I would be all for changing the way Kernel is imported to allow a name that exists in Kernel to be redefined (potentially generating a warning), because regardless of what name we choose, if this behaviour is not altered then adding any function to Kernel will be a breaking change.
On the other hand: I do not think this is the first time that a new function is added to kernel after 1.0 (or is it)? What approach was taken in those earlier cases? ~Marten/Qqwy On Wednesday, July 3, 2019 at 2:16:22 PM UTC+2, Alexis Brodeur wrote: > > While this is a great idea, and I am overall in favor of an > `Kernel.identity/1`, let me play devil's advocate for a bit... > > According to lib/elixir/src/elixir_locals.erl > <https://github.com/elixir-lang/elixir/blob/master/lib/elixir/src/elixir_locals.erl#L92>, > > all `def`s in a module are validated to not clash against an already > imported function from other modules. By introducing `Kernel.identity/1`, > modules in the wild already using a `identity/1` function would cease to > compile, therefore making this change a breaking one, according to my > current understanding of the compiler. > > A simple `test.exs` module > ```ex > defmodule Test do > def test do > inspect("term") > end > > def inspect(term, opts \\ []) do > IO.puts("my inspect/2") > end > end > > Test.test > ``` > > against the current `master` of elixir yields: > ``` > == Compilation error in file /Users/brodeuralexis/test.exs == > ** (CompileError) /Users/brodeuralexis/test.exs:6: imported > Kernel.inspect/1 conflicts with local function > (elixir) src/elixir_locals.erl:94: > :elixir_locals."-ensure_no_import_conflict/3-lc$^0/1-0-"/2 > (elixir) src/elixir_locals.erl:95: anonymous fn/3 in > :elixir_locals.ensure_no_import_conflict/3 > /Users/brodeuralexis/test.exs:1: (file) > ``` > > On Tuesday, July 2, 2019 at 5:23:47 AM UTC-4, Alexey Nikitin wrote: >> >> Like Haskell's `id` or Clojure's `identity` or Ruby's `itself` >> >> It can be very useful sometimes. Instead of writing ugly `&(&1)` it would >> much more attractive to write `&identity/1` or `&id\1` >> Moreover this function is already used as a default argument for some >> higher-order function. For example `Enum.group_by(enumerable, key_fun, >> value_fun \\ fn x -> x end)` >> >> Here are some examples >> >> ``` >> #=> [1, 2, 3, true, 1234] >> >> 'abcdaabccc' |> Enum.sort |> Enum.chunk_by(&identity/1) >> #=> ['aaa', 'bb', 'cccc', 'd'] >> >> [1, 1, 2, 3, 3, 1, 1, 5, 5] |> Enum.chunk_by(&identity/1) |> >> Enum.map(&hd/1) >> #=> [1, 2, 3, 1, 5] >> >> Enum.group_by('abracadabra', &identity/1) >> #=> %{97 => 'aaaaa', 98 => 'bb', 99 => 'c', 100 => 'd', 114 => 'rr'} >> >> Enum.map([1, 2, 3, 4], &identity/1) >> #=> [1, 2, 3, 4] >> [1,2,3,nil, true, false, 1234] |> Enum.filter(&identity/1) >> ``` >> > -- 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+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/f87de323-20b7-4616-843c-10863a4c079d%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
