file

A simple file abstraction for Carp.

Installation

You can obtain this library like so:

(load "git@github.com:carpentry-org/file@0.1.2")

Usage

The main type involved in working with this library is File, naturally. All file operations depend on the file being opened.

(File.open "example.txt") ; => a Result containing a File you can write to
(File.open-with "example.txt" "a") ; => a Result containing a File you append to

If the file couldn’t be opened due to it not existing or file permission errors, a Result.Error with an error message is returned.

The file permissions follow the file modes in UNIX. The default is "a+", or writing/reading. Generally, files have a name, mode, and file property; you can read safely from them, but writing to them directly is discouraged.

Before you end your operations on the file, it is good practice to close the file again. In Carp, we do this using close.

(close f)

You can read from the file—or read-all, if you don’t care about length—, write to it, remove it, or rewind the file buffer.

(write &f "hi")
(rewind &f)
(IO.println &(read-all &f))

All of these will check whether the files are actually readable and/or writable before performing any IO actions and return a Result.Error if they can’t.

You can also ask about the modes of the file, using the functions readable?, writable?, or binary-mode?.

And that’s about it!

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Have fun!