Booleans

• type name

  Bool	Haskell, Perl6, Pliant
  bool	C#, C++, C99, OCaml, Python, YAML
  Boolean	Ada, Lua, Pascal, Smalltalk, Visual Basic
  boolean	Common Lisp, Java, Maple, YCP
  BOOLEAN	Eiffel
  logic!	Rebol
  logical	Matlab

• false value

  nil	Common Lisp, Emacs Lisp, Lua
  undef / 0 / "0" / "" / ()	Perl, Perl6
  False / None / 0 / "" / () / [] / {}	Python
  false / 0 / ""	PHP
  NULL / 0 / '\0'	C
  NULL / 0 / '\0' / false	C++, C99
  0 / "0" / ""	Awk
  0 / NaN / "" / false()	XPath
  0	Classic REXX, MUMPS
  0 (63)	B, Pike
  0 / False	Visual Basic
  0 / 0.0 / [] / {} / '' / false / array containing at least one false value	Matlab
  false / none	Rebol
  false / null / undefined / 0 / NaN / ""	JavaScript
  false / no / off / 0	Tcl
  false / no / off / n	YAML
  false / nil	Lua, Ruby
  false	Ada, BCPL, Beta, C#, E, FL, Java, Logo, OCaml, Oz, Pascal, Pliant, PostScript, Smalltalk, SML, YCP
  False	Eiffel, Haskell, merd
  FALSE	Modula-3, SQL92
  false / exit status different from 0	sh
  false / FAIL	Maple
  No / fail	Prolog
  #f	Dylan, Scheme

• true value

  anything not false	Awk, B, C, Matlab, Perl, Perl6, Pike
  true / anything not false	C++, C99, JavaScript, Lua, PHP, Ruby
  true / anything not false	Rebol
  True / anything not false	Python
  true() / anything not false	XPath
  #t / anything not false	Dylan, Scheme
  t / anything not false	Common Lisp, Emacs Lisp
  1 / anything not false	MUMPS
  yes / on / true / non zero number	Tcl
  yes / on / true / y	YAML
  True	Eiffel, Haskell, merd
  non-zero-numbers / True	Visual Basic
  TRUE	Modula-3, SQL92
  true	Ada, BCPL, Beta, C#, E, FL, Java, Logo, Maple, OCaml, Oz, Pascal, PHP, Pliant, PostScript, Smalltalk, SML, YCP
  true / exit status 0	sh
  Yes / true	Prolog
  1	Classic REXX

• logical not

  !	Awk, B, C, C#, C++, E, Java, JavaScript, Perl, Perl6, PHP, Pike, Ruby, Tcl, YCP
  not	Ada, Beta, Common Lisp, Eiffel, Emacs Lisp, Forth, Haskell, Logo, Lua, Maple, merd, OCaml, Pascal, Perl, Perl6, Pliant, PostScript, Prolog, Python, Rebol, Ruby, Scheme, Smalltalk, SML, XPath
  Not	Oz, Visual Basic
  NOT	Modula-3
  ~	BCPL, Dylan, Matlab, PL/I
  ^	PL/I
  '	MUMPS
  \	Classic REXX

• logical or / and

  short circuit

  || / &&	Awk, C, C#, C++, E, Haskell, Java, JavaScript, Matlab, merd, OCaml, Perl, Perl6, PHP, Pike, Ruby, Tcl, YCP
  | / &	B, BCPL, Dylan
  or / and	Common Lisp, Emacs Lisp, Logo, Lua, Maple, Modula-2, Perl, Perl6, PHP, Pliant, Python, Ruby, Scheme, Smalltalk
  or / &	OCaml
  or / and & (64)	Modula-2
  OR / AND	Modula-3
  any / all	Rebol
  orelse / andalso	SML
  orelse / andthen	Oz
  or else / and then	Ada, Eiffel
  ; / ,	Prolog
  & / !	MUMPS

  non short circuit (always evaluates both arguments)

  | / &	C#, Classic REXX, Java, Matlab, Smalltalk
  or / and	Ada, Beta, Eiffel, Forth, Pascal, PostScript, Rebol, SML, XPath
  Or / And	Visual Basic
  Or / And (65)	Oz
  \/ / /\ (10)	BCPL
  ?| /	Perl6

Remarks

• (1) for C, it is not a standard convention, but it is the more widespread
• (2) any string literal would work
• (3) see also =head1, =head2, =over, etc
• (4) need "file: %script-header.r" in file header
• (5) displayed <- with a special character
• (6) variable on the right
• (7) the variable behaves like a pointer
• (8) cf horizontal layout
• (9) introduce scope
• (10) ascii representation, original uses a special charset
• (11) <> and # are synonyms
• (12) === and !== differ from == and != when the objects' type differ
• (13) for objects
• (14) normal / structural / unification / arithmetic
• (15) deep comparison
• (16) in List::Util
• (17) Univ operator
• (18) procedure call
• (19) the function is "f: g:"
• (20) special sugar for only one parameter
• (21) there really is a parameter which is the empty tuple
• (22) f is a block
• (23) when callee has special "&" prototype
• (24) this is a block, not precisely a function, but it's alike
• (25) also works for procedures: proc {$ A B} ... end
• (26) x, y, z are the parameters
• (27) method is optional
• (28) in Lua, "return xxx" can only appear before a block end
• (29) only in inline('...')
• (30) "return" is used when there is no value to return
• (31) only for anonymous function
• (32) the result goes to "e"
• (33) "break"s are mandatory, even for "default"!
• (34) Perl >= 5.8.0
• (35) cond
• (36) see also catch/throw
• (37) often provided in the abbreviated form call/cc
• (38) expression "e" is cast to the type of "v"
• (39) quite bad: only the reference is non-mutable whereas the object is still mutable
• (40) eventual send
• (41) properties are something alike attributes, but really are methods
• (42) one level depth
• (43) general deep copy function
• (44) object cloning is the default, uses the copy constructor in C++
• (45) assignment attempt
• (46) does not work on builtin types
• (47) see also callable(obj.meth) for unbound methods
• (48) usually called self
• (49) ":" is for external symbols only, recommended
• (50) directory name is package name
• (51) if names are exported using @EXPORT
• (52) if names are not exported or are exported using @EXPORT_OK
• (53) deprecated in ANSI Common Lisp, but used in ASDF
• (54) using a correspondance from the package name to the file name
• (55) when using format
• (56) but not using the C-like %-syntax
• (57) adding an end-of-line
• (58) adding an end-of-line unless already newline-terminated
• (59) faster than isEqual
• (60) Lua 5.0
• (61) is range-checked whereas a[i] is not
• (62) ESI dialect
• (63) beware of 0.0 which is true in Pike!
• (64) &, and synonyms
• (65) simple functions, not operators