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dropAt :: Int -> [a] -> [a]
dropAt = go id
  where
    go :: ([b] -> [b]) -> Int -> [b] -> [b]
    go f n [] = f []
    go f 0 (x:xs) = f xs
    go f n (x:xs) = go (f . (x:)) (n-1) xs

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{-# LANGUAGE OverloadedStrings #-}

import Control.Concurrent.Async
import Control.Concurrent.QSem
import Control.Monad
import Control.Monad.Catch
import Control.Monad.Trans
import Control.Monad.Reader

import Data.ByteString.Lazy (ByteString)

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{-# LANGUAGE ScopedTypeVariables #-}
module Main where

import Control.Monad (forM_)
import Data.Maybe (fromMaybe)

generalisedFizzBuzz
    :: forall a f m
     . (Foldable f, Semigroup m)
    => (a -> m) -> (a -> a -> Bool) -> f (a, m) -> a -> m

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Why You Should Stop Saying "Concrete Type"!

TL;DR: There is no concrete (hah!) definition of "concrete type", different people are meaning different things by those words and assuming everyone else means the same thing.

A Quick Type Primer

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The Cabal/Stack Disambiguation Guide

One of the most frequently asked Haskell beginner questions in recent years is:

"Stack or cabal?"

I will helpfully not answer this question. Instead I will hope to eliminate the confusion that many of the askers seem to have about the various different

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#include <stdio.h>

char X = 'a';

int main(int argc, char* argv[])
{
    (void) argc;
    (void) argv;

    struct X {

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import Foreign

main :: IO Int
main = peek nullPtr