[nicwilson]

Many things, although introspection works glove in hand with generics. Below os a non-exhaustive list.

You can 'Write once - automate everywhere' all the boilerplate. See https://github.com/kaleidicassociates/excel-d/ , for an example of automating the interaction between D and Excel. I am in the process of doing something similar for OpenCL and CUDA and will be presenting it at Dconf.

You can make at compile time (additional) fast paths by checking to see if a type (or symbol or whatever else) provides a fast primitive to accelerate your algorithm. e.g. if Foo implements fastfoo use that otherwise fallback to a general algorithm.

See also Andrei Alexandrescu's 2016(15?) talk (IIRC the relevant section is about half way through https://www.youtube.com/watch?v=4oDK91E3VKs).