+ requires one or more arguments

[cympfh]

I require that

hcl> (+)
0

But this occurs an error. Likewise (*) must be 1.

[olleicua]

Sounds good to me. I've made some notes on the commit for your pull request: https://github.com/cympfh/hcl/commit/e4864ec5a93884702dd0241f3b077200cc49b051