FSharp Flexibility

flex.fs

// A case for FSharp: Flexibility Applied
// --------------------------------------
//
// Consider a Where expression in C#
// nums.Where(x => 0 <= x); //yoda-esque
//
// Let's see F# doing this.

let nums = [-2 .. 2];;

// Take 1: one to one translation of c#

nums |> Seq.filter (fun x -> 0 <= x);;

// Take 2: eliminate yoda (still possible in c#)

nums |> Seq.filter (fun x -> x >= 0);;

// Take 3: eliminate lamda with <= function and partial application

nums |> Seq.filter ((<=) 0);;

// Take 4: use language-orientation for expressiveness

let removeAll = Seq.filter;;
let lessThan = (<=);;

nums |> removeAll (lessThan 0);;

The last one is not really right.

• lessThan 0 4 returns true.
• removeAll removes all elements where the predicate is false (??)

So let's fix this:

let removeAll f = Seq.filter (f >> not)
let lessThan = (>)

let nums = [-2 .. 2]

nums |> removeAll (lessThan 0) |> printfn "%A"

You're right. I quickly hacked this together before leaving to lunch. Should've better not done this.