I still do not fully understand sets

[lscrd]

Yes, this is rather strange. I was able to make it work using an explicit range.
    
    
    type
      R = range[0..63]
      H = set[R]
    
    var h: H = {R(1)}
    
    
    Run

For sure, the compiler expects the values in the set literal to be of the 
"right" type. Apparently, that means here that 1 alone cannot work.