stateless. A stateless server is one which treats each request as an independent transaction, unrelated to any previous request. This simplifies the server design because it does not need to allocate storage to deal with conversations in progress or worry about freeing it if a client dies in mid-transaction.
An expression in a programming language is a combination of one or more explicit values, constants, variables, operators, and functions that the programming language interprets (according to its particular rules of precedence and of association) and computes to produce (to return, in a stateful environment) another value.
In functional programming, the resulting values are often functions or expressions, which can themselves be further evaluated. For example, 2+3 is an arithmetic and programming expression which evaluates to 5. A variable is an expression because it denotes a value in memory, so y+6 is an expression. An example of a relational expression is 4â 4, which evaluates to false.