Overview

Rosetta defines several type categories that include elemental, composite, function, constructed, and facet types. The first of these categories, the elemental types, defines types as collections of atomic values. Element literals provide a mechanism for specifying element values in a specification. All elemental types are subtypes of the element type and include numbers, boolean values and characters, infinite values, and the the bottom value.

The number type is the supertype of all definable number values. Subtypes of number include complex, real, integer, natural, and bit as well as specific subtypes to aid in constraining number values further for specification purposes. Number literals provide a mechanism for specifying number values in specifications.

The boolean type defines the two literal Boolean values true and false along with the traditional Boolean operations. Distinct from the bit type, the boolean type provides an abstract means for specifying logical sentences and for specifying conditional properties.

The character type defines a mechanism for specifying and manipulating Unicode values. Unicode is used throughout Rosetta to promote readable specifications and use of international character sets. The character literals provide a mechanism for defining Unicode values in a specification. The character type provides operations similar to those used in ASCII and Unicode character systems, allowing characters to be used in traditional ways.

4.1 The Boolean Type

Rosetta provides a Boolean type consisting of the values true and false