Questions tagged [f#]
F# is a succinct, expressive, and efficient functional and object-oriented language for .NET
359
questions
2
votes
1answer
86 views
Project Euler Problem #102 in F#: counting triangles that contain the origin
I've recently decided to get into functional programming with F#, and decided to learn the language through Project Euler. The following is my implementation of problem 102:
Problem:
Three ...
3
votes
1answer
247 views
Convert bitcoin value based on exchange rate from JSON API
I’m learning F# and trying to find a more ‘functional’ way to code a simple program that retrieves the price of BTC and calculates the EUR value of an amount of Bitcoin.
...
2
votes
0answers
46 views
Creating idiomatic and efficient method to stream large JSON file
The purpose of the code is to efficiently stream JSON items from a large file.
I am wondering if this is efficient and decently idiomatic. Not sure how I could eliminate the while loop either.
...
4
votes
1answer
58 views
Analyzing spoke overlaps during rotation: Round 2
Round 1: Analyzing spoke overlaps during rotation
I previously posted this question, but I've changed a lot of the code since then.
There was a mention of the previous being a bit mixed up, and things ...
6
votes
1answer
60 views
Analyzing spoke overlaps during rotation
For a personal project that I've recently started I have to analyze the rotation of two shapes with sets of spokes, where the spokes are evenly-spaced, and split into a given number.
That is, if I ...
6
votes
1answer
89 views
Verifying that three cards make a "Set"
The game of Set involves cards with four properties: number, symbol, shading, and colour.
Three cards make a "Set" if the property is either all the same or all different across the three cards, for ...
1
vote
0answers
46 views
Blockchain implementation in F#: Wallet
Introduction
This is Part 3 of my F# blockchain implementation. Previous parts:
Block and Blockchain
Transactions
Code
In this part I am implementing a wallet functionality. The code is based on a ...
3
votes
2answers
596 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
289 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
104 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
42 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
331 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
99 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
446 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
134 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
112 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
296 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
307 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
155 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
168 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
78 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
186 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
84 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
449 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
163 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
109 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
107 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
478 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
56 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
107 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
875 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
100 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
39 views
HTTP request call for a token
The following code seems to have several redundant Flush, Close and Abort statements despite ...
2
votes
3answers
116 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
153 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
159 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
49 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
359 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
113 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
890 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
146 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
609 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
191 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
133 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
151 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
104 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
168 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.
...