diff --git a/Sources/geometrize/Core.swift b/Sources/geometrize/Core.swift
index 3cba73e..dea5abd 100644
--- a/Sources/geometrize/Core.swift
+++ b/Sources/geometrize/Core.swift
@@ -1,54 +1,5 @@
 import Foundation
 
-// The core functions for Geometrize.
-
-/// Type alias for a function that calculates a measure of the improvement adding
-/// the scanlines of a shape provides - lower energy is better.
-/// - Parameters:
-///   - lines The scanlines of the shape.
-///   - alpha The alpha of the scanlines.
-///   - target The target bitmap.
-///   - current The current bitmap.
-///   - buffer The buffer bitmap.
-///   - score The score.
-/// - Returns: The energy measure.
-public typealias EnergyFunction = (
-    _ lines: [Scanline],
-    _ alpha: UInt8,
-    _ target: Bitmap,
-    _ curent: Bitmap,
-    _ buffer: inout Bitmap,
-    _ score: Double
-) -> Double
-
-/// The default/built-in energy function that calculates a measure of the improvement adding
-/// the scanlines of a shape provides - lower energy is better.
-/// - Parameters:
-///   - lines: The scanlines of the shape.
-///   - alpha:  The alpha of the scanlines.
-///   - target: The target bitmap.
-///   - current: The current bitmap.
-///   - buffer: The buffer bitmap.
-///   - score: The score.
-/// - Returns: The energy measure.
-public func defaultEnergyFunction( // swiftlint:disable:this function_parameter_count
-    _ lines: [Scanline],
-    _ alpha: UInt8,
-    _ target: Bitmap,
-    _ current: Bitmap,
-    _ buffer: inout Bitmap,
-    _ score: Double
-) -> Double {
-    // Calculate best color for areas covered by the scanlines
-    let color: Rgba = computeColor(target: target, current: current, lines: lines, alpha: UInt8(alpha))
-    // Copy area covered by scanlines to buffer bitmap
-    buffer.copy(lines: lines, source: current)
-    // Blend scanlines into the buffer using the color calculated earlier
-    buffer.draw(lines: lines, color: color)
-    // Get error measure between areas of current and modified buffers covered by scanlines
-    return current.differencePartial(with: buffer, target: target, score: score, mask: lines)
-}
-
 /// Calculates the color of the scanlines.
 /// - Parameters:
 ///   - target: The target image.
diff --git a/Sources/geometrize/EnergyFunction.swift b/Sources/geometrize/EnergyFunction.swift
new file mode 100644
index 0000000..c1805a8
--- /dev/null
+++ b/Sources/geometrize/EnergyFunction.swift
@@ -0,0 +1,48 @@
+import Foundation
+
+/// Type alias for a function that calculates a measure of the improvement adding
+/// the scanlines of a shape provides - lower energy is better.
+/// - Parameters:
+///   - lines The scanlines of the shape.
+///   - alpha The alpha of the scanlines.
+///   - target The target bitmap.
+///   - current The current bitmap.
+///   - buffer The buffer bitmap.
+///   - score The score.
+/// - Returns: The energy measure.
+public typealias EnergyFunction = (
+    _ lines: [Scanline],
+    _ alpha: UInt8,
+    _ target: Bitmap,
+    _ curent: Bitmap,
+    _ buffer: inout Bitmap,
+    _ score: Double
+) -> Double
+
+/// The default/built-in energy function that calculates a measure of the improvement adding
+/// the scanlines of a shape provides - lower energy is better.
+/// - Parameters:
+///   - lines: The scanlines of the shape.
+///   - alpha:  The alpha of the scanlines.
+///   - target: The target bitmap.
+///   - current: The current bitmap.
+///   - buffer: The buffer bitmap.
+///   - score: The score.
+/// - Returns: The energy measure.
+public func defaultEnergyFunction( // swiftlint:disable:this function_parameter_count
+    _ lines: [Scanline],
+    _ alpha: UInt8,
+    _ target: Bitmap,
+    _ current: Bitmap,
+    _ buffer: inout Bitmap,
+    _ score: Double
+) -> Double {
+    // Calculate best color for areas covered by the scanlines
+    let color: Rgba = computeColor(target: target, current: current, lines: lines, alpha: UInt8(alpha))
+    // Copy area covered by scanlines to buffer bitmap
+    buffer.copy(lines: lines, source: current)
+    // Blend scanlines into the buffer using the color calculated earlier
+    buffer.draw(lines: lines, color: color)
+    // Get error measure between areas of current and modified buffers covered by scanlines
+    return current.differencePartial(with: buffer, target: target, score: score, mask: lines)
+}