Gen - a generics library for Go

http://clipperhouse.github.io/gen/

by hebz0rl • 13 years ago

104 48 13 years ago

clipperhouse.github.io

shurcooL• 13 years ago

Here is someone trying to come up with a good solution for generics, rather than simply complaining it don't exist. I am thankful for the effort.

stefantalpalaru• 13 years ago

Good? It's an ugly hack with limited functionality (due to Go's design, not the developers' skill and good will). A good solution would be forking the reference compiler and doing a proper implementation.

KevinEldon• 13 years ago

The library is Go. What you're suggesting seems to be extending Go so that it becomes some other language derived from Go. Extending Go might make for a cleaner and/or better generics solution but if you have to have customized compiler to run the code then you're no longer running Go.

allochthon• 13 years ago

I'm interested in Go but haven't looked into it yet. The fact that we're even talking about "generics" makes me nervous about further exploring it. Generic collections that have clean, dry implementations seem to be pretty much a requirement for new programming languages, in the way that core support for hashes is.

kazagistar• 13 years ago

I think if he gets something good enough that Go devs like, then some form of it might very well be rolled into the compiler itself.

pjmlp• 13 years ago

Some of us use languages with parametric types since the mid-90's.

coldtea• 13 years ago

Here is someone trying to come up with a good solution for generics, rather than simply complaining it don't exist.

That's a hack. Complaining that they don't exist might eventually result in a better language.

namelezz• 13 years ago

Just because there is no solutions yet, it does not mean you can just throw out any solution. I don't think code generation is a good solution for generics but I like the Linq feature though.

c-a2• 13 years ago

Why call it a library when it's a code generator/compiler?

Refefer• 13 years ago

I would argue this is a new language which just happens to compile to go.

c-a2• 13 years ago

Actually it's a code generator with a library of functions it can generate. This is how the "generics" are implemented: https://github.com/clipperhouse/gen/blob/master/templates.go

mwsherman3• 13 years ago

Author here, you’re right. I prefer to call it a tool or an ‘approach’ but whatevs. :)

LukeShu• 13 years ago

This looks similar to an older generics system for Go, `got` (GO Templates). Got was pretty cool, but Go 1.0 broke it due to the parser getting stricter.

Edit: found it: https://github.com/droundy/gotgo

mseepgood3• 13 years ago

These higher-order functions are a very inefficient way to write loops in Go. When you chain them you will end up with multiple sequential iterations instead of only one. Sort should not allocate and return a new slice, it's better to sort in-place, etc.

rybosome3• 13 years ago

That's functional programming for you. It's definitely less efficient, but there are other major advantages. For one thing, given the propagation of immutable data, things can be parallelized effortlessly - look at 'pmap' in Clojure for example. Once you're familiar with the style, it's significantly more concise and readable.

That being said, a systems programming language may not be the right place for FP concepts.

saryant2• 13 years ago

Scala gets around this with "views": store the higher-order functions until the collection actually needs to be used and then apply them all at once, without any intermediate data structure.

http://docs.scala-lang.org/overviews/collections/views.html

coolsunglasses2• 13 years ago

That's functional programming for you.

Uhm, what? No it's not.

Haskell has stream fusion, thereby generating assembler that looks a lot like the optimal imperative version.

Dewie• 13 years ago

That being said, a systems programming language may not be the right place for FP concepts.

It's good enough for Rust.

krakensden• 13 years ago

things can be parallelized effortlessly

If you're not using a language with Clojure's nifty datastructures, "effortlessly" probably isn't much better than OpenMP.

atilaneves• 13 years ago

D is a systems programming language with FP concepts and they work quite well. Also, it has generics / templates / parametric polymorphism that are more powerful and easier to use than C++.

mwsherman3• 13 years ago

It’s by design, though I understand the concern. From a design perspective, I like getting a distinct slice out the other end, without having to wonder whether I’ve mutated my original slice. It’s more stateless, so to speak.

Fwiw, slices are inexpensive by design. The elements themselves are not copied. Allocating a new slice is really a small ‘struct’ which serves as a pointer to the underlying array: http://blog.golang.org/go-slices-usage-and-internals

(Gen’ing pointers is supported, which mitigates the potential for allocation.)

It is true that chained operations will be multiple iterations. Whether it will net out to more iterations than otherwise depends on the use.

I’d be interested to see if someone can come up with a pattern where the operations themselves are composed, with a ’.Results()’ method that can intelligently (lazily?) minimize iterations. That’d be impressive.

Xelom• 13 years ago

Thanks for your effort. This is not about the library. Your site's mobile version is kinda broken. The left menu thingy always remain in the site and you can't read the main context. This happened to me on my Android Firefox Browser.

StavrosK• 13 years ago

Same here, I couldn't read it at all.

mwsherman3• 13 years ago

Author here, pleasantly surprised to see this on HN.

There is a substantial set of changes happening out on this branch: https://github.com/clipperhouse/gen/tree/projection.

… for this reason: https://github.com/clipperhouse/gen/issues/8

stiff5• 13 years ago

I really hope this will get solved in the language itself, I like Go quite a bