Re: Invalid read syntax for compiled bool vector

[Richard Stallman]

    Apparently, you have to bind coding-system-for-write before writing a
    source file with a literal bool-vector constant in it, or else Emacs
    will either ask the user for the coding system, or write the file
    using some default coding system which may not do the right thing.

I guess we should change the syntax for bool-vectors
so as to put just 4 bits into each character.
The question is how to do that in a somewhat compatible way.