Questions tagged [f#]
F# is a succinct, expressive, and efficient functional and object-oriented language for .NET
364
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A simple functional F# wrapper for EasyNetQ
This is my first attempt at creating a small module to wrap the .NET library EasyNetQ in F# to make it more functional.
I am pretty new to F# and I would like to get feedbacks on everything: types, ...
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2
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F# wrapper to generate SHA256 signature for a file
I've created the following module to allow me to generate a SHA256 signature for a file. (In real life this is used to verify an image file hasn't been amended). The cut down code looks like this:
<...
- 507
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Roman Numbers - The Functional Way
Yet another exercise in converting values between the decimal and roman number systems.
I have tried the functional way.
Any comments are welcome - but I'm especially interested in answers focusing ...
user73941
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1
answer
46
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2
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1
answer
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F# parse data and calculate sum
I decided to play with F# and found simple task on Codewars.
The task is sounds like "Calculate Sum/Mean/Avarage for selected City".
I decided to calculate only Sum. My solution is horrific. I would ...
- 275
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answer
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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 ...
- 1,098
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answer
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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.
...
- 409
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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.
...
- 293
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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 ...
- 20k
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1
answer
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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 ...
- 20k
6
votes
1
answer
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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 ...
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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 ...
- 354
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2
answers
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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 ...
- 8,498
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votes
2
answers
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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#) ...
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0
answers
114
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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 ...
- 354
2
votes
1
answer
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 ...
- 382
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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 ...
- 382
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2
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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, ...
- 20k
6
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1
answer
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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#. ...
- 354
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0
answers
141
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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:
...
- 141
2
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2
answers
119
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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 ...
- 123
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1
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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 ...
- 571
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1
answer
317
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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 ...
- 141
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1
answer
161
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 ...
- 571
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votes
3
answers
170
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 ...
- 20k
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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:
...
- 267
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answers
83
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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 ...
- 141
5
votes
1
answer
204
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 ...
- 153
2
votes
0
answers
93
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 ...
- 571
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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 ...
- 261
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1
answer
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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 ...
- 571
7
votes
0
answers
112
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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 ...
- 571
3
votes
0
answers
108
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 ...
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1
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512
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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 ...
- 191
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votes
0
answers
62
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 ...
- 5,561
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votes
1
answer
144
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:
...
- 311
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1
answer
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.
...
user34073
3
votes
1
answer
955
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: ...
- 571
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votes
2
answers
101
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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 ...
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HTTP request call for a token
The following code seems to have several redundant Flush, Close and Abort statements despite ...
- 201
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votes
3
answers
121
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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.
...
- 351
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votes
1
answer
155
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), ...
- 123
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votes
1
answer
165
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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:
...
- 143
1
vote
1
answer
49
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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'...
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2
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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 ...
- 351
1
vote
0
answers
118
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 ...
- 571
0
votes
1
answer
975
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 ...
- 351
4
votes
1
answer
166
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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 ...
- 507
5
votes
2
answers
677
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 ...
- 20k
1
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0
answers
196
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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 ...
- 571