Haskell 鏀寔閫掑綊鏁版嵁缁撴瀯锛屽叾涓渶甯歌鐨勬柟寮忔槸浣跨敤浠ｆ暟鏁版嵁绫诲瀷銆備唬鏁版暟鎹被鍨嬪厑璁稿畾涔夎嚜宸辩殑鏁版嵁绫诲瀷锛屽叾涓彲浠ュ寘鍚瀯閫犲櫒锛岃繖浜涙瀯閫犲櫒鍙互鍖呭惈閫掑綊寮曠敤鑷韩鐨勭被鍨嬨€備緥濡傦紝涓嬮潰鏄竴涓畾涔変簩鍙夋爲鐨勪唬鏁版暟鎹被鍨嬬殑渚嬪瓙锛?/p>

data BinaryTree a = Leaf
                 | Node a (BinaryTree a) (BinaryTree a)

鍦ㄨ繖涓緥瀛愪腑锛?code>BinaryTree 鏄竴涓唬鏁版暟鎹被鍨嬶紝鍏朵腑鍖呭惈涓や釜鏋勯€犲櫒锛?code>Leaf 琛ㄧず绌哄彾瀛愯妭鐐癸紝Node 琛ㄧず涓€涓寘鍚€煎拰涓や釜瀛愭爲鐨勮妭鐐广€傝繖閲岀殑 BinaryTree a 鏄€掑綊瀹氫箟鐨勶紝鍥犱负 Node 鏋勯€犲櫒鐨勫弬鏁版槸 BinaryTree a 绫诲瀷銆?/p>

浣跨敤閫掑綊鏁版嵁缁撴瀯鏃讹紝浣犲彲浠ヤ娇鐢ㄩ€掑綊鍑芥暟鏉ュ鐞嗚繖浜涙暟鎹粨鏋勩€備緥濡傦紝涓嬮潰鏄竴涓绠椾簩鍙夋爲鍙跺瓙鑺傜偣鏁扮殑鍑芥暟锛?/p>

countLeaves :: BinaryTree a -> Int
countLeaves Leaf = 1
countLeaves (Node _ left right) = countLeaves left + countLeaves right

鍦ㄨ繖涓緥瀛愪腑锛?code>countLeaves 鍑芥暟閫掑綊鍦伴亶鍘嗕簩鍙夋爲锛屽鏋滈亣鍒板彾瀛愯妭鐐瑰垯杩斿洖 1锛屽惁鍒欓€掑綊鍦拌绠楀乏鍙冲瓙鏍戠殑鍙跺瓙鑺傜偣鏁板苟鐩稿姞銆?/p>

閫氳繃浠ｆ暟鏁版嵁绫诲瀷鍜岄€掑綊鍑芥暟锛孒askell 鑳藉寰堟柟渚垮湴鏀寔閫掑綊鏁版嵁缁撴瀯鐨勫畾涔夊拰鎿嶄綔銆?/p>