Inconsistencies between return values - filter/distinct vs drop-while/drop-until

[rwtolbert]

filter and distinct always return an array, regardless of input:

repl:3:> (distinct @[1 2 3 0 -4 2 3])
@[1 2 3 0 -4]
repl:4:> (filter pos? [1 2 3 0 -4 2 3])
@[1 2 3 2 3]
repl:10:> (distinct "bookkeeper")
@[98 111 107 101 112 114]

whereas drop-while and drop-until return either a tuple or string

repl:2:> (drop-until |(< $ 65) "foo123bar")
"123bar"
repl:3:> (drop-while pos? @[1 2 3 0 -4 2 3])
(0 -4 2 3)

seems like drop-while and drop-until should at least return an array when given an array.

[sogaiu]

For reference, it looks like the drop-* siblings used to return arrays and that changed here.

Found some PRs that might give some hints about the current state of things:

• Add take/drop. #154
• Take and drop #156

[primo-ppcg]

The only of these that seems out of place is

repl:10:> (distinct "bookkeeper")
@[98 111 107 101 112 114]

The result should probably be a buffer.

[sogaiu]

For reference, I went over what seemed like some relevant callables in boot.janet and made a summary about return types and how they might relate to input arguments.

---

return type varies based on type of input

in-place mutation of input argument

• sort - buffer, array, table
• sort-by - buffer, array, table (undocumented)
• reverse! - buffer, array, table (undocumented)

new value

• take - tuple, string, table (undocumented), or array
• take-while - tuple, string, table (undocumented), or array
• take-until - tuple, string, table (undocumented), or array
• drop - tuple, string, table (undocumented), struct (undocumented), or array
• drop-until - tuple, string, table (undocumented), struct (undocumented), or array (undocumented)
• drop-while - tuple, string, table (undocumented), struct (undocumented), or array (undocumented)
• reverse - array or buffer

return type does not vary based on type of input

new array

• sorted
• sorted-by
• accumulate
• accumulate2
• map
• mapcat
• filter
• keep
• keys
• values
• pairs
• partition-by
• interleave
• distinct
• flatten
• kvs
• interpose
• partition

in-place mutation of input argument into (array)

• flatten-into

non-negative integer

• count

new tuple

• juxt

new table

• invert
• zipcoll
• merge
• frequencies
• group-by
• from-pairs

returns in-place mutation of input argument tab (table)

• merge-into

return type not as formulaic

• reduce - returns in-place mutation of input argument init
• reduce2 - returns result of series of computations
• find-index - returns non-negative integer, nil, or input argument dflt
• find - returns value in input argument ind, nil, or input argument dflt
• index-of - returns key in input argument ind or input argument dflt