Interesting paper on composing type definitions

[Andrei Alexandrescu via Digitalmars-d]

On 3/4/17 10:36 PM, Andrei Alexandrescu wrote:
> https://pdfs.semanticscholar.org/5de7/591a853ec947f8de7dc70df0b2ecc38b8774.pdf
> -- Andrei

An idea inspired by this paper would be a type Sum such that Sum!(A, B) 
stores both states of A and B and the joint API offered by the two. 
Would be a good exercise in applying introspection. Also, when there are 
clashing primitives, Sum might offer the option to make one of the types 
"dominant", eliminate the function from the joint interface, or disallow 
composition altogether. -- Andrei