I/O utilities (io)

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bring io provides logging helpers, output flushing, and line-based stdin reading. It is useful for logging during development and for simple interactive terminal programs.

A tiny program

bring io
bring Err

io::printLogln("Starting...")

var line: str, err: Err::Result = io::readLine()
if err.isErr() {
  io::printErrorLogln("Could not read input")
} else {
  io::printLogln("You typed: ", line)
}

io::flush()

Sample output (user types "hello"):

Starting...
hello
You typed: hello

printLog / printErrorLog vs built-in print / println

• io::printLog(msg) and io::printLogln(msg) — print to stdout as log messages (with optional color via the second color parameter). These are for structured logging.
• io::printErrorLog(msg) and io::printErrorLogln(msg) — print to stderr as error log messages (with optional color).
• The built-in print and println are general-purpose print to stdout, not part of the io module.

Use io module functions when you want color-tagged log output or need to flush; use print/println for simple output.

Logging examples

bring io

io::printLogln("Info: Application started")
io::printLog("Processing...")
io::printLogln(" done")
io::printErrorLogln("Error: Something went wrong")
io::flush()

Output:

Info: Application started
Processing... done
Error: Something went wrong

Common operations

Function	Returns	Description
io::printLog(msg)	—	Print a log message to stdout (no newline)
io::printLogln(msg)	—	Print a log message to stdout with newline
io::printErrorLog(msg)	—	Print an error log message to stderr (no newline)
io::printErrorLogln(msg)	—	Print an error log message to stderr with newline
io::flush()	—	Flush the stdout buffer
io::readLine()	str, Err::Result	Read a line from stdin; returns str and an error result

Reading from stdin

io::readLine() returns a tuple of str, Err::Result. Always check the error result before using the string:

bring io
bring Err

var input: str, err: Err::Result = io::readLine()
if err.isErr() {
  println("EOF or error reading input")
}
println("Input was: ", input)

Source & tests (if you have the repository)

What	Where
Module source	fw-modules/io_module/io-module.fg
Integration fixtures	tests/fixtures/LatestTests/IoModuleTests/