Question about function type constructor explain

[neighborhood999]

In Function type constructor second explain：

The syntax is: () -> , where comprises zero or more comma–space (,)-separated type representations and parens may be omitted for unary functions.

Sorry, I'm not a native in English so I feel confuse, Is parens means parents? Thanks!

[davidchambers]

Thank you for raising this issue, @neighborhood999. I'm sorry that the wording is unclear. Parens is another way of writing parentheses, the plural form of parenthesis.

The quoted sentence states that although one could write (a) -> b, for a function with exactly one parameter it's okay to write a -> b instead (without parens).

I hope this is clearer now. :)

[neighborhood999]

@davidchambers Thanks for your explain, It's clear to me!