It’s the function composition operator.
More info on Chris Smith’s blogpost.
Introducing the Function Composition
operator (>>):
let inline (>>) f g x = g(f x)
Which reads as: given two functions, f
and g, and a value, x, compute the
result of f of x and pass that result
to g. The interesting thing here is
that you can curry the (>>) function
and only pass in parameters f and g,
the result is a function which takes a
single parameter and produces the
result g ( f ( x ) ).Here’s a quick example of composing a
function out of smaller ones:
let negate x = x * -1
let square x = x * x
let print x = printfn "The number is: %d" x
let square_negate_then_print = square >> negate >> print
asserdo square_negate_then_print 2
When executed prints ‘-4’.