Generic `printf` implementation in Zig

printf.zig

const std = @import("std");

fn printf(comptime fmt: []const u8, args: anytype) anyerror!void {
    const stdout = std.io.getStdOut().writer();

    comptime var arg_idx: usize = 0;

    inline for (fmt) |c| {
        if (c == '*') {
            try printArg(stdout, args[arg_idx]);
            arg_idx += 1;
        } else {
            try stdout.print("{c}", .{c});
        }
    }

    comptime {
        if (args.len != arg_idx) {
            @compileError("Unused arguments");
        }
    }
}

fn printArg(stdout: std.fs.File.Writer, arg: anytype) anyerror!void {
    if (@typeInfo(@TypeOf(arg)) == .Pointer) {
        try stdout.writeAll(arg);
    } else {
        try stdout.print("{any}", .{arg});
    }
}

pub fn main() !void {
    try printf("Mr. John has * contacts in *.\n", .{ 42, "New York" });
}