Question 135963 in Visual Studio Code Question posted in
View the official documentation.

Visual Studio Code – In F# is it OK to make a shorthand function to print using %A

I’m just starting to use F# for the first time, using VSCode and interactive notebooks. I am super annoyed at having to constantly write out

printfn "%A" something

because it kills me inside.

Is it wrong to at the start of every file simply write:

let print(something) = printfn "%A" something

// then use with

print(4 + 3) // int
print(3.7 + 1.1) //float
print("this is so much better") // text

Why the heck isn’t this built in?!

Tags:

2

Answers


  1. 0

    It turned out to be non trivial to make this built-in. Not because it’s a technical challenge, but because there’s not a single answer to “how to print X”, when the type is generic. Should it use internationalisation or not? Should it work like ToString? Should it behave like %A, which is slow and has changed between F# versions?

    An implementation was made, and then halted, precisely because we didn’t have a definitive answer to these questions. I have an opinion and a preference, but my preference may not be yours. Which is why this isn’t as trivial as we’d like it to be.

    That said, it is very common to have a little helper function like you wrote. Perhaps you’d make another one with %O (which takes ToString() behaviour). I often also make one specific for logging that behaves like printfn, but logs it somewhere.

    The presence of interpolated strings has made the requirement for such helpers a little less demanding. But sure enough, functions that just dump the contents of a type are still very common.

    Login or Signup to reply.
  2. 0

    Yes, of course, it’s ok to do this. Perhaps the easiest is to

    open type System.Console

    And then use

    WriteLine (4 + 3) // int
WriteLine (3.7 + 1.1) //float
WriteLine "this is so much better" // text
    Login or Signup to reply.
Please signup or login to give your own answer.

Back To Top
Search