Macro show 

macro_rules! show {
    ($expr:expr $(, sep=$sep:expr)? $(, end=$end:expr)? $(,)? $(=> $buf:expr)?) => { ... };
    ($expr:expr, end=$end:expr $(, sep=$sep:expr)? $(,)? $(=> $buf:expr)?) => { ... };
}

Write the given expression into standard output using WriteInto.

The intended grammar is:

show!($expr:expr $(, sep=$sep:expr)? $(, end=$end:expr)? $(,)? $(=> $buf:expr)?)

You can configure the writer using the following options:

• sep: Separator between values. Default is " ". Provide an instance of Separators to use custom separators, and if it has mismatched dimensions, it may use the default separator (if there is one) or panic.
• end: End of the output. Default is "\n". Provide a string to use a custom end.
• buf: Buffer to write into. Default is standard output. Provide a mutable reference to a buffer that implements std::io::Write to write into it.

fn main() {
    use iof::show;

    // This will write "42\n" to the standard output.
    show!(42);
    // This will write "Hello, World!\n" to the standard output.
    show!("Hello, World!");
    // This will write "1 2 3 4\n" to the standard output.
    show!([1, 2, 3, 4]);
    // This will write "1 2\n3 4\n" to the standard output.
    show!([[1, 2], [3, 4]]);
    // This will write "1, 2\n3, 4\n" to the standard output.
    show!([[1, 2], [3, 4]], sep = ["\n", ", "]);
    // This will write "1, 2\n3, 4!" to the standard output.
    show!([[1, 2], [3, 4]], sep = ["\n", ", "], end = "!\n");
    // This will write "1,2;3,4!" to the standard output.
    show!([[1, 2], [3, 4]], sep = [';', ','], end = "!\n");
}