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Comment by azth | Hacker News Reader

> We implemented an optimized (for in polygon search) R-tree data structure for the lookups.

I wouldn't be surprised that due to the lack of generics in golang, this approach was less feasible.

Where would they even use generics? All their algorithm requires is arrays of polygons, and a function to check if a polygon contains a point.

To store the RTree entries. Say you want to switch between 32 bit and 64 bit floating point types in your implementation, without re-writing the entire thing.

sed -i s/float/double/ *.go

What do you actually need generics for that you can't do with interfaces? Not to mention that compile-time generics (read: generating code for each type) make testing with mock types much, much harder.

Type safety and performance.

Also, how does it make testing harder?

Not everything could be type safe with generics.

You can't typecheck the generic itself. Especially conversions could be really hard with them.

(I love generics, still this somewhat aweful). Currently Converting Generics between Scala and Java is totally Ugly.

Could you provide an example? I'd be interested to know more.

Not another dismissive comment about the lack of generics in Go again.

I don't know that it's dismissive so much a factual statement.

OMG, seriously? Because people couldn't implement smart data structures before generics were invented?

(disclaimer: i think that lack of generics in Go is a mistake)

We could, but we got clever adopted the ideas of CLU, Ada, Eiffel and ML and stop doing that in the early 2000's.

Go generate, for example, brings me back memories of a time C++ compilers used pre-processor magic for generic programming, around 1994 or so.

Something like

    #define Type1 my nice type1 definition
    #include <generic-list.h>

    #undef  Type1
    #define Type1 my nice type2 definition
    #include <generic-list.h>

    ListType1 ...
    ListType2 ...

This one uses a "Spatial" interface and has worked well enough with a little bit of tuning.

https://github.com/dhconnelly/rtreego

Using an interface is not good for performance.

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