Why doesn’t Mojo have let (immutable data)? Just wondering
Mojo at one point did have both let and var declarations, but let was removed for the reasons described in this proposal. In short, let added some complexity to the language and was a common source of confusion, since both alias (now comptime) and let could be used to define a constant in slightly different ways. In practice,comptime can be used for many of the things that people were using let for.
In addition, immutable references (imm) are the default for function arguments and for value bindings. Those value bindings are locally immutable. Some functions return immutable references or conditionally immutable references (ref).