NonEmptySeq

Given that we’re going to add some NonEmpty collections, it will be natural to wish we had a NonEmptySeq that could be used as source for creating / transforming between them.

I think we can ensure non-emptiness by using specific constructors:

• We can create from a single value, alternatively taking an additional normal seq as “tail”.
• We can define a closed range operator that return a NonEmptySeq |.., also ..| and |..| where the number besides the bar always exists in the range. Example 1|..3 -> NonEmptySeq [1;2;3], 1|..0 -> NonEmptySeq [1], 10|..|3 -> NonEmptySeq [3].
• As in NonEmptyList, we can define a builder that doesn’t allow the Zero method, for NonEmptySeq literals: nes {1;2;3}
• Finally, we can add some safe/unsafe constructors from regular sequences, by checking on Seq.isEmpty

Any thoughs?

[gusty]

Good point, then we don’t.

[gusty]

What do you mean with

In many instances we assume that the sequence has 1

From the above list, only in the case of a unsafe constructor we’ll be assuming.

Regarding your question:

Then there is the question about other types that has some sort of sequenceable or range behaviour?

We would simply follow the same rules as the .. operator, I mean require the same static members.