Copies from one handle to another in raw mode (using hGetContents).

Copies from one handle to another in raw mode (using hGetContents). Takes a function to provide progress updates to the user.

Copies from one handle to another in text mode (with lines). Like hBlockCopy, this implementation is nice:

hLineCopy hin hout = hLineInteract hin hout id

Copies from stdin to stdout using lines. An alias for hLineCopy over stdin and stdout.

Copies one filename to another in text mode.

Please note that the Unix permission bits are set at a default; you may need to adjust them after the copy yourself.

This function is implemented using hLineCopy internally.

Given a list of strings, output a line containing each item, adding newlines as appropriate. The list is not expected to have newlines already.

Given a handle, returns a list of all the lines in that handle. Thanks to lazy evaluation, this list does not have to be read all at once.

Combined with hPutStrLns, this can make a powerful way to develop filters. See the lineInteract function for more on that concept.

Example:

main = do
       l <- hGetLines stdin
       hPutStrLns stdout $ filter (startswith "1") l

This is similar to the built-in interact, but works on any handle, not just stdin and stdout.

In other words:

interact = hInteract stdin stdout

Line-based interaction over arbitrary handles. This is similar to wrapping hInteract with lines and unlines.

One could view this function like this:

hLineInteract finput foutput func =
    let newf = unlines . func . lines in
        hInteract finput foutput newf

Though the actual implementation is this for efficiency:

hLineInteract finput foutput func =
    do
    lines <- hGetLines finput
    hPutStrLns foutput (func lines)

Line-based interaction. This is similar to wrapping your interact functions with lines and unlines. This equality holds:

lineInteract = hLineInteract stdin stdout

Here's an example:

main = lineInteract (filter (startswith "1"))

This will act as a simple version of grep -- all lines that start with 1 will be displayed; all others will be ignored.

Applies a given function to every item in a list, and returns the new list. Unlike the system's mapM, items are evaluated lazily.

Sets stdin and stdout to be block-buffered. This can save a huge amount of system resources since far fewer syscalls are made, and can make programs run much faster.

Sets stdin and stdout to be line-buffered. This saves resources on stdout, but not many on stdin, since it it still looking for newlines.