Haskell語言Maybe模塊中函數maybeToList的用法及代碼示例。
用法類型:
Maybe a -> [a]
如果參數是Just,則返回以Just值為元素的列表,否則返回空列表
示例1:
輸入:
maybeToList (lookup 3 [(1,'A'),(2,'B'),(3,'C')])
輸出:
"C"
示例2:
輸入:
maybeToList (lookup 3 [(1,11),(2,22),(3,33)])
輸出:
[33]
示例3:
輸入:
maybeToList (lookup 32 [(1,'A'),(2,'B'),(3,'C')])
輸出:
""
示例4:
輸入:
maybeToList (lookup 32 [(1,11),(2,22),(3,33)])
輸出:
[]
相關用法
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