Questions tagged [f#]

F# is a succinct, expressive, and efficient functional and object-oriented language for .NET

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41 views

Download and parse XML data from a URL every minute with F#

The purpose This code is intended to achieve the following goals:- Create a hard coded list of lifts, this is pretty static and I add some extra info so I'm ok with this being in the code but I may ...
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1answer
48 views

F# simple monoalphabetic cipher code implementation

I am a new F# programmer, and a student in a security class. As part of my notes, I wrote a small implementation of a monoalphabetic cipher as follows: ...
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38 views

Cardinal to ordinal numbers in F# code reuse

I've been experimenting with the F# Bolero environment to learn F# a bit and I was trying to get the hang of pattern matching by generating ordinal numbers (1st, 2nd, 3rd, ...) from cardinal numbers (...
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1answer
119 views

"Rock, Paper, Scissors +" in F#

During a discussion in a development chat, a user suggested to another (in the context of C# originally), UserA: Challenge: Create an implementation of RPS, and then show how it can be extended to ...
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1answer
54 views

Retrying failed calls to a crypto exchange

This code represents logic used to retry failed calls to a crypto exchange: ...
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2answers
95 views

Simple Password Generator Feedback

This is my first major project in F#, looking for any critique on how I can make it more standard or more concise. Some things I feel like I could have done better are the command flag parsing and the ...
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1answer
70 views

Print each word of a sentence in a new line

this is my first F# program, very simple concept but took me a few minutes to get it. I'm new to functional programming so I'd appreciate if you could have a look ...
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3answers
78 views

How to refactor the boolean logic of this F# function?

I have a list of path I want to filter out. I want to keep only paths matching a specific pattern and remove all paths matching another specific pattern. To achieve this I pattern matched on each ...
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1answer
83 views

What would be this best way to show that my function can accept some specific numbers as input? [closed]

I am writing a credit card generator. I have method GenerateVisa() who will return either a 13 or 16 numbers string. This is the default value but GenerateVisa can ...
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1answer
44 views

Downloading multiple log files

This code succeeds in downloading log text files from multiple URLs. Can this be made more efficient? ...
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2answers
191 views

What would be the idiomatic F# way to write optional parameters?

In the context of a library to generate random credit card, it would be nice to let the user the possibility to set some optional options on some cards. Lets take Visa. Two lengths are available: 13 ...
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1answer
48 views

Maintaining state while walking a tree structure

The following code creates a simple tree structure and then walks through the tree looking for node with the value 9 that appears after we have seen a node with the value 1 and a node with the value 4 ...
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1answer
33 views

How to apply multiple filters in one statement

While trying to grasp the potentials of the collection features in F#, I encountered this one: ...
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1answer
161 views
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125 views

Converting a float to a fraction as a string

I was inspired by this video by Matt Parker to use the Farey Sequence to convert a float into a string representation of a fraction, how did I do? How well did I follow F# workflow and patterns (I'm ...
5
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1answer
119 views

Handling bill cancellation

I'm trying to refactor the working code below which intends to handle bill cancellation, but doesn't seem "linear" enough. ...
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92 views

How to flatten the nested try-catch block in F#?

How to flatten the nested try-catch block in F# for the following code? I am using EF Core with F#. The nested is required because I need to Rollback the transaction if there are errors in saving or ...
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1answer
140 views

Refactoring of two command handler implementations with F# in the context of event sourcing

I've written some F# code to handle commands in the context of event sourcing which works along the lines below: Read Events from a specific event store stream Build the current state in the given ...
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1answer
104 views

First-time F#: A simple Rock Paper Scissors

This is my first F# program. It's a simple Rock-Paper-Scissors implementation. I am looking for feedback of all sorts, e.g. the choice of types (e.g. List vs Array), whether there are parts that could ...
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1answer
136 views

CodeWars Deodorant Evaporator

How can I make the solution to this https://www.codewars.com/kata/5506b230a11c0aeab3000c1f/train/fsharp more "functional"? ...
4
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1answer
80 views

Return early with Error from Sequence mapping

I have put together this f# code in an attempt to solve the following problem Given a mapping operation that may not be able to return a value Cease mapping over the remaining items of a sequence if ...
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3answers
141 views

Idiomatic F# for iterating a seq and mapping whenever changes occur on a given selection

I've written a function that takes a sequence and check for every item in that sequence whether the current value a selection (obtained with a selection function) is different (or on the first ...
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1answer
52 views

F# Array with tuples or Map

I have a sample code and some question. Simple type property ...
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0answers
140 views

N-Queens Puzzle

The N-Queens puzzle can be solved in many ways. One is by a depth-first-search backtracking algorithm. Below is my generalized version using mutual recursion: ...
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2answers
94 views

Advent of Code 2019 day 2 in F#

I sped through the 5hr F# pluralsight course this week-end and thought I'd sement my learning by going through as many Advent of Code puzzles I could with this new learning. However, already on day 2 ...
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2answers
96 views

