get-apld-finkel.hs

#! /usr/bin/env nix-shell
#! nix-shell -p "haskellPackages.ghcWithPackages (pkgs: with pkgs; [http-conduit http-types bytestring])" -i runhaskell
#! nix-shell -I nixpkgs=https://github.com/NixOS/nixpkgs/archive/293a28df6d7ff3dec1e61e37cc4ee6e6c0fb0847.tar.gz

{-# LANGUAGE BlockArguments #-}
{-# LANGUAGE ImportQualifiedPost #-}
{-# LANGUAGE OverloadedStrings #-}

import Control.Monad (forM)
import Data.ByteString qualified as B
import Data.ByteString.Lazy qualified as BL
import Data.Foldable
import Data.Functor ((<&>))
import Network.HTTP.Simple
import Network.HTTP.Types

waybackUrl = "https://web.archive.org/web/20150528104756if_"
apldUrl = "http://www.nondot.org:80/sabre/Mirrored/AdvProgLangDesign"
baseUrl = waybackUrl <> "/" <> apldUrl

download :: (String, FilePath) -> IO ()
download (url, file) = do
  putStrLn $ "Downloading " <> file <> " ..."
  req <-
    parseRequest url
      <&> setRequestHeader hUserAgent ["get-apld-finkel"]
  response <- httpLBS req
  if "application/pdf" `elem` getResponseHeader hContentType response
    then BL.writeFile file $ getResponseBody response
    else putStrLn "Hmm, not a PDF"

main :: IO ()
main = do
  traverse_ (download . urlFile) $ fm [0 :: Int .. 10] \i ->
    let si = show i
     in if i < 10 then "0" <> si else si
  where
    fm = flip map
    urlFile num =
      let file = "finkel" <> num <> ".pdf"
       in (baseUrl <> "/" <> file, file)