Funs names in Erlang 17

Question

Erlang 17 was released. And according to Erlang OTP 17.0 has been released:

Funs can now be given names

No examples are given.

Any ideas how to assign names to funs in Erlang 17?

Answer 1

Joe Armstrong explains it in his blog post with an example.

1> F = fun F(0) -> 1; 
           F(N) -> N * F(N - 1) 
       end.
#Fun

Previously you have to pass in the function as one of the args for anonymous recursive calls. (Think of y-combinator).

1> F = fun(F, 0) -> 1;
          (F, N) -> N*F(F, N-1)
       end.
#Fun

Answer 2

Named funs are a implementation of EEP37 see the link for a detailed description and rationale.

Answer 3

This version doesn't need to pass in the function as one of the args:

1> Fac = fun(Num) -> Foo = fun(F, 0) -> 1; (F, N) when N > 0, is_integer(N) -> N * F(F, N -1) end, Foo(Foo, Num) end.