1 files changed, 32 insertions, 0 deletions
diff --git a/aoc-2020-gleam/src/util/runner.gleam b/aoc-2020-gleam/src/util/runner.gleam
new file mode 100644
index 0000000..0ff0a41
--- /dev/null
+++ b/aoc-2020-gleam/src/util/runner.gleam
@@ -0,0 +1,32 @@
+import gleam/list
+import gleam/int
+import gleam/io
+import gleam/result
+import gleam/erlang.{start_arguments}
+
+fn get_day(handler: fn(Int) -> Nil) -> Result(Nil, String) {
+  let args = start_arguments()
+
+  use first <- result.then(
+    args
+    |> list.first()
+    |> result.replace_error("Pass the day as first argument!"),
+  )
+
+  use day <- result.then(
+    first
+    |> int.parse()
+    |> result.replace_error("The day argument must be a number!"),
+  )
+
+  handler(day)
+
+  Ok(Nil)
+}
+
+pub fn with_day(handler: fn(Int) -> Nil) -> Nil {
+  handler
+  |> get_day()
+  |> result.map_error(io.println)
+  |> result.unwrap(Nil)
+}