Refactor part 1

Author: timocp

src/day3.gleam

@@ -5,18 +5,15 @@ import gleam/regexp
 import gleam/result
 
 pub fn part1(input: String) -> Int {
-  let assert Ok(re) = regexp.from_string("mul\\((\\d+),(\\d+)\\)")
-  regexp.scan(re, input)
-  |> list.map(fn(match) {
-    match.submatches
-    |> list.map(fn(submatch) { option.unwrap(submatch, "") })
-    |> list.filter_map(int.parse)
-  })
-  |> list.map(fn(mul) {
-    mul |> list.reduce(fn(acc, m) { acc * m }) |> result.unwrap(0)
+  input
+  |> parse_input
+  |> list.map(fn(token) {
+    case token {
+      Mul(a, b) -> a * b
+      _ -> 0
+    }
   })
-  |> list.reduce(fn(acc, v) { acc + v })
-  |> result.unwrap(0)
+  |> list.fold(0, fn(acc, v) { acc + v })
 }
 
 pub fn part2(input: String) -> Int {