Questions tagged [f#]
F# is a succinct, expressive, and efficient functional and object-oriented language for .NET
352
questions
3
votes
2answers
589 views
Advent of Code 2018 day 1 part 2: find the first aggregated number that occures twice
I am using the coding puzzels of https://adventofcode.com for improving my F# skills.
Problem:
Day 1 Part 2:
Starting with frequency 0, a list of numbers should be added successive generating new ...
8
votes
2answers
279 views
Conway's Game of Life F#
I am a C# developer learning F#. Would appreciate any suggestions on how this code can be improved. Main points I am interested in:
Functional style of the code, absense of imperative style(C#) ...
1
vote
0answers
89 views
Blockchain implementation in F#: Transactions
Introduction
This is Part 2 of my F# blockchain implementation. Previous parts:
Block and Blockchain
Code
This time I am tackling transactions. The code is based on a JavaScript blockchain ...
2
votes
1answer
41 views
Connect elements of a list to elements of an other list using a two-dim array
Story:
I build a kind of labyrinth. This labyrinth is divided in seven steps. You start with the first, then second, and so on to the seventh. You cannot go back to a previous step. Each step ...
5
votes
0answers
303 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 ...
5
votes
2answers
97 views
Encoding and decoding log entries in a Lossy Binary Format
One of the projects I'm working on requires logging a huge amount of information (basically, every function call). The problem is obviously that logging a lot of information has a few side-effects, ...
6
votes
1answer
368 views
Blockchain implementation in F#: Block and Blockchain
Some time ago I started writing a blockchain implementation for learning purposes. I used this article as reference. Originally I wrote the code in C# but recently I have rewritten everything to F#. ...
2
votes
0answers
127 views
Lexer function to handle the '/' character
I'm writing a toy compiler, which is in a very early stage of development. The lexer contains the following block of code:
...
2
votes
2answers
109 views
Sorting a list into different bags according to predicate
I've just started with F# (I'm coming from a mostly OO background) and I'm looking for
feedback on the code, particularly: is this the way F# code should be written like?
have I overlooked an ...
5
votes
1answer
265 views
F# Idiomatic Log4Net Wrapper
I put together a log4net wrapper that more closely resembles F#-idiomatic logging functions. The basic idea is that there's a Log module that defines a set of 8 ...
2
votes
1answer
286 views
Roslyn analyzer, converted from C# to F#
I'm learning F# and for an exercise, I took a roslyn analyzer in C# and ported it to F#.
In the excerpt below the GetParameterInfo function:
takes in ...
5
votes
1answer
148 views
Async/Await Computation Expression
When writing asynchronous code in F#, one often needs to call methods in the .NET BCL that return Task or Task<T> rather ...
10
votes
3answers
166 views
Generating image gauges from a value, min and max
One of the things I was recently investigating was the ability to generate "gauge" charts—that is, a chart which shows where a value stands within a range of values.
As an example, if we know ...
5
votes
3answers
2k views
Implementing class equality/comparison in F#
I'm working on some book material on classes and interfaces in F#. My example is a latitude/longitude class:
...
4
votes
0answers
74 views
Hierarchy (Family Tree) Domain Model
I'm wanting to model a family tree in the F# type system. The basic requirements:
A family tree is made up of family members
A ...
5
votes
1answer
170 views
Simulating coin flips and plotting a histogram
I started playing around recently with F# and I find it quite elegant and succinct language.
A common problem I like to solve in every language I start to learn is the coin flip problem, with the ...
2
votes
0answers
77 views
Business Rule DSL for Values in Domain-Driven Design
Following the patterns from the book Domain Modeling Made Functional, I am implementing a single-case union for the simple values in my domain model instead of using primitives. The union cases have ...
5
votes
0answers
435 views
Backtracking solver for n queens problem and knight's tour
Playing with https://ocaml.org/learn/tutorials/99problems.html#Miscellaneous-Problems I wrote a backtracking solver for the n queens problem, then the knight's tour, and realised I could generalise ...
4
votes
1answer
149 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 ...
7
votes
0answers
107 views
Agent-based Immutable Map
I am in the process of removing the last few pieces of mutable state from an F#-based distributed system. Some of the remaining mutable state is a ...
3
votes
0answers
106 views
Queue-based fixed-duration memory cache
I used to use the MemoryCache in .Net but recently read about a DB using using a linked-list, which only had to check the prefix of the list in \$O(1)\$ complexity, to time values out, as opposed to ...
8
votes
1answer
414 views
F# Either computation expression with while loop
I want to implement an Either computation expression in F#. The computation executes a function inside a while loop, and this function's return type is ...
2
votes
0answers
55 views
Work environment simulator
This code attempts to solve a suggested challenge by myself a while back on meta, transcribed here for simplicity.
Allocate resources efficiently on a work environment
The company Code42Review ...
4
votes
1answer
91 views
Pair up elements of a sequence without overlap
I have a sequence (in this case actually an array) like this:
[| 1; 2; 3; 4; 5; 6; 7; 8; 9; 10|]
And want to produce a sequence of pairs like this:
...
2
votes
1answer
106 views
Is It In Its Prime?
Just because I'm bored, I wrote yet another prime number generator. I think it's pretty clean, but I won't be surprised if someone finds something to comment on.
...
3
votes
1answer
685 views
AutoMapper DSL (Computation Expression) for F#
I have created a DSL for AutoMapper using an F# Computation Expression Builder. The Computation Builder itself is fairly simple, and effectively defines 5 basic operations: ...
6
votes
2answers
98 views
12 Days of Christmas with F#
I've implemented 12 Days of Christmas just by using pattern matching. It's not very efficient as it performs 12 iterations, each performing its own iteration (potentially from 12 down to 1... does ...
1
vote
0answers
38 views
HTTP request call for a token
The following code seems to have several redundant Flush, Close and Abort statements despite ...
2
votes
3answers
115 views
Implementation of Permutation Algorithm B from Topor, 1982
This is Algorithm B from Functional Programs for Generating Permutations (Topor, 1982).
We have implemented Algorithm B in an F# recursive module as follows.
...
2
votes
1answer
150 views
Mocking an F# primality tester
I would like to ask 2 questions about the modularization of an F# file. The code is just a working example of prime factorization, but that's not the main topic. I have a main file (PrimeFactors.fs), ...
4
votes
1answer
147 views
FizzBuzz in F# with functional programming
Learning F#, created a somewhat elaborate fizzbuzz-builder implementation to see if I'm starting to "get" F# and thinking functionally:
...
1
vote
1answer
47 views
Inspectors & Deconstruction on Unions in a list
I am still new to functional programming and found myself trying to filter and map a list of discriminating unions. I could be wrong, but it started to feel very unnatural to do this. I just couldn'...
5
votes
2answers
347 views
Implementation of Permutation Algorithm A from Topor, 1982
This is Algorithm A from Functional Programs for Generating Permutations (Topor, 1982). The author states that the algorithm was described in TAoCP Vol 1.
We have implemented Algorithm A in F# as ...
1
vote
0answers
108 views
Immutable Queue with Bulk-Enqueue
I recently needed a data structure with FIFO queue semantics that supported efficient bulk-insertion (often need to enqueue thousands of messages at once). I took a look at Purely Functional Data ...
0
votes
1answer
773 views
Count the number of digits in an integer using F# and log10
This code counts the number of digits in an integer.
let digitCount number = (int) (log10 ((float)number)) + 1;
For instance, it tells us ...
4
votes
1answer
121 views
Generating the Collatz sequence in F#
Below is my code for building the collatz sequence so a given number. I'm trying to make the function tail recursive and I believe that this impelemtation is tail recursive but I'm not yet so ...
5
votes
2answers
542 views
Generating abbreviations for strings
One of many aspects of a project I am responsible for is generating an abbreviation, that is no more than n characters, for a given string. We use this in the ...
1
vote
0answers
185 views
F# Operation Framework (Railway-Oriented Programming + Task/Async/Lazy)
I recently published the initial version of what is effectively my first open-source software package, a Railway-Oriented Programming Framework for F# that encapsulates Tasks, Async Workflows, and ...
1
vote
0answers
121 views
Thread-safe hashset that enumerates according to insertion order
According to the .NET documentation, HashSet<T> does not maintain order when enumerated so I implemented my own using F#.
Can anyone help review if this is ...
6
votes
1answer
149 views
Finding the first position in a number spiral that's bigger than a target
I'm working on day 3.2 of Advent of Code.
The task for this challenge is to create a number spiral where each element is the sum of all of its neighbors. Using this spiral, we have to find the first ...
1
vote
0answers
49 views
Creating and manipulating a map for a text based game F#
I have put my whole code so far below, but what I am most interested in is how best to implement the map and utilise it. Any tips on organising my code and keeping it clean would also be greatly ...
1
vote
0answers
101 views
F# Finding the powerset of a set
I have this function which takes a list as input and computes the powerset.
...
5
votes
1answer
163 views
Brainfuck interpreter in F# (by a C# developer)
I'm a C# developer learning F#. I have a lot of questions about practices and principles within the code. I would like to know what a "native" F# developer would've done differently.
...
4
votes
3answers
693 views
Partitioning a list in F# based on whole group characteristics
I only started programming in F# yesterday, so I've not yet discovered what idiomatic F# actually looks like.
The first task I set myself required partitioning a list into smaller lists but where the ...
0
votes
1answer
91 views
F# functions implementing polynomial arithmetic [closed]
I have a couple of functions for doing basic arithmetic on polynomials.
...
3
votes
1answer
74 views
Area under curve and its volume as solid of revolution
I would like to know if there is some more "elegant" way to write these 3 functions. Any tip or idea is welcome.
...
6
votes
2answers
685 views
Validate a password mostly to NIST-2017 standards
I have an application that needs to validate user passwords to a very reasonable custom validator, which is heavily based on NIST-2017 requirements. The validator intends to satisfy the following ...
3
votes
0answers
155 views
F# Observable.subscribeWeakly implementation
In this SO question I needed an observable subscription function that can be used kind of like Observable.subscribe, but that does not keep a strong reference to ...
8
votes
2answers
123 views
Wordpress RSS Parser
Follow Up to my earlier question.
This is an RSS Parser intended only to parse the feed Wordpress provides (and even then, only what I actually want to display on my website). ...
5
votes
1answer
262 views
RSS Parser for Blog Feed
I'm building an RSS feed parser so, later, I can retrieve recent blog posts on my word press blog and display recent posts on my other website. This code isn't intended to implement the full RSS spec. ...
