考虑
type alias Rec = { a: Int, b: Int, c:Int } updateRec r aVal = { r|a = aVal } updateRec2 r aVal bVal = { r|a = aVal, b= bVal } updateRec3 r aVal bVal cVal = ...如何将updateRec和updateRec2 ...概括为一个函数？
Consider
type alias Rec = { a: Int, b: Int, c:Int } updateRec r aVal = { r|a = aVal } updateRec2 r aVal bVal = { r|a = aVal, b= bVal } updateRec3 r aVal bVal cVal = ...How to generalize updateRec and updateRec2... into one function?
最满意答案
这是做同样事情的更好方法：
updateA : Int -> Rec -> Rec updateA x rec = { rec | a = x } -- Similarly for b, c现在您可以执行以下操作，假设您已经有值rec : Rec想要更新：
myUpdatedRec : Rec myUpdatedRec = rec |> updateA 7 |> updateB 19您现在可以通过串联更新任意数量的字段|> updateX ...
Here's a better way of doing the same thing:
updateA : Int -> Rec -> Rec updateA x rec = { rec | a = x } -- Similarly for b, cNow you can do the following, supposing you already have a value rec : Rec you want to update:
myUpdatedRec : Rec myUpdatedRec = rec |> updateA 7 |> updateB 19You can now update an arbitrary number of fields by stringing together |> updateX ....
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