Make ScaleType CustomStringConvertible

Source/ChordProgression.swift

@@ -9,11 +9,17 @@
 import Foundation
 
 /// A struct for storing custom progressions.
-public struct CustomChordProgression: Codable {
+public struct CustomChordProgression: Codable, CustomStringConvertible {
   /// Name of the progression.
   public var name: String
   /// Chord progression with `ChordProgresion.custom` type.
   public var progression: ChordProgression
+
+  // MARK: CustomStringConvertible
+
+  public var description: String {
+    return name
+  }
 }
 
 /// A node of chord progression in intervals.

Source/Scale.swift

@@ -13,7 +13,7 @@ import Foundation
 // MARK: - ScaleType
 
 /// Represents scale by the intervals between note sequences.
-public struct ScaleType: Equatable {
+public struct ScaleType: Equatable, CustomStringConvertible {
   /// Major scale.
   public static let major = ScaleType(intervals: ScaleType.ionian.intervals, description: "Major")
   /// Minor scale.

Source/Tempo.swift

@@ -11,10 +11,9 @@
 import Foundation
 
 /// Defines the tempo of the music with beats per second and time signature.
-public struct Tempo: Codable {
+public struct Tempo: Codable, CustomStringConvertible {
   /// Time signature of music.
   public var timeSignature: TimeSignature
-
   /// Beats per minutes.
   public var bpm: Double
 
@@ -49,4 +48,10 @@ public struct Tempo: Codable {
   public func hertz(of noteValue: NoteValue) -> Double {
     return 1 / duration(of: noteValue)
   }
+
+  // MARK: CustomStringConvertible
+
+  public var description: String {
+    return "\(bpm)"
+  }
 }

Source/TimeSignature.swift

@@ -11,10 +11,9 @@
 import Foundation
 
 /// Defines how many beats in a measure with which note value.
-public struct TimeSignature: Codable {
+public struct TimeSignature: Codable, CustomStringConvertible {
   /// Beats per measure.
   public var beats: Int
-
   /// Note value per beat.
   public var noteValue: NoteValueType
 
@@ -41,4 +40,10 @@ public struct TimeSignature: Codable {
     self.beats = beats
     self.noteValue = noteValue
   }
+
+  // MARK: CustomStringConvertible
+
+  public var description: String {
+    return "\(beats)/\(Int(noteValue.rawValue))"
+  }
 }