It’s possible to use function composition and modify the type of value returned.  Consider the following equation:

1/4x²

I might encode the function to calculate this like so:

let square x = x * x

//Want this to be a float because if this is an int division

// it will always round to 0 if x is greater than 1.

let recip x = 1.0/x

let myFunc =  fun x -> 4* (square x) >> recip

This function composition will not work because I need to pass a float to recip. But I can make it work by doing this:

let square x = x * x

let recip x = 1.0/x

let myFunc = fun x -> 4* (square x) >> float >> recip

There’s a great deal more information on conversion functions in F# here.