Add comments to const

cell.go

@@ -34,16 +34,34 @@ var (
 	ErrUnflaggingNonFlaggedCell = errors.New("non-flagged cell can not be unflagged")
 )
 
+// CellState depicts a state of a cell.
+type CellState int
+
 const (
 	_ CellState = iota
+
+	// Closed represents a state of a cell where no operation is currently applied.
+	//
+	// A cell with this state may or may not have underlying land mine.
 	Closed
+
+	// Opened represents a state of a cell where the cell is dug and is secure.
+	//
+	// This is final and no more operation can be applied to its belonging cell.
 	Opened
+
+	// Flagged represents a state of a cell that is marked by a user to indicate possible underlying mine.
+	//
+	// To open this cell, user must unflag the cell first.
 	Flagged
+
+	// Exploded represents a state of a cell where user tried to open, but had an underlying mine.
+	//
+	// This is final and no more operation can be applied to its belonging cell.
 	Exploded
 )
 
-type CellState int
-
+// String returns stringified representation of CellState.
 func (s CellState) String() string {
 	switch s {
 	case Closed:

game.go

@@ -14,24 +14,43 @@ var (
 	ErrOperatingFinishedGame = errors.New("can not operate on finished game")
 )
 
+// GameState depicts state of the game.
+//
+// When Cleared or Lost is returned from Game.Operate, the game is finished and no further operation is available.
 type GameState int
 
 const (
 	_ GameState = iota
+
+	// InProgress represents a state of a game where the game is not finished yet and user operation is available.
 	InProgress
+
+	// Cleared represents a state of a game where all safe cells are opened.
+	//
+	// This state is final so any further Game.Operate call results in returning GameState of Cleared and ErrOperatingFinishedGame.
 	Cleared
+
+	// Lost represents a state of a game where non-safe cell was dug and underlying mine has exploded.
 	Lost
 )
 
+// OpType represents a type of operation a user is applying.
 type OpType int
 
 const (
 	_ OpType = iota
+
+	// Open represents a kind of operation to open a closed field cell.
 	Open
+
+	// Flag represents a kind of operation to flag a closed suspicious field cell with a possible underlying mine.
 	Flag
+
+	// Unflag represents a kind of operation to unflag a flagged field cell.
 	Unflag
 )
 
+// String returns stringified representation of GameState.
 func (s GameState) String() string {
 	switch s {
 	case InProgress:
@@ -49,6 +68,7 @@ func (s GameState) String() string {
 	}
 }
 
+// MarshalJSON returns GameState value that can be part of JSON structure.
 func (s GameState) MarshalJSON() ([]byte, error) {
 	return []byte(fmt.Sprintf(`"%s"`, s.String())), nil
 }