std/io

Standard input and output. Import with import "std/io";.

Everything here works on every backend except is_tty, which is native only. In the playground, input reads from the Standard input box.

Functions

write

void write(s: string)

Writes s to standard output. No newline is added.

io.write("no newline");
io.write(", same line\n");

print

void print(s: string)

Writes s followed by a newline. Equivalent to write(s) then write("\n").

io.print("one line");
io.print("another");

ewrite, eprint

void ewrite(s: string)
void eprint(s: string)

The same as write and print, but to standard error.

io.eprint("usage: greet <name>");

input

string? input()

Reads one line from standard input and returns it without the trailing newline. Returns none at end of input. A final line with no newline is still returned.

let line = io.input();
while (line != none) {
    io.print("read: " + line!);
    line = io.input();
}

is_tty

bool is_tty()

Returns true if standard output is a terminal, false if it is redirected to a file or pipe. Native backend only.

if (io.is_tty()) {
    io.print("interactive session");
}