1627 replace seq

[jaapterwoerds]

As suggested in #1627, I replaced the usage of Seq by IList.

[tonymorris]

👍

It might also be worth writing a document making it clear why Seq has no use-cases.

[hrhino]

Would it make sense to replace some of those with arbitrary Foldable/Traversable types? An IList is O(n) to construct if you happen to only have a Foldable lying around.

[jaapterwoerds]

@tonymorris Good point, but I'm not sure where this would fit in the project and or if it it should be part of this PR. I am for giving the good example in the Scalaz code base and example and test and remove undesirable structures further.

@hrhino I will take a look to see if I use the abstraction instead of concrete IList some cases.

[emilypi]

👍

[tonymorris]

@jaapterwoerds yeah not in this PR. Perhaps open an issue for creating a document that specifies "the useful subset of scala" so that others can see it, and understand some of the reasoning.

Just a suggestion.

[hrhino]

FWIW just this week I wanted to ISet.unions an ISet of ISets. (Obviously it can't make a Monad so flatMap in general was out.) Making an IList of it would have been wasteful.

[fommil]

are we good to merge?

[jaapterwoerds]

@hrhino I've spent some time trying to figure out if I could replace IList by Foldable or Traversable but could not find any way.

@fommil I don't have anything else to add so we're good AFAICS