Re: Enum.one?/1 and Enum.one?/2

[jisaa...@gmail.com]

My feelings:

> It is not solving a complex problem. Can be written in a single line

> It is not solving a common problem. I don't think I've ever had to write an equivalent function.

So personally I am against having it in stdlib.

On Monday, October 5, 2015 at 11:27:06 AM UTC-7, Bryan Enders wrote:

I believe `one?` would be a useful Enum function. It exists in Ruby's Enumerable module. It invokes a given function for each item in the enumerable and returns true if exactly one invocation returns a truthy value. It returns false otherwise.

This function tests for uniqueness or singularity. Unlike other uniqueness queries, it is concerned with the satisfaction of some criteria (expressed in the function argument) instead of an item's identity.

I have implemented `Enum.one?/1` and `Enum.one?/2` in this branch. A discussion began in a related pull request.

It is useful in Ruby. Do you think it has a place in Elixir?

[Booker Bense]

I agree, however this does bring up an issue of utils that I think might be 

usefully used in Elixir. 

I should probably flesh this out in another message. 

- Booker C. Bense 

[Aleksei Magusev]

Following on what has been said in the linked issue, I do think we should not have had `Enum.sum/1` at first place.

[Booker Bense]

This would be a great addition to the Crutches project. 

https://github.com/mykewould/crutches

- Booker C. Bense