F# Standard Builder Methods (Template)

Builder.fsx

// stolen from: https://fsharpforfunandprofit.com/posts/computation-expressions-builder-part6/

type WhateverBuilder() =

    member this.Bind(m, f) = m f

    member this.Return(x) = x

    member this.ReturnFrom(x) = x

    member this.Yield(x) = this.Return (x)

    member this.YieldFrom(x) = x
    
    member this.Zero() = this.Return ()

    member this.Delay(f) = f

    member this.Run(f) = f()

    member this.While(guard, body) =
        if not (guard()) 
        then this.Zero() 
        else this.Bind( body(), fun () ->
            this.While(guard, body))  

    member this.TryWith(body, handler) =
        try this.ReturnFrom(body())
        with e -> handler e

    member this.TryFinally(body, compensation) =
        try this.ReturnFrom(body())
        finally compensation() 

    member this.Using(disposable:#System.IDisposable, body) =
        let body' = fun () -> body disposable
        this.TryFinally(body', fun () -> 
            match disposable with 
                | null -> () 
                | disp -> disp.Dispose())

    member this.For(sequence:seq<_>, body) =
        this.Using(sequence.GetEnumerator(),fun enum -> 
            this.While(enum.MoveNext, 
                this.Delay(fun () -> body enum.Current)))