如何将 sprintf + 调用包装到单个 function 中，并在 F# 中有两个签名？

Question

I have a function that takes a string and sends it to a terminal:

Print: string -> unit

it is passed to several modules that do this, to simplify the syntax

// printing
let print = settings.Print

and then it's used like that:

print "hello"
print (sprintf "the time is %A" DateTime.UtcNow)

my question is: Can I make two functions, with the same name but two signatures, so I could use it to either print a string, or a sprintf, then print the string. for example:

print "hello"
print "the time is %A" DateTime.UtcNow

Is this possible? the goal is to simplify the syntax as a lot of code is peppered with info being sent to the terminal (which is currently a Telegram channel)

Answer 1

You can use kprintf for this:

let myPrint s = printfn "My print: %s !" s

let print x = Printf.kprintf myPrint x
    
print "%d" 1
print "aaaa"
print "%s %s" "b" "c"

There are some examples here and here .

I couldn't find kprintf documentation, so I'm not sure that this usage is correct, but it produces the correct result for me. Another possible candidate is ksprintf , which also produces the same result.

Answer 2

You can use the same signature as sprintf:

let print (format : Printf.StringFormat<'T>) =
    sprintf format
    |> dosomethingElse

and you can use it as you want:

print "hello"
print "the time is %A" DateTime.UtcNow