Dictionary.net

Any relational language or functional language.These kinds of programming language describe relationshipsbetween variables in terms of functions or inferencerules, and the language executor (interpreter orcompiler) applies some fixed algorithm to these relationsto produce a result.Declarative languages contrast with imperative languageswhich specify explicit manipulation of the computer's internalstate; or procedural languages which specify an explicitsequence of steps to follow.The most common examples of declarative languages are logicprogramming languages such as Prolog and functionallanguages like Haskell.See also production system.