Head Normal Form


Head Normal Form

(theory, reduction)(HNF) A term describing a lambda expression whose top level is either a variable, a datavalue, a built-in function applied to too few arguments, or alambda abstraction whose body is not reducible. I.e. thetop level is neither a redex nor a lambda abstraction with areducible body.

An expression in HNF may contain redexes in argument postionswhereas a normal form may not.

Compare Weak Head Normal Form.