This is common in many functional languages, and even in the shell. Think of pipes such as input | sed ... | grep ..., or in F#, xs |> List.map (fun x -> x.Valu

This is common in many functional languages, and even in the shell. Think of pipes such as input | sed ... | grep ..., or in F#, xs |> List.map (fun x -> x.Value). Basically, each input goes into the function and is piped through to get to the output.