Solving the game Set in F#

I was playing the game Set online, and thought it would be a good exercise to write an F# script to find all of the sets for me. The rules of set are as follows: A SET is 3 cards for which each ...
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1answer
454 views

F# Binary Tree and Tree Traversal

So for an side exercise on exercism I implemented a BinarySearchTree. I was confident in implementing the creation of the binary tree. But I'm very unsure about the traversal of the tree. So I came ...
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54 views

Functional Dependency Injection Abstraction

The F# web-development framework Giraffe supports a functional style of Dependency Injection using a form of the Reader monad, as explained in this GitBook. I would like to use this pattern more ...
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1answer
78 views

Assigning jobs in a functional style

I'm new to F# and functional programming in general (coming from an object oriented background). I just wanted to get some criticism on an algorithm for assigning jobs to crew members. I want to be as ...
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139 views

Flashcard Website

In my endeavor to learn Angular, I've created a flashcard site with an F#/Mongo backend. As I'm new to Angular, I'm going to post everything; any and all feedback is welcome. First, some pictures of ...
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1answer
99 views

Asp.net middleware [closed]

This code is asp.net core middleware written in f# and called from c# for a blazor server-side app. How can this be made more efficient if any in regards to the async code. F#: ...
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2answers
89 views

Query a product from a list of brands

I am quite new to F# and just wrote my first program. It checks if the query exists in the brand list and returns the matching brand. Query is the string you are searching for in the brand list. So ...
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0answers
82 views

Sanitize input for a "robot on a grid" kata

I have the following piece of code which is FSI tested and works. However, I want to trim it as much as possible (not only the comments, which are there for my own future reference) and make it as ...
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2answers
9k views

Reading input from console in F# (as a sequence of lines)

Consuming input line-by-line until the end is often useful. In C# I would write the following loop: while ((line = Console.ReadLine()) != null) { // ... I ...
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2answers
1k views

Hierarchical State Machine in F#

I appreciate any feedback on where I might alter or improve my code for this project. This is an old attempt at implementing a Hierarchical State Machine in F#. I'm from a C#/OO background mostly. <...
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39 views

Photo rename by Exif date and group into folders with a threshold

I wrote this tiny F# project yesterday, but I am a bit rusty and I would like to know if there is anything I can refactor and make more elegant. ...
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229 views

F# XML Generation in .NET Core: XmlSerializer or XmlProvider

I am working on SEPA XML generator in F#. I developed two solutions that are roughly equivalent, one relies on the XmlSerializer while the other relies on ...
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1answer
177 views

Idiomatic way to write proper F# (x)unit + fsunit tests?

I am writing some unit tests using XUnit in F# and I am wondering what is the most idiomatic way in the F# sense to write them. Let's start a simple case: ...
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324 views

Creation of matrix with specific attempts at the end

What I want to do is build a Slay-the-Spire-like Map. As you can see in the following image, the map is splitted in ISteps and ...
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0answers
59 views

F#, Timer and propperly removed ElapsedEventHandler

I have a simple method that receives messages from bus, builds response and send it back, and it looks like: ...
6
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2answers
262 views

Asynchronous IBAN API with validation

I am working on an iban api which is about saving the iban of some members after (iban validation) in a database. The code is split between Domain (entities, behaviour for iban validation), Database ...
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426 views

A* Algorithm in F#

Inspired by this post I looked up A* on wikipedia and went on with my own implementation as seen below where I try to mimic the pseudocode on Wikipedia but in a recursive manner. I would like any ...
4
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1answer
161 views

Lock-free Immutable ConcurrentQueue

Similar to the code review I posted last week for an agent-based immutable replacement for ConcurrentDictionary, I have also created an agent-based immutable ...
4
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1answer
90 views

Binary Trie in F#

I have this little exercise writing a binary trie in F#. In C# it can be done in few lines, but here it became more complicated than I had expected (especially the ...
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1answer
64 views

F# Simple message reader using TCP

I have a review request about this part of the code: ...
4
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1answer
198 views

Convert to and from variable length quantities

As part of small MIDI library i've implemented the conversion of a VLQ (variable length quantity) for byte[] -> bigint and ...
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0answers
176 views

Async in Railway Oriented Programming in F#

In F# the Railway Oriented Programming pattern can be implemented synchronously using the Result<'t,'terr> type as result value for functions, so they can be ...
6
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1answer
71 views

F# pattern matching to determine the state of a bank account based on past events

I am writing an event sourced system in which I need to have the state based on the events that already occurred for a given bank account. The events are defined such as: ...
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2answers
192 views

Tcp server messenger awaiter in f#

Hi I have a simple tcp server, and that server receives messages with specific length so basically i need to wait for TcpClient to fill buffer with that amount of data, and it works. But I am not ...

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