So I have some time off and I'm relearning Haskell, and part of the charm was coming back to cute recursive, lazy, infinite definitions like this: fibSequence :: [Integer] fibSequence = 0 : 1 : zipWith (+) fibSequence (tail fibSequence) which is a pretty good way to define the Fibonacci sequence. And then I was looking around and watching this video, which is really fun, which gives primeSequence :: [Integer] primeSequence = sieveOfEratosthenes [2..] sieveOfEratosthenes :: [Integer] -> [Integer] sieveOfEratosthenes (p:ps) = p : sieveOfEratosthenes [ x | x <- ps, x `mod` p /= 0] And I was like OMG GENIUS! Nice. And then later I tried using this to solve problems in Project Euler, and realized quickly that this indeed is NOT the proper sieve of Erastosthenes, because it does multiple cancellations for each number. So I had to go down a rabbit hole, which has shown me that truly lazy infinite structures are VERY HARD TO WRITE.

Hi, I'm learning Haskell, and I admit I'm just playing with it right now. While I'm not a terribly experienced programmer, I do have a Bachelor's in Computer Science. My professional experience has been restricted to mostly web development in Typescript sadly. I have not touched functional programming, but this seems unrelated to functional intricacies and more me having a primitive understanding of number types. I'm playing with pattern matching and guards so maybe excuse the silly code, I'm just starting. I try loading (":l haskell_test.hs") my file in GHCi and get the following compile error "Could not deduce ‘RealFrac a’ arising from a use of ‘floor’ from the context: Num a" . I take in type Num, and floor doesn't like that general of a type, I take it? -- testing pattern matching and guards isXFactorOfY :: Num a => a -> a -> Bool isXFactorOfY 0 0 = True isXFactorOfY 0 y = False isXFactorOfY x 0 = False isXFactorOfY 1 1 = True isXFactorOfY 1 y = False isXFactorOfY x 1 = False isXFactorOfY x y | x > y = False | abs(x / y) > floor( abs(x)/abs(y) ) = False | otherwise = True I've tried replacing Num a with Real a, RealFrac a, and some other things I've seen. But I'm just poking blindly and don't actually understand the exact issue. I'd like some help understanding it explicitly rather than stumbling upon the compile-able code. I see the reference for floor is here: https://hackage.haskell.org/package/ClassyPrelude-0.1/docs/Prelude-Math.html#v:floor I guess I'm confused what it want's floor to take in, I figured any number that's an Int or Float would work. But I'm not sure how to define that the way it wants. Again sorry for the silly code. I am quite rusty and am having a rough time getting back into .... problem solving, and reading APIs and references it seems. Thank you in advance for any help or direction you give. The full compile error output is as follows: ghci> :l haskell_test.hs [1 of 2] Compiling Main ( haskell_test.hs, interpreted ) haskell_test.hs:3:14: error: [GHC-39999] • Could not deduce ‘Eq a’ arising from the literal ‘0’ from the context: Num a bound by the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool at haskell_test.hs:2:1-39 Possible fix: add (Eq a) to the context of the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool • In the pattern: 0 In an equation for ‘isXFactorOfY’: isXFactorOfY 0 0 = True | 3 | isXFactorOfY 0 0 = True | ^ haskell_test.hs:9:29: error: [GHC-39999] • Could not deduce ‘Ord a’ arising from a use of ‘>’ from the context: Num a bound by the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool at haskell_test.hs:2:1-39 Possible fix: add (Ord a) to the context of the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool • In the expression: x > y In a stmt of a pattern guard for an equation for ‘isXFactorOfY’: x > y In an equation for ‘isXFactorOfY’: isXFactorOfY x y | x > y = False | abs (x / y) > floor (abs (x) / abs (y)) = False | otherwise = True | 9 | isXFactorOfY x y | x > y = False | ^ haskell_test.hs:10:33: error: [GHC-39999] • Could not deduce ‘Fractional a’ arising from a use of ‘/’ from the context: Num a bound by the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool at haskell_test.hs:2:1-39 Possible fix: add (Fractional a) to the context of the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool • In the first argument of ‘abs’, namely ‘(x / y)’ In the first argument of ‘(>)’, namely ‘abs (x / y)’ In the expression: abs (x / y) > floor (abs (x) / abs (y)) | 10 | | abs(x / y) > floor( abs(x)/abs(y) ) = False | ^ haskell_test.hs:10:40: error: [GHC-39999] • Could not deduce ‘RealFrac a’ arising from a use of ‘floor’ from the context: Num a bound by the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool at haskell_test.hs:2:1-39 Possible fix: add (RealFrac a) to the context of the type signature for: isXFactorOfY :: forall a. Num a => a -> a -> Bool • In the second argument of ‘(>)’, namely ‘floor (abs (x) / abs (y))’ In the expression: abs (x / y) > floor (abs (x) / abs (y)) In a stmt of a pattern guard for an equation for ‘isXFactorOfY’: abs (x / y) > floor (abs (x) / abs (y)) | 10 | | abs(x / y) > floor( abs(x)/abs(y) ) = False | ^^^^^ Failed, unloaded all modules.

The question explains itself, but for context: I am writing an Over-Engineered HTTP server for fun's and learning's sake, and I have hit a conceptual roadblock. Currently, the server works thusly: One (1) thread sits on a port and accept()s incoming requests and adds them to a queue, then pthread_cond_signal()s a condition that... ... Four (4) threads (request handlers) are pthread_cond_wait()ing on, one of whom will pick up the request and parse it. Here comes the issue: Similar to that the server simply adds each request to a queue, I want each request handler to, once it's parsed a request, hand it off to some HTTP_<method> function, then pick up the next request from the queue, only returning to the original point of execution (the point where HTTP_<method> was called), where it then returns a response. The only two ways that comes to mind of doing this, one of them require N more threads sitting on another queue, which I feel weird about, and the other requires some Macro Fuckery that I found on a Github repository then lost, so Idk if it even is feasible. How do I go forward from here? TL;DR: Async Await for C; good, bad, or disgustingly ugly? Potential other solutions?

Hi everyone, I’m CuriousExplorer99. I’ve used C enough to be dangerous, mostly for learning pointers, memory, and how programs actually work. Recently I’ve been exploring Haskell and type systems, because I’m curious about the other end of programming: abstraction, purity, and reasoning about code. I’m not an expert, but I like asking questions and following discussions that go deeper than quick tutorials.