seq return iterable

[brandonstubbs]

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This PR is addressing issue #92 and discussion #109

[borkdude]

Can you mention the issue in the original message?

[brandonstubbs]

I have done the following changes:

seqable?

Before the following cases would fail:

(seqable? {:a 1})
(seqable? 1)
(seqable? true)

As per our discussion, you can be seqable if you are one of the following:

1. You implement the Symbol.iterator protocol
2. You're a POJO
3. You're nil

I have done the changes to just deal with the base types, as null and Symbol.iterator are object types

NOTE: cases such as new Boolean(true) would have and still will fail (as these are object types and not their primitives), we can add fine-grained checking if we think we need to handle these scenarios. What do you think?

iterable

iterable still returns an iterable even if it's empty. However, now there is a change that it will return undefined if there is a a type that can not be an iterable such as a boolean or number.

seq

Now throws if the coll is not iterable.

es6_iterator

calls seq internally but it will return an iterable even if the collection is empty. Functions that were using iterable before should now use es6_iterator as this is safe to destructure. It also gives the same behaviour clojurescript would for cases such as (first 1) or (map identity 1)

Let me know your thoughts on this and if you are happy I will update the documentation accordingly.

cc @lilactown

[borkdude]

I'm closing this for now as I'd like to only keep things open that are worked on. Feel free to re-open as necessary.