在榆樹字典

Question

我定義我的模型是Model = Dict Int String然而，在編譯時使用詮釋或數字，我得到number代替Int所以它是錯誤的：

The 2nd argument to function `get` is causing a mismatch. 

71|    Dict.get 3 model 
          ^^^^^ 
Function `get` is expecting the 2nd argument to be: 

    Dict number v 

But it is: 

    Model 

，不幸的是榆樹REPL不返回Dict number同樣的事情而不是Dict Int。

> Dict.fromList [ (1, {a= 1})] 
Dict.fromList [(1,{ a = 1 })] : Dict.Dict number { a : number1 } 

某些語言如Haskell中暴露Int作爲以及Integer以及number我怎麼能強迫它是整數？

Answer 1

你能提供相關的代碼嗎？

下面的編譯和我工作得很好：

import Dict exposing (Dict, fromList, get) 

type alias Model = Dict Int String 

model : Model 
model = fromList [(1, "apple"), (2, "banana"), (42, "giraffe")] 

test : Maybe String 
test = get 2 model