Elm语言创建列表
示例
> listOfNumbers = [1,4,99] [1,4,99] : List number > > listOfStrings = ["Hello","World"] ["Hello","World"] : List String > > emptyList = [] -- can be anything, we don't know yet [] : List a >
在底层，List（链接列表）由::函数（称为“cons”）构造，该函数带有两个参数：一个元素（称为头）和一个（可能为空）列表（头在其前面）。
> withoutSyntaxSugar = 1 :: [] [1] : List number > > longerOne = 1 :: 2 :: 3 :: [] [1,2,3] : List number > > nonemptyTail = 1 :: [2] [1,2] : List number >
List只能采用一种类型的值，因此[1,"abc"]不可能实现。如果需要，请使用元组。
> notAllowed = [1,"abc"]
==================================== ERRORS ====================================
-- TYPE MISMATCH --------------------------------------------- repl-temp-000.elm
The 1st and 2nd elements are different types of values.
8| [1,"abc"]
^^^^^
The 1st element has this type:
number
But the 2nd is:
String
Hint: All elements should be the same type of value so that we can iterate
through the list without running into unexpected values.
>
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