[TINKERPOP-2491] Improve consistency of the output of range() oriented steps

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 3.4.9
• Component/s: process
• Labels: breaking
• Assignee: Unassigned
• Reporter: Stephen Mallette
• Created: 15/Dec/20 17:49
• Updated: 13/Apr/22 10:26

Description

As pointed out here:

https://groups.google.com/g/gremlin-users/c/OvxKvvM8rXs/m/slnv6cWpBQAJ

there is an automatic List unfold with limit(local, 1) as in:

g.inject([1, 2, 3], [4]).limit(local, 3).toList() // [[1, 2, 3], [4]]
g.inject([1, 2, 3], [4]).limit(local, 2).toList() // [[1, 2], [4]]
g.inject([1, 2, 3], [4]).limit(local, 1).toList() // [1, 4] ??? - Expected [[1], [4]]
g.inject([1, 2, 3], [4]).limit(local, 0).toList() // [[], []] oh come on

In addition, `range()` and `tail()` are similarly affected:

gremlin> g.inject([1, 2, 3], [4]).tail(local, 1).toList()
==>3
==>4
gremlin> g.inject([1, 2, 3], [4]).range(local, 0, 1).toList()
==>1
==>4

Changing this is a fairly imposing breaking change in behavior. We could mitigate that with a strategy to support the old functionality if folks want to have that:

g.withStrategy(OldWayStrategy).inject([1, 2, 3], [4]).limit(local, 1)

would transform to:

g.inject([1, 2, 3], [4]).limit(local, 1).unfold()