Types

• declaration

  typedef t n	C, C++, Pike
  type n is t	Ada
  type n ...	Pliant
  type n = t	Haskell, OCaml, Pascal, SML
  TYPE n = t	Modula-3
  using n = ...	C#
  data n = t	Haskell
  datatype n = t	SML
  newtype n = t	Haskell
  n = t	merd
  n : t	Beta
  (deftype n () 't)	Common Lisp

• annotation (or variable declaration)

  :	Ada, E, Eiffel, Modula-3, OCaml, SML
  ::	Dylan, Haskell, Mercury
  !!	merd
  t v	C, C#, C++, Java, Perl6, Pike, Pliant, YCP
  (declare (v t))	Common Lisp
  v :@ t	Beta

• cast

  upcast

  (t) e	C, C#, C++, Java, PHP
  t(e)	Ada, Pascal
  [t] e	Pike
  static_cast<t>(e)	C++
  e :> t	OCaml
  CAST(e as t)	SQL92
  typecast(e,t)	Matlab

  downcast (need runtime checking)

  (t) e	Java
  t(e)	Ada
  e : t	E
  [t] e	Pike
  dynamic_cast<t>(e)	C++
  e as t	C#
  v ?= e (38)	Eiffel
  NARROW(e, t)	Modula-3
  typecast(e,t)	Matlab

  computed conversion (calls an internal or a user-defined function)

  (t) e	C++, Pike
  [t] e	MSH
  t(e)	C++, Matlab
  e : t	E
  cast e t	Pliant
  expr cast t	Pliant
  make t e / to t e	Rebol

• mutability, constness

  type of a mutable value

  it is the default	Ada, C, C#, C++, Java, Matlab
  val x: T	Pascal
  T ref	OCaml, SML
  STRef a T	Haskell

  type of a constant value

  const T	C++, C99
  constant T	Ada
  const x: T	Pascal
  it is the default	Haskell, OCaml, SML

  special cases

  "readonly" fields (39)	C#
  "final" fields, parameters, local variables (39)	Java

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