bob elixir solution

elixir/bob/lib/bob.ex

@@ -0,0 +1,31 @@
+defmodule Bob do
+  def hey(input) do
+    input = String.trim(input)
+
+    uppercase =
+      Enum.all?(
+        Enum.filter(String.graphemes(input), &String.match?(&1, ~r/^\p{L}$/u)),
+        &String.match?(&1, ~r/^\p{Lu}$/u)
+      )
+
+    has_letters = Enum.any?(String.graphemes(input), &String.match?(&1, ~r/^\p{L}$/u))
+    question = String.ends_with?(input, "?")
+
+    cond do
+      String.length(input) == 0 ->
+        "Fine. Be that way!"
+
+      has_letters && uppercase && question ->
+        "Calm down, I know what I'm doing!"
+
+      question ->
+        "Sure."
+
+      has_letters && uppercase ->
+        "Whoa, chill out!"
+
+      true ->
+        "Whatever."
+    end
+  end
+end