Example
Erlang is a functional programming language. One of the features in a function programming language is handling functions as data (functional objects).
- Pass a function as an argument to another function.
- Return function as a result of a function.
- Hold functions in some data structure.
In Erlang those functions are called funs. Funs are anonymous functions.
1> Fun = fun(X) -> X*X end.
#Fun<erl_eval.6.52032458>
2> Fun(5).
25
Funs may also have several clauses.
3> AddOrMult = fun(add,X) -> X+X;
3> (mul,X) -> X*X
3> end.
#Fun<erl_eval.12.52032458>
4> AddOrMult(mul,5).
25
5> AddOrMult(add,5).
10
You may also use module functions as funs with the syntax: fun Module:Function/Arity.
For example, lets take the function max from lists module, which has arity 1.
6> Max = fun lists:max/1.
#Fun<lists.max.1>
7> Max([1,3,5,9,2]).
9
