Kermeta implements a few primitive types. By primitive types, we mean types that are basic to any language, i.e integer, and that have a literal value. See below table.

// Simple datatypes examples
var myVar1 : Integer init 10
var myVar2 : Integer
var myVar4 : String init "a new string value"
var myVar5 : boolean

Kermeta also supports some other primitive types like Float and Character, but they currently don't have a surface syntax for their literals. The way to get them is to use the convertion methods available on String (for both of them) or Integer (for Float).

For example:

var c : Character init "f".elementAt(0)
var r : Real init "4.5".toReal

You can define enumerations using the following syntax. Note that each enumeration literal must end with a ";".

enumeration Size { small; normal; big; huge; } 

You can manipulate enumerated variables and literals with classical operators such as in the following example.

var mySize : Size
if ( mySize == Size.small ) then 
    stdio.writeln("This is small !") 
end

In Kermeta, you can define your own datatype based on existing types without a hard dependency like inheritance.

This is done using the alias syntax.

Ex:

alias MyString : kermeta::standard::String;

In this sample, MyString has all the behavior of kermeta::standard::String but is declared locally. This means that you don't have any dependency to the framework, even to the String in the framework.

Obviously you can reuse existing type names :

alias String : kermeta::standard::String;

This will create a new type String in your package with the behavior of String in the framework.

The definition of an alias is different from the use of "using" statement (as defined in Section 2.14, “ using keyword syntactic sugar ” ), when you write

using kermeta::standard

you simply defined a syntactical shortcut allowing you to access any definition in this package from within this file.

Wheras defining an alias allows you to access this new definition from another package if needed.