Quine

There are a couple of quines I wrote. Not the shortest or most code golfed implementations, but they are mine. They generally follow the same idea anyway.

Rust

Passes rustfmt and clippy::pedantic.

fn main() {
    println!("{Q}\nconst Q: &str = r{0}\"{Q}\"{0};", '#');
}
const Q: &str = r#"fn main() {
    println!("{Q}\nconst Q: &str = r{0}\"{Q}\"{0};", '#');
}"#;

The shortest implementation is fairly cool.

Zig

This one is fairly longwinded due to Zig's otherwise very nice multiline string literals syntax. Passes zig fmt. This works for 0.15.1.

pub fn main() !void {
    try o.interface.print("{s}\nconst Q =\n", .{Q});
    var it = @import("std").mem.splitScalar(u8, Q, '\n');
    while (it.next()) |l| try o.interface.print("    \\\\{s}\n", .{l});
    try o.interface.writeAll(";\nvar o = @import(\"std\").fs.File.stdout().writer(&.{});\n");
}
const Q =
    \\pub fn main() !void {
    \\    try o.interface.print("{s}\nconst Q =\n", .{Q});
    \\    var it = @import("std").mem.splitScalar(u8, Q, '\n');
    \\    while (it.next()) |l| try o.interface.print("    \\\\{s}\n", .{l});
    \\    try o.interface.writeAll(";\nvar o = @import(\"std\").fs.File.stdout().writer(&.{});\n");
    \\}
;
var o = @import("std").fs.File.stdout().writer(&.{});

Swift

No main function but different order.

let Q = #"""
print("let Q = #\"\"\"\n\(Q)\n\"\"\"#\n\(Q)")
"""#
print("let Q = #\"\"\"\n\(Q)\n\"\"\"#\n\(Q)")