From e16fe540e1e423b6b13ec41b91eb491dda50f066 Mon Sep 17 00:00:00 2001
From: "exercism-solutions-syncer[bot]"
 <211797793+exercism-solutions-syncer[bot]@users.noreply.github.com>
Date: Wed, 1 Apr 2026 19:28:19 +0000
Subject: [PATCH] elixir/strain/1

---
 solutions/elixir/strain/1/lib/strain.ex | 27 +++++++++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 solutions/elixir/strain/1/lib/strain.ex

diff --git a/solutions/elixir/strain/1/lib/strain.ex b/solutions/elixir/strain/1/lib/strain.ex
new file mode 100644
index 0000000..1b7c4a3
--- /dev/null
+++ b/solutions/elixir/strain/1/lib/strain.ex
@@ -0,0 +1,27 @@
+defmodule Strain do
+  @doc """
+  Given a `list` of items and a function `fun`, return the list of items where
+  `fun` returns true.
+
+  Do not use `Enum.filter`.
+  """
+  @spec keep(list :: list(any), fun :: (any -> boolean)) :: list(any)
+  def keep(list, fun) do
+    list
+    |> Enum.reduce([], &if(fun.(&1), do: [&1 | &2], else: &2))
+    |> Enum.reverse()
+  end
+
+  @doc """
+  Given a `list` of items and a function `fun`, return the list of items where
+  `fun` returns false.
+
+  Do not use `Enum.reject`.
+  """
+  @spec discard(list :: list(any), fun :: (any -> boolean)) :: list(any)
+  def discard(list, fun) do
+    list
+    |> Enum.reduce([], &if(fun.(&1), do: &2, else: [&1 | &2]))
+    |> Enum.reverse()
+  end
+end