[erlang-questions] Proposal: add lists:intersperse/2 and lists:intercalate/2

Dmitry Kolesnikov <>
Wed Mar 2 18:30:02 CET 2016


Hello,

“interleave” and “join” are friendly for non-native English programmers.   

Otherwise +1

- Dmitry

> On Mar 2, 2016, at 7:02 PM, Siraaj Khandkar <> wrote:
> 
> On 3/2/16 9:47 AM, Jesper Louis Andersen wrote:
>> Hi Erlangers,
>> 
>> I'd really like to add two functions to the lists module from Haskell:
>> 
>> intersperse(List, Seperator) produces a list where each element is
>> separated by separator, i.e.
>> 
>> X = [1,2,3]
>> [1, x, 2, x, 3] = lists:intersperse(X, x),
>> 
>> and it's cousin, intercalate(ListOfLists, Separator) is
>> append(intersperse(ListOfLists, Seperator)), i.e,
>> 
>> Y = ["a", "b", "c"]
>> "a, b, c" = lists:intercalate(Y, ", "),
>> 
>> The implementations are straightforward and easy to write tests for, even
>> property based tests if needed.
>> 
>> The rationale for this proposal is that I find myself implementing this
>> function again and again in every project I write, and it is highly
>> generic. It belongs in a typical list module. OCaml libraries add it.
>> Haskell's Data.List has it. I believe Erlang, being a practical language,
>> should have it as well.
>> 
>> Thoughts?
> 
> +1
> 
> Though I prefer the name "interleave" to "intersperse", since its meaning is more-precise and closer to the intended behavior here.
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