Haskell 哈夫曼译码调试

当我调试哈夫曼解码函数时

decode :: (Tree a, [Bit]) -> [a]
decode (tree, list) = case list of
 [] -> case tree of
   Leaf pos a -> replicate_Pos pos a
 _  -> (num_only (follow_bit_path_to_one_value tree list)): huffman_decode (tree, (list_only (follow_bit_path_to_one_value tree list))
   where 
    num_only :: (a, [Bit]) -> a
    num_only (a, _) -> a
    list_only:: (a, [Bit]) -> [Bit]
    list_only (_, list) -> list

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它在输入“where”时出现了一个解析错误？我哪里做错了？

这段代码的真正问题是括号不匹配，而不是大小写表达式中的缩进。此外，还有箭头，而不是

=

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下面的代码解析得很好

decode :: (Tree a, [Bit]) -> [a]
decode (tree, list) = case list of
 [] -> case tree of
   Leaf pos a -> replicate_Pos pos a
 _  -> (num_only (follow_bit_path_to_one_value tree list)): huffman_decode (tree, (list_only (follow_bit_path_to_one_value tree list)))
   where 
    num_only :: (a, [Bit]) -> a
    num_only (a, _) = a
    list_only:: (a, [Bit]) -> [Bit]
    list_only (_, list) = list