Add retrocompatibility with as far as Elixir 1.7 and OTP 21.3

Beyond that, the cost becomes too high (no __STACKTRACE__, no persistent
term, etc.)

Besides, with Elixir 1.7 having been released in 2018, I think this is a
very nice addition already.

.github/workflows/ci.yml

@@ -13,7 +13,8 @@ on:
   workflow_dispatch: # enables "click to run" button
 
 env:
-  HIGHEST_ELIXIR_VERSION_IN_MATRIX: '1.15'
+  ELIXIR_VERSION_ON_WHICH_TO_CHECK_STYLE: '1.15' # Should be highest in matrix
+  ELIXIR_VERSIONS_ON_WHICH_TO_RUN_DIALYZER: "['1.12', '1.13', '1.14', '1.15']"
 
 jobs:
   ci:
@@ -23,6 +24,11 @@ jobs:
     strategy:
       matrix:
         elixir_vsn: [
+          '1.7',
+          '1.8',
+          '1.9',
+          '1.10',
+          '1.11',
           '1.12',
           '1.13',
           '1.14',
@@ -77,17 +83,18 @@ jobs:
         run: mix do deps.get, deps.clean --unused
 
       - name: Assert code is formatted
-        if: ${{matrix.elixir_vsn == env.HIGHEST_ELIXIR_VERSION_IN_MATRIX}}
+        if: ${{matrix.elixir_vsn == env.ELIXIR_VERSION_ON_WHICH_TO_CHECK_STYLE}}
         run: mix format --check-formatted
 
       - name: Run Credo
-        if: ${{matrix.elixir_vsn == env.HIGHEST_ELIXIR_VERSION_IN_MATRIX}}
+        if: ${{matrix.elixir_vsn == env.ELIXIR_VERSION_ON_WHICH_TO_CHECK_STYLE}}
         run: mix credo --strict
 
       - name: Run tests
         run: mix test --cover
 
       - name: Run Dialyzer
+        if: ${{contains(fromJson(env.ELIXIR_VERSIONS_ON_WHICH_TO_RUN_DIALYZER), matrix.elixir_vsn)}}
         run: MIX_ENV=test mix dialyzer
 
       - name: Save build artifacts to cache

.github/workflows/elixir_version_to_otp_version.json

@@ -1,4 +1,9 @@
 {
+    "1.7": "21.3",
+    "1.8": "22.3",
+    "1.9": "22.3",
+    "1.10": "23.3",
+    "1.11": "24.3",
     "1.12": "24.3",
     "1.13": "25.3",
     "1.14": "26.1",

README.md

@@ -2,7 +2,8 @@
 
 [![](https://img.shields.io/hexpm/v/sqids.svg?style=flat)](https://hex.pm/packages/sqids)
 [![](https://github.com/sqids/sqids-elixir/actions/workflows/ci.yml/badge.svg)](https://github.com/sqids/sqids-elixir/actions/workflows/ci.yml)
-[![Elixir Versions](https://img.shields.io/badge/Compatible%20with%20Elixir-1.12%20to%201.15-blue)](https://elixir-lang.org/)
+[![Elixir Versions](https://img.shields.io/badge/Compatible%20with%20Elixir-1.7%20to%201.15-blue)](https://elixir-lang.org/)
+[![Erlang Versions](https://img.shields.io/badge/Supported%20Erlang%2FOTP-21.3%20to%2026-blue)](https://www.erlang.org)
 
 
 [Sqids](https://sqids.org/elixir) (*pronounced "squids"*) for Elixir is a

lib/sqids/alphabet.ex

@@ -1,6 +1,6 @@
 defmodule Sqids.Alphabet do
   @moduledoc false
-  # import ExUnit.Assertions
+  import ExUnit.Assertions
 
   @min_alphabet_length 3
 
@@ -106,13 +106,12 @@ defmodule Sqids.Alphabet do
   @spec index_of!(t(), byte) :: index
   def index_of!(%{} = alphabet, char) do
     # It would be nice to optimize this.
-    alphabet
-    |> Enum.find_value(fn {index, byte} ->
-      byte == char and index
-    end)
-    |> then(fn index when index != nil ->
-      index
-    end)
+
+    index =
+      Enum.find_value(alphabet, fn {index, byte} -> byte == char and index end)
+
+    assert index !== nil
+    index
   end
 
   ## Internal

lib/sqids/blocklist.ex

@@ -72,19 +72,19 @@ defmodule Sqids.Blocklist do
     alphabet_graphemes_downcased = alphabet_str |> String.downcase() |> String.graphemes() |> MapSet.new()
     sort_fun = fn word -> {String.length(word), word} end
 
-    words
-    |> Enum.uniq()
-    |> Enum.reduce(
-      _acc0 = %__MODULE__{min_word_length: min_word_length},
-      &maybe_add_blocklist_entry(&1, &2, alphabet_graphemes_downcased)
-    )
-    |> then(fn blocklist ->
-      %{
-        blocklist
-        | prefixes_and_suffixes: Enum.sort_by(blocklist.prefixes_and_suffixes, sort_fun),
-          matches_anywhere: Enum.sort_by(blocklist.matches_anywhere, sort_fun)
-      }
-    end)
+    blocklist =
+      words
+      |> Enum.uniq()
+      |> Enum.reduce(
+        _acc0 = %__MODULE__{min_word_length: min_word_length},
+        &maybe_add_blocklist_entry(&1, &2, alphabet_graphemes_downcased)
+      )
+
+    %{
+      blocklist
+      | prefixes_and_suffixes: Enum.sort_by(blocklist.prefixes_and_suffixes, sort_fun),
+        matches_anywhere: Enum.sort_by(blocklist.matches_anywhere, sort_fun)
+    }
   end
 
   @spec maybe_add_blocklist_entry(String.t(), t(), MapSet.t(String.grapheme())) :: t()

mix.exs

@@ -7,7 +7,7 @@ defmodule Sqids.MixProject do
     [
       app: :sqids,
       version: "0.1.0",
-      elixir: "~> 1.12",
+      elixir: "~> 1.7",
       start_permanent: Mix.env() == :prod,
       deps: deps(),
       elixirc_paths: elixirc_paths(Mix.env()),
@@ -27,23 +27,40 @@ defmodule Sqids.MixProject do
           threshold: 94
         ]
       ],
+      dialyzer: [plt_add_apps: [:ex_unit]],
       package: package()
     ]
   end
 
   # Run "mix help deps" to learn about dependencies.
   defp deps do
     List.flatten([
-      {:credo, "~> 1.7", only: [:dev, :test], runtime: false},
-      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false},
       {:ex_doc, "~> 0.30", only: :dev, runtime: false},
       {:recon, "~> 2.5", only: [:dev, :test], runtime: false},
       {:sqids_blocklist,
        github: "sqids/sqids-blocklist", branch: "main", only: :dev, runtime: false, app: false, compile: false},
+      maybe_credo_dep(),
+      maybe_dialyxir_dep(),
       maybe_styler_dep()
     ])
   end
 
+  defp maybe_credo_dep do
+    if Version.match?(System.version(), "~> 1.12") do
+      {:credo, "~> 1.7", only: [:dev, :test], runtime: false}
+    else
+      []
+    end
+  end
+
+  defp maybe_dialyxir_dep do
+    if Version.match?(System.version(), "~> 1.12") do
+      {:dialyxir, "~> 1.4", only: [:dev, :test], runtime: false}
+    else
+      []
+    end
+  end
+
   defp maybe_styler_dep do
     if Version.match?(System.version(), "~> 1.14") do
       {:styler, "~> 0.8", only: [:dev, :test], runtime: false}

scripts/update_blocklist.exs

@@ -35,24 +35,24 @@ defmodule Sqids.BlocklistUpdater do
   defp convert_from_canonical_list do
     log_step("Converting canonical blocklist...")
 
-    @path_of_canonical_json
-    |> File.read!()
-    |> Jason.decode!()
-    |> :lists.usort()
-    |> Enum.reduce(
-      _acc0 = "",
-      fn word, acc ->
-        refute match?(
-                 {true, _},
-                 {String.contains?(word, ["\n", "\r"]), word}
-               )
-
-        [acc, word, "\n"]
-      end
-    )
-    |> then(fn blocklist ->
-      File.write!(@path_of_txt_copy, blocklist)
-    end)
+    blocklist =
+      @path_of_canonical_json
+      |> File.read!()
+      |> Jason.decode!()
+      |> :lists.usort()
+      |> Enum.reduce(
+        _acc0 = "",
+        fn word, acc ->
+          refute match?(
+                   {true, _},
+                   {String.contains?(word, ["\n", "\r"]), word}
+                 )
+
+          [acc, word, "\n"]
+        end
+      )
+
+    File.write!(@path_of_txt_copy, blocklist)
   end
 
   defp maybe_update_changelog do

test/sqids_test.exs

@@ -1,10 +1,14 @@
 defmodule SqidsTest do
   # doctest Sqids
 
+  require Bitwise
+
   ## Shared between test cases
 
   defmodule Shared do
+    @moduledoc false
     defmodule UsingModule do
+      @moduledoc false
       use Sqids
     end
 
@@ -53,6 +57,7 @@ defmodule SqidsTest do
 
     def assert_encode_and_back(sqids, numbers) do
       import ExUnit.Assertions
+
       assert decode!(sqids, encode!(sqids, numbers)) === numbers
     end