gusty

open System.Collections.Concurrent

type T = T with static member getOrAdd (cd:ConcurrentDictionary<_,'t>) (f:_ -> _) k = cd.GetOrAdd (k, f)

let inline memoize (f:'``(T1 -> T2 -> ... -> Tn)``): '``(T1 -> T2 -> ... -> Tn)`` = (T $ Unchecked.defaultof<'``(T1 -> T2 -> ... -> Tn)``>) f

type T with     
    static member        ($) (_:obj,  _: 'a -> 'b) = T.getOrAdd (ConcurrentDictionary ())
    static member inline ($) (T, _:'t -> 'a -> 'b) = T.getOrAdd (ConcurrentDictionary ()) << (<<) memoize
    

gusty

+--------------------+--------------------+-------------------------+--------------------+
|Operation           | F#+ / F#           |F#+ Haskell Compatibility|Haskell             |
+====================+====================+=========================+====================+
|List.append         | @                  |                         | ++                 |
+--------------------+--------------------+-------------------------+--------------------+
|Function composition| f << g             | f . (g)                 | f . g              |
+--------------------+--------------------+-------------------------+--------------------+
|                    | <|                 | $                       | $                  |
+--------------------+--------------------+-------------------------+--------------------+

gusty

type A = class end
type B = class inherit A end
type C = class inherit B end
type D = class inherit C end

type IsNull = 
    inherit D
    static member inline ($) (_:A  , x  :'a when 'a : not struct) = System.Object.ReferenceEquals(x, null)
    static member inline ($) (_:B  , x  :'a when 'a : null      ) = match x with null -> true | _ -> false
    static member inline ($) (_:C  , _:D) = false

gusty

#load @".paket\load\net452\FSharpPlus.fsx"

open FSharpPlus
open System

[<AutoOpen>]
module SideEffects =
    let private r = Random()
    let printLn text = async { printfn "%s" text }
    let readLn() = async { return Console.ReadLine() }

gusty

#nowarn "0042"
let inline retype (x: 'T) : 'U = (# "" x: 'U #)

open System
type Curry =

    static member inline Invoke f =
        let inline call_2 (a: ^a, b: ^b) = ((^a or ^b) : (static member Curry: _*_ -> _) b, a)
        call_2 (Unchecked.defaultof<Curry>, Unchecked.defaultof<'t>) (f: 't -> 'r) : 'args

gusty

(* ===================================
Code from my series of posts "Six approaches to dependency injection"
=================================== *)

open System


(*
## The requirements