I have the following sample that finds the numbers in s1 that are not in s2. let s1 = seq { 1..3 } let s2 = seq { 3..4 } s1 |> Seq.filter (fun x -> s2 |> Seq.forall (fun y -> x <> y)) |> Seq.iter (fun x -> printfn $"{x}") This prints 1… Read More Can an F# query expression filter for items that are NOT in a sub-query?
The following 2 functions let episodeDict1 (a: obj) = match a with | 😕 (Episode -> _) as generator -> let episodes = [D; W; M] let values = episodes |> List.map generator List.zip episodes values | 😕 _ as value -> [D, value; W, value; M, value] |> dict |> Dictionary let episodeDict2: obj… Read More F# 'function' functions cannot inline
Say I have a basic function, like: let double x = x * 2 Since I know the types, I can convert it into a Func<_,_> explicitly, which can then be used as a Delegate: let doubleFuncExplicit = Func<int, int>(double) However, when I attempt to do this by using Activator.CreateInstance() instead of the constructor, like… Read More F# – how can I convert an F# function into a System.Delegate using reflection?
i have simple struct [<Struct>] type Phone = private Phone of string and i need cast to Phone voption let toVOption (phone: string) : Phone voption = phone |> ValueOption.toObj end i see error Type mismatch. Expecting a ‘string -> Phone voption’ but given a ”a voption -> ‘a’ The type ‘string’ does not match… Read More How cast string to voption struct?
I write most of my backend code in F# – but my WPF project is in C# and I am wiring up progress reporting between the process and UI. My F# Code type DownloadProgressModel = { mutable PercentageComplete: int totalOrders: int mutable orderPosition: int } let doMockDownload(progress: IProgress<DownloadProgressModel>) = async { let downloadprogress: DownloadProgressModel =… Read More How to Await F# Async Code Method from C# ( WPF )
The following code is from chapter 5 of "F# 4.0 Design Patterns". let a = 1,"car" type System.Tuple<‘T1,’T2> with member t.AsString() = sprintf "[[%A]:[%A]]" t.Item1 t.Item2 (a |> box :?> System.Tuple<int,string>).AsString() The desired output is [[1]:["car"]] However, a red squiggly appears under AsString(). "The field, constructor or member ‘AsString’ is not defined. Maybe you want… Read More How to do tuple augmentation
I have made the following line of code : DF.groupby(["Name"], as_index=False).agg({"A": lambda x:sum(abs(x)) ,’B’: ‘first’}).round(2) with a DF output : Name A B Test 6 3 Test -3 Gives the following output : Name A B Test 9 3 How would I do to get the following output : Name A B Test 9 1… Read More lambda function to calculate weighted average in a group by
Given the following F# snippet: type A(children: A list) = member val P1 = "" member val P2 = "" member val Children = children type B = { F1:string Children: B list } let rec f1 (a:A) = { F1 = a.P1 Children = a.Children |> List.map f1 } let rec f2 (a:A) =… Read More F# – Recursion with anonymous records
This function is supposed to just return the index of a list. That part works. However when a element is not in a list it must return -1. For some reason it does not return -1. let rec search f list = match list with | head::tail -> if f head then 0 else 1… Read More Base case not getting picked up in my F# function
My code subscribes to an event and it needs to unsubscribe (Dispose) once the event has been handled. However this looks like a chicken-egg problem. Using rec doesn’t work and I cannot find how to do it. It there any well-konwn pattern to bypass this limitation? let process = new Process() let exitSubscription = process.Exited.Subscribe… Read More How to unsubscribe an event from inside the event handler?