medigor

using System;
using System.Threading.Tasks;

namespace System.Collections.Concurrent
{
    public static class ConcurrentDictionaryExtensions
    {
        /// <summary>
        /// Provides an alternative to <see cref="ConcurrentDictionary{TKey, TValue}.GetOrAdd(TKey, Func{TKey, TValue})"/> that disposes values that implement <see cref="IDisposable"/>.
        /// </summary>

medigor

// General hints on defining types with constraints or invariants
// 
// Just as in C#, use a private constructor 
// and expose "factory" methods that enforce the constraints
//
// In F#, only classes can have private constructors with public members. 
//
// If you want to use the record and DU types, the whole type becomes
// private, which means that you also need to provide:
// * a constructor function ("create").

medigor

Quick notes on a rant

Some examples related to my tweet rant https://twitter.com/dsymetweets/status/1294276915260522496

1. Implicitly discarding information is so 20th Century

In project programming this hit me this week with a bug:

medigor

type StepfulBuilder() =
    member _.Zero() = ()
    member _.Yield x = x
    
    [<CustomOperation("toInt")>]
    member inline _.ToInt(_, value) =
        int value
        
    [<CustomOperation("transform")>]
    member _.Transform(x, f) =

medigor

type EventStream<'T> ()=
    let evt=Channel.CreateUnbounded<'T>()
    let writer = evt.Writer
    let reader = evt.Reader

    let mutable key = 0

    let mutable subscriptions = Map.empty : Map<int, IObserver<'T>>
    let thisLock = new obj()
    let obs =

medigor

#r @"C:\Users\ayrat.hudaygulov\.nuget\packages\fsharp.compiler.service\26.0.1\lib\net45\FSharp.Compiler.Service.dll"

open System.IO
open Microsoft.FSharp.Compiler.Ast
open Microsoft.FSharp.Compiler.SourceCodeServices

let parse text =
    let fileName = "whatever.fs"
    let checker = FSharpChecker.Create()
    let opts = 

medigor

(*
WHAT'S GOING ON HERE?!

Sometimes you don't care about a particular type, you're interested in one field only, let's say `EntityId`.
Instead of using interface (which isn't even possible if don't own a type),
we can do structural typing in F# using SRTP and Active Patterns.
Active patterns are not required for this, but they do make code much easier to use.
*)
// So we have 2 types with field `EntityId: string`: