All monads in Haskell are only monads if you exclude the weird seq combinator. This is also true for IO. Since seq is not actually a regular function but involves magic, you have to exclude it from checking the monad laws for the same reason you have to exclude unsafePerformIO. Using seq you can prove … Read more
Use System.IO.Directory.CreateDirectory Addtional note: You don’t have to check if it exists first. CreateDirectory will do the right thing regardless.
The javadoc says: Wherever possible, the methods in this class do not flush or close the stream. This is to avoid making non-portable assumptions about the streams’ origin and further use. Thus the caller is still responsible for closing streams after use.
Indeed there is a built in function, aptly named print. > print [1,2,3] [1,2,3] This is equivalent to putStrLn $ show [1,2,3].
It’s an old question, I hope you have already found a useful one. In case you didn’t, please check out the Simple Dynamic String library on github. I copy&paste the author’s description here: SDS is a string library for C designed to augment the limited libc string handling functionalities by adding heap allocated strings that … Read more
I think the answers referencing a FileChannel are on the mark . Here’s a sample implementation of an input stream that encapsulates this functionality. It uses delegation, so it’s not a true FileInputStream, but it is an InputStream, which is usually sufficient. One could similarly extend FileInputStream if that’s a requirement. Not tested, use at … Read more
I strongly suspect that’s because of the network connection or the web server you’re talking to – it’s not BufferedReader‘s fault. Try measuring this: InputStream stream = conn.getInputStream(); byte[] buffer = new byte[1000]; // Start timing while (stream.read(buffer) > 0) { } // End timing I think you’ll find it’s almost exactly the same time … Read more
Updated Response: This seems like a bug specific to Windows – http://bugs.python.org/issue1521491. Quoting from the workaround explained at http://mail.python.org/pipermail/python-bugs-list/2005-August/029886.html the effect of mixing reads with writes on a file open for update is entirely undefined unless a file-positioning operation occurs between them (for example, a seek()). I can’t guess what you expect to happen, but … Read more
As others have stated, it is because of lazy evaluation. The handle is half-closed after this operation, and will be closed automatically when all data is read. Both hGetContents and readFile are lazy in this way. In cases where you’re having issues with handles being kept open, typically you just force the read. Here’s the … Read more
The crypto/sha256 godoc actually has a snippet that shows how to do that (it’s basically the same code as James): package main import ( “crypto/sha256” “fmt” “io” “log” “os” ) func main() { f, err := os.Open(“file.txt”) if err != nil { log.Fatal(err) } defer f.Close() h := sha256.New() if _, err := io.Copy(h, f); … Read more