refactor: extract functions

2024/day07.scala

@@ -3,14 +3,9 @@ package `2024`.day07
 import prelude.*
 import scala.annotation.tailrec
 
-def digits(x: Long) = math.log10(x.toDouble).toInt + 1
-
 extension (a: Long)
   inline def ||(b: Long) = (a * math.pow(10, digits(b)) + b).toLong
 
-extension [C <: Iterable, A](xs: C[A])
-  def orEmpty[B](f: C[A] => B)(els: => B) = if (xs.isEmpty) els else f(xs)
-
 type Op = Long => Long => List[Long]
 
 def getCombo(xs: List[Long], next: Op) =

prelude/iterable.scala

@@ -13,4 +13,12 @@ extension [A](xs: IterableOnce[A])
     * items.map(_.length).sum  // 6
     * }}}
     */
-  inline def sumBy[B >: Int](f: A => B)(using Numeric[B]): B = xs.iterator.map(f).sum
+  inline def sumBy[B >: Int](f: A => B)(using Numeric[B]): B =
+    xs.iterator.map(f).sum
+
+extension [C <: Iterable, A](xs: C[A])
+  /** Maps the iterable to a new iterable using the given function `f` if the
+    * iterable is not empty. Otherwise, returns the given value `default`.
+    */
+  def orEmpty[B](f: C[A] => B)(default: => B) =
+    if (xs.isEmpty) default else f(xs)

prelude/math.scala

@@ -1,5 +1,8 @@
 package prelude
 
+def digits(x: Int) = math.log10(x.toDouble).toInt + 1
+def digits(x: Long) = math.log10(x.toDouble).toInt + 1
+
 extension (n: Int)
   inline infix def divmod(d: Int) = (n / d, n % d)
   inline infix def moddiv(d: Int) = (n % d, n / d)