Value (computer Science)

Value (computer Science)

In computer science, a value is an expression which cannot be evaluated any further (a normal form). The members of a type are the values of that type. For example, the expression "1 + 2" is not a value as it can be reduced to the expression "3". This expression cannot be reduced any further (and is a member of the type Nat) and therefore is a value.

The "value of a variable" is given by the corresponding mapping in the environment. In languages with assignable variables it becomes necessary to distinguish between the R-value (or contents) and the L-value (or location) of a variable.

In declarative (high-level) languages, values have to be referentially transparent. This means that the resulting value is independent of the location in which a (sub-)expression needed to compute the value is stored. Only the contents of the location (the bits, whether they are 1 or 0) and their interpretation are significant.