An interesting question that should be defined that highlights the main difference between MapSet and List: what is the result of `List.includes_sublist?([1, 2, 3], [1, 1, 1])`? If the answer is `true` then I think the function should still be called `List.subset` because that is what its really determining (i.e the implication is that this operation treats the lists as sets). Alternatively, `List.all_contained?(subject, search)` may be clearer, and lends itself to further additions like `List.any_contained?` and `List.none_contained?`.
On Fri, Jul 15, 2022 at 10:16 AM, José Valim < jose.va...@dashbit.co > wrote: > > Thanks for the proposal. > > > The issue with contains? is that it is slightly ambiguous in that it is > unclear if List.contains?(list, [1, 2]) is meant to be positive for [[1, > 2]] or [1, 2]. In Strings there is no such ambiguity. So I would > personally avoid contains? in favor of something clearer. Therefore I > would love to see if other languages have this function and what they call > it. :) > > > Regarding the implementation, I also think one of the several string > lookup techniques could be used here. The recursive approach is better but > it has O(m*n) worst case complexity. The "bad character rule" from Boyer–Moore > ( > https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_string_search_algorithm > ) shouldn't add too much complexity and can provide a meaningful > improvement. > > > On Fri, Jul 15, 2022 at 3:32 PM Julian Somoza < julian. somoza@ gmail. com > ( julian.som...@gmail.com ) > wrote: > > >> Thanks for your replies, >> >> >> yes, it could be an String.contains? analog: >> >> [1,2,"3",4] |> Enum.join |> String.contains?("34") >> [1,:a,"3",4] |> Enum.join |> String.contains?("a3") >> >> About the recursive version, it seems to have best performance: >> >> >> >> >> >> >> >> >> >> El vie, 15 jul 2022 a las 9:38, Aleksei Matiushkin (< aleksei. matiushkin@ >> kantox. com ( aleksei.matiush...@kantox.com ) >) escribió: >> >> >>> I have not benchmarked it, but I believe the recursive approach would be >>> better >>> >>> >>> ``` >>> defmodule MyList do >>> def contains?(list, sublist, strict? \\ false) >>> >>> >>> def contains?(_, [], _), do: true >>> def contains?([], _, _), do: false >>> def contains?([h | t], [hh | _] = sub, strict?) when h != hh, do: not >>> strict? and contains?(t, sub, strict?) >>> def contains?([h | t], [h | tt], strict? ), do: contains?(t, tt, true) or >>> contains?(t, [h | tt], strict? ) >>> end >>> >>> ``` >>> >>> On Fri, Jul 15 , 2022 at 2:07 PM 'eksperimental' via elixir-lang-core < >>> elixir-lang-core@ >>> googlegroups. com ( elixir-lang-core@googlegroups.com ) > wrote: >>> >>> >>>> Hi Julian. >>>> It think it is a good addition. >>>> It is also analog to String.contains?/2 >>>> >>>> On Fri , 15 Jul 2022 04:58:59 -0700 (PDT) >>>> Julian Somoza < https:/ / urldefense. proofpoint. com/ v2/ >>>> url?u=http-3A__julian. >>>> somoza-40gmail. >>>> com&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=T8KKoaIf0UYlrJ_VQC1Qv_48Tje2jygIaQysVTXu2c0&e= >>>> ( >>>> https://urldefense.proofpoint.com/v2/url?u=http-3A__julian.somoza-40gmail.com&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=T8KKoaIf0UYlrJ_VQC1Qv_48Tje2jygIaQysVTXu2c0&e= >>>> ) > wrote: >>>> >>>> > Hi everyone, I was working on a suggestion to add a new function on >>>> > the List module in order to find out if a given sublist is inside >>>> > another list. >>>> > >>>> > We currently have *List.starts_with?/2* but this only match the >>>> > beginning: >>>> > >>>> > iex(1)> List.starts_with?([1, 2, 3], [1, 2]) >>>> > true >>>> > >>>> > Besides, we have *MapSet.subset*, but it ignores the elements order: >>>> > >>>> > iex(1)> MapSet. subset?(MapSet. new([1 ( >>>> http://mapset.subset/?(MapSet.new([1 ) , 2]), MapSet. new ( >>>> http://mapset.new/ ) ([1, 2, 3])) >>>> > true >>>> > >>>> > iex(1)> MapSet. subset?(MapSet. new([2 ( >>>> http://mapset.subset/?(MapSet.new([2 ) , 1]), MapSet. new ( >>>> http://mapset.new/ ) ([1, 2, 3])) >>>> > true >>>> > >>>> > I suggest a new function that works like *List.starts_with?/2* but >>>> > matches the entire list, either at the beginning, middle, or end of >>>> > the list. >>>> > >>>> > iex(1)> List.includes_sublist?([1,2,3,4,5], [2,3]) >>>> > true >>>> > >>>> > iex(1)> List.includes_sublist?([1,2,3,4,5], [1,2]) >>>> > true >>>> > >>>> > iex(1)> List.includes_sublist?([1,2,3,4,5], [3,4,5]) >>>> > true >>>> > >>>> > iex(1)> List2.includes_sublist?([1,2,3,4,5], [1,5]) >>>> > false >>>> > >>>> > I'm sharing with you also the function code: >>>> > >>>> > https:/ / urldefense. proofpoint. com/ v2/ url?u=https-3A__github. >>>> > com_elixir-2Dlang_elixir_pull_11987_commits_2b7eba5f6419f906f565e7d4bfe3d687f3b8b052&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=rqpOP9kyNDkOSBV-I2zlHssI6EVLQQ-iBW1F0k3nqFg&e= >>>> ( >>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_elixir-2Dlang_elixir_pull_11987_commits_2b7eba5f6419f906f565e7d4bfe3d687f3b8b052&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=rqpOP9kyNDkOSBV-I2zlHssI6EVLQQ-iBW1F0k3nqFg&e= >>>> ) >>>> > >>>> > I aim to complement the List.starts_with?/2. This function could be >>>> > the same or even more useful because it finds the ordered sublist >>>> > also in the middle or in the end. >>>> > >>>> > Looking forward for your comments, >>>> > BR, >>>> > Julian Somoza. >>>> > >>>> > >>>> >>>> -- >>>> You received this message because you are subscribed to the Google Groups >>>> "elixir-lang-core" group. >>>> To unsubscribe from this group and stop receiving emails from it, send an >>>> email to elixir-lang-core+unsubscribe@ googlegroups. com ( >>>> elixir-lang-core%2bunsubscr...@googlegroups.com ). >>>> To view this discussion on the web visit https:/ / urldefense. proofpoint. >>>> com/ v2/ url?u=https-3A__groups. google. >>>> com_d_msgid_elixir-2Dlang-2Dcore_62d1588e. >>>> 1c69fb81. 3332c. 1d2dSMTPIN-5FADDED-5FMISSING-2540gmr-2Dmx. google. >>>> com&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=Ckh5t8xdml-Vx3UgfKMNxh3CoSb8IBfBORyYgVxcXsg&e= >>>> ( >>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_msgid_elixir-2Dlang-2Dcore_62d1588e.1c69fb81.3332c.1d2dSMTPIN-5FADDED-5FMISSING-2540gmr-2Dmx.google.com&d=DwICaQ&c=euGZstcaTDllvimEN8b7jXrwqOf-v5A_CdpgnVfiiMM&r=rmhwzhuTk1LyLPLZIrqkat6wS6r2qE3XZKnTTHGaxH8&m=rZfYwgMRyMdd1mpKac91VLHbd0qUJlcEVeNzbceWXvE&s=Ckh5t8xdml-Vx3UgfKMNxh3CoSb8IBfBORyYgVxcXsg&e= >>>> ). >>>> >>> >>> >>> >>> >>> >>> -- >>> *Aleksei Matiushkin* , Software Engineer - R&D >>> >>> Office (+34) 935 679 834 >>> >>> >>> >>> >>> >>> >>> 8 Devonshire Square, London, EC2M 4PL, United Kingdom >>> Torre Mapfre, Planta 22, Marina, 16-18, 08005 Barcelona, Spain >>> *kantox. com ( http://kantox.com/ )* >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> ( http://www.linkedin.com/company/1871617 ) ( >>> http://www.linkedin.com/company/1871617 ) LinkedIn ( >>> https://www.linkedin.com/company/1871617 ) ( https://twitter.com/kantox ) >>> Twitter >>> ( https://twitter.com/kantox ) ( http://www.youtube.com/user/kantoxfx ) >>> YouTube >>> ( https://www.youtube.com/user/kantoxfx ) >>> >>> Kantox Limited is a UK private company with registered company number >>> 07657495 and registered address at 8 Devonshire Square, London EC2M 4PL, >>> United Kingdom. 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