#summary Definition of higher-order functions.
#labels Glossary

= Higher Order Functions =

Higher-order functions are functions that either take a function as an argument or return a function as a result. 

The primitive higher-order functions that return new functions in Cat are [Quote quote] and [Compose compose]. These can be used in conjunction with the [Shufflers stack shuffling functions] to create any other function. 

Higher-order functions which accept one or more functions as arguments are often referred to as [Combinators combinators]. The primitive combinators are [Eval eval] and [Dip dip].