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How to write Monad for class MyPair[+A, +B]
I have no idea how to implement MonadError for case class MyPair[+A, +B](a: A, b: B), since I don't understand how to deal with 2 types in Monad.
I've been trying to write it for 2 weeks already, no ...
Best practices
3
votes
4
replies
107
views
Functional pattern, good or bad?
When writing modules, i am always struggling trying to identify the related dependencies of the functions, properties, etc...
That's why i am now trying to code using only pure functions, and to ...
1
vote
1
answer
94
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How can I implement consistent typed error propagation in C# without scattering try/catch across layers? [closed]
I have a C# application with multiple layers (controllers, services, domain logic, and background workers). Error handling has become inconsistent because many methods contain their own try/catch ...
0
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0
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52
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Mutually recursive stack-safe functions with different types
I want to make my mutually recursive functions stack-safe, but because they have different signatures - one traverses a list and other a tree(?) of sorts - I'm not clear how to go about this.
Here's ...
1
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2
answers
141
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Replacing the element in the list with the specific index using `foldr` —— Exercise 1.19 of Essentials of Programming Language
Here is the question from Mitchell Wand's Essentials of Programming Language:
Exercise 1.19 [⋆ ⋆] (list-set lst n x) returns a list like lst, except that the n-th element, using zero-based indexing, ...
Advice
0
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2
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106
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How to effectively use ASP.NET core Hybrid Cache with Result<T> type
Suppose a scenario where:
you need to execute an expensive operation which can fail or succeed.
the result of the operation is modeled by using a result object Result<T>. The result object ...
Best practices
5
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3
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154
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Is there a way to tuck in Ord inside Applicative?
I had a nice idea of using applicative for nondeterministic financial modelling. Or maybe it is a simple case of sentization. So the basic example is to define newtype ValueRange.
newtype ValueRange a ...
0
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1
answer
96
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How to split a shell command into tokens in a quote-aware fashion? [closed]
The task
Given the following string1
one ' two 'three four
the required function should split it in 3 tokens (one, two three, and four), in agreement with how the bash shell does:
$ function ...
0
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1
answer
128
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What's the idiomatic/correct way to split a string into its first word and the rest of the string? [closed]
tl;dr
Ideally, I'd want the following
"hello world" is split in "hello" and " world"
" world" is split in "" and " world"
"hello "...
4
votes
1
answer
119
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Understanding usage of withFileBlocking with named pipes
The following program
assumes that /path/to/mypipe is a named pipe, e.g. created via mkfifo /path/to/mypipe, with no readers/writers waiting yet,
runs two threads, of which
the main thread keeps ...
3
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2
answers
157
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Functional core - Imperative shell: dealing with logic dependant on conditional & expensive IO operations
tldr; how does one deal with logic that depends on data that are too heavy to fetch up-front when subscribing to the functional core, imperative shell line of thought?
Years ago I was inspired by Gary ...
3
votes
2
answers
108
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Why doesn't readFile block on unix pipe in which no write has happened yet?
If in a terminal I enter
mkfifo /tmp/pipe
echo hello > /tmp/pipe
(which blocks) and in another I run the haskell program
main = readFile "/tmp/foobar" >>= putStr
then I see it ...
2
votes
1
answer
88
views
What does it mean that the arguments to <*> and their associated effects are known statically?
I'm reading the paper Selective Applicative Functors. So far I've read from page 16 out 29, and I think I've understood the gist of this abstraction, but I'm having some trouble with some basic ...
1
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2
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237
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How can I transform large nested PHP arrays immutably without creating expensive deep copies?
I’m working with large nested associative arrays in PHP and I need to apply transformations (like map, filter, reshape) immutably, meaning the original array should not be modified.
The problem is ...
1
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0
answers
121
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How to parametrize a loop body with a function while guaranteeing performance?
Consider the following toy code which performs very simple (a few instructions) operations on a hot loop over a large amount of values:
template<float (*f)(float)>
void process_f(int count, ...