ioanaci

    const std = @import("std");
    
    fn get_value(comptime b: bool) if (b) u32 else []const u8 {
        if (b) return 12
        else return "string";
    }
    
    fn do_thing(b: bool) void {
        switch (b) {
            inline true => |known_b| std.log.info("{d}", .{get_value(known_b)}),
            inline false => |known_b| std.log.info("{s}", .{get_value(known_b)}),
        }
    }
    
    pub fn main() void {
        do_thing(true);
        do_thing(false);
    }

    fn pick_type(comptime b: bool) type {
        if (b) return u32 else return []const u8;
    }

    fn get_value(comptime b: bool) pick_type(b)

    fn do_thing(b: bool) void {
        inline for (0..2) |i| { // go through all bool variants
            const known_b = (i != 0);
            
            if (known_b == b) {
                // Essentially what we have now is a known_b which is proven
                // at compile-time to be equal to whatever runtime b we have.
                // So we're free to do any kind of dependent type things we'd like
                // with this value.
                
                const value = get_value(known_b);
                // Here we know the type of value but it still depends on the runtime b.
                
                if (known_b) std.log.info("{d}", .{value}) // treated as an int
                else std.log.info("{s}", .{value}); // treated as a string
                
                // We can also just decide based on the type of value at this point.
                if (@TypeOf(value) == u32) ... else ...;
                // Or, a switch
                switch (@TypeOf(value)) {
                    u32 => ...,
                    []const u8 => ...,
                }
            }
        }
    }