[gleam][roman-numerals] use case statement directly

gleam/roman-numerals/src/roman_numerals.gleam

@@ -1,28 +1,22 @@
-import gleam/list
-
-const value_to_roman = [
-  #(1000, "M"),
-  #(900, "CM"),
-  #(500, "D"),
-  #(400, "CD"),
-  #(100, "C"),
-  #(90, "XC"),
-  #(50, "L"),
-  #(40, "XL"),
-  #(10, "X"),
-  #(9, "IX"),
-  #(5, "V"),
-  #(4, "IV"),
-  #(1, "I"),
-]
-
 pub fn convert(number: Int) -> String {
   convert_iter(number, "")
 }
 
-fn convert_iter(remainder: Int, result: String) -> String {
-  case list.find(value_to_roman, fn(pair) { remainder >= pair.0 }) {
-    Ok(#(value, roman)) -> convert_iter(remainder - value, result <> roman)
-    _ -> result
+fn convert_iter(number: Int, roman: String) -> String {
+  case number {
+    _ if number >= 1000 -> convert_iter(number - 1000, roman <> "M")
+    _ if number >= 900 -> convert_iter(number - 900, roman <> "CM")
+    _ if number >= 500 -> convert_iter(number - 500, roman <> "D")
+    _ if number >= 400 -> convert_iter(number - 400, roman <> "CD")
+    _ if number >= 100 -> convert_iter(number - 100, roman <> "C")
+    _ if number >= 90 -> convert_iter(number - 90, roman <> "XC")
+    _ if number >= 50 -> convert_iter(number - 50, roman <> "L")
+    _ if number >= 40 -> convert_iter(number - 40, roman <> "XL")
+    _ if number >= 10 -> convert_iter(number - 10, roman <> "X")
+    _ if number >= 9 -> convert_iter(number - 9, roman <> "IX")
+    _ if number >= 5 -> convert_iter(number - 5, roman <> "V")
+    _ if number >= 4 -> convert_iter(number - 4, roman <> "IV")
+    _ if number >= 1 -> convert_iter(number - 1, roman <> "I")
+    _ -> roman
   }
 }