2 Matching Annotations
  1. Apr 2024
    1. let map oneTrackFunction twoTrackInput = match twoTrackInput with | Success s -> Success (oneTrackFunction s) | Failure f -> Failure f And here it is in use with canonicalizeEmail: let usecase = validate1 >=> validate2 >=> validate3 >> map canonicalizeEmail // normal composition Note that normal composition is now used because map canonicalizeEmail is a fully two-track function and can be connected to the output of the validate3 switch directly. In other words, for one-track functions, >=> switch is exactly the same as >> map. Your choice.

      QUESTION

      map can be defined using bind and switch,

      let map f = bind (switch f)

      but how to do this with >=>?...

      ANSWER

      Found a solution, but this is quite stupid:

      let map' f result = match result with // The value of `o` is irrelevant, it is only needed // because `>=>` returns a function, but we need // a value and both operands of the input `f` are // provided by the closures | Ok o -> ((fun _ -> result) >=> (switch f)) o | Error e -> Error e

      NOTE<br /> Call them as: map ((+) 2) ((Ok 27) : Result<int,string>);; map' ((+) 2) ((Ok 27) : Result<int,string>);;

  2. Feb 2021