布尔“匹配”表达式是否有 shorthand？

Question

这里有 match 表达式 isVertical 的 shorthand 吗？

let bulmaContentParentTile isVertical nodes =
    let cssClasses =
        let cssDefault = [ "tile"; "is-parent" ]
        match isVertical with
        | true -> cssDefault @ [ "is-vertical" ]
        | _ -> cssDefault

    div [ attr.classes cssClasses ] nodes

我假设像 match isVertical with 这样的表达式很常见，以至于有一个 shorthand 就像我们为 function 所用的那样，不是吗？

Answer 1

是的，它只是一个 if-表达式：

    let cssClasses =
        let cssDefault = [ "tile"; "is-parent" ]
        if isVertical then
            cssDefault @ [ "is-vertical" ]
        else cssDefault

引用自 F# docs:

Unlike in other languages, the if...then...else construct is an expression, not a statement. That means that it produces a value, which is the value of the last expression in the branch that executes.

Answer 2

这有点离题，但您可以使用 Sequence Expressions 来构建您的列表，恕我直言，对于此用例，它更具可读性。

let cssClasses = [
    "tile"
    "is-parent"
    if isVertical then
        "is-vertical"
]

布尔“匹配”表达式是否有 shorthand？

Is there a shorthand for Boolean `match` expressions?

f#

pattern-matching