Generic programming by default

[spdegabrielle]

Generic programming by default: map, fold, and friends are generic and not specialized to lists. - @takikawa 3 Oct 2012

[sorawee]

Dup of #19

[jackfirth]

Closing as duplicate of #19.

[rocketnia]

On the Discord, the idea of making + generic has come up a couple of times now. That would fall under this issue, but probably not #19 since not all values that support + are necessarily "collections." Should this be reopened?

[jackfirth]

Maybe "operator overloading" would be a better description of that behavior?

[rocketnia]

That would be too narrow. Operator overloading is an approach to +, but I think a lot of extensions to + will really be attempts to extend the whole numeric tower, and I think extensions to the numeric tower will tend to revolve around defining where a new number type fits into the existing lattice of implicit coercions. I think the term "operator overloading" isn't broad enough to describe that kind of technique, while the term "generic programming" reflects the goal to allow different call sites to call + with different types, no matter what technique ends up being used to achieve that goal.