Editing Lithe (section)

==Examples==
Programming in Lithe consists of defining rule-action pairs and classes. Take the task of computing the [[absolute value]] of a number, for example:

 '''rule''' "|" &lt;i:'''int'''> "|" '''return int''';
   {'''if''' i<0 '''then return''' -i '''else return''' i '''end'''}

After this rule-action pair has been defined, it can be freely used within Lithe source code, for example, the following expression will thereafter be valid:

 |x - y| + 3

The equivalent rule in [[Backus–Naur form|BNF]] would be:

 &lt;'''int'''>  ::=  "|" <'''int'''> "|"

Note that the Lithe description swaps the left and right sides of the BNF one, then adds a name to each nonterminal in the BNF right-hand side. These names are used in the action part, which is expressed as a string that is translated into a sequence of actions by using other, previously defined, rule-action pairs (eventually, some of those rule-action pairs will invoke primitive actions).