILE
filehandle used when opening a file for input (YUG:632)
OUTFILE
filehandle used when opening a file for writing
STDIN
deprecated in Perl6 (PBX:96)

Special literals

These have been deprecated in Perl6 (PBX:51)

__LINE__ (Perl5) | $?LINE (Perl6)
current line number
__FILE__ (Perl5) | $?FILE (Perl6)
current filename
__END__
logical end of the script (\004 in Unix and \032 in Windows)
__DATA__
special filehandle
__PACKAGE__ (Perl5) | $?PACKAGE (Perl6)
current package; default package is main

Control flow

Loops

for @array { action } | deprecated: foreach $var (@arr) { statements}
foreach loops have been replaced by for in Perl6
for @array { .print } | deprecated: for @array { print }
here the print function is working as a method on $_, the default variable
for @array1 Z @array2
zip up elements of two separate arrays (Source)[https://perl6advent.wordpress.com/2009/12/07/day-7-looping-for-fun-and-profit/]

Documentation

Implemented using markup language called "pod", which uses directives distinguishable by the = character

=begin pod
start documentation
=end pod
end documentation

Glossary

lvalue
any value that can be "assigned to", and which represents a named region of storage (PBX:71)
array slice
when the elements of one array are assigned values from another (PBX:84)

Object-oriented programming

instance variables declared with has keyword: has $.name; class attributes are declard with my keyword, then a method is declared to allow it to be referenced

Math

Mathematical consonants have their own keywords in Perl6: pi, e, and tau (2*pi)

Other topics

rename function in Debian

The Rename Command

Visual Basic

VB script doing manual backup 

On Error Resume Next 
Set objNetwork = WScript.CreateObject("WScript.Network")
objNetwork.RemoveNetworkDrive "P:"
objNetwork.MapNetworkDrive "P:", "\\islfs02.hlm.ad.moffitt.usf.edu\research\lab_proteomics",, "hlm\proteomics_backup","orbitrap"

Dim WSHShell
Set WSHShell = WScript.CreateObject("WScript.Shell")
q = """"
sp = " "

from = q & "c:\xcalibur\Data\*.*" & q
dest = sp & q & "p:\backup\QE_FOCUS\data" & q
cmd = "c:\windows\system32\xcopy " & from & dest & " /D /H /E /C /K /R /Y /I"
WSHShell.Run cmd, 1, true

from = q & "c:\xcalibur\methods\*.*" & q
dest = sp & q & "p:\backup\QE_FOCUS\methods" & q
cmd = "c:\windows\system32\xcopy " & from & dest & " /D /H /E /C /K /R /Y /I"
WSHShell.Run cmd, 1, true

Set WSHShell = Nothing
WScript.Quit(0)