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Chapter 5 The Revised syntax

The revised syntax is an alternative syntax for OCaml. Its purpose is to be simpler, more regular, more logical than the normal syntax, and fix some problems which sometimes result in bugs not always easy to find. This syntax was named ``righteous'' instead of ``revised'' in previous versions.

This chapter presents the changes from OCaml to this syntax.

5.1 Phrases

• A simple semicolon ends the sentences, in structures and in signatures. The double semicolon is not a token. There is no ambiguity with the sequence, which has a special construction (see 5.2).
  
  
• The declaration of a global variable is introduced by the keyword ``value'', ``let'' being reserved to the construction ``let..in'':

  OCaml	Revised
  let x = 23;;	value x = 23;
  let x = 23 in x + 7;;	let x = 23 in x + 7;

  
  
  
• In interfaces, one must use ``value'', too, instead of ``val''.

  OCaml	Revised
  val x : int;;	value x : int;

5.2 Imperative constructions

• The sequence is introduced by the keyword ``do'' followed by ``{'' and terminated by ``}'' (it is possible to put a semicolon after the last expression):

  OCaml	Revised
  e1; e2; e3; e4	do { e1; e2; e3; e4 }

  
  
  
• The body of ``for'' and ``while'' has the same syntax:

  OCaml	Revised
  while e1 do	while e1 do {
  e2; e3; e4	e2; e3; e4
  done	}

5.3 Tuples and lists

• Parentheses are mandatory in tuples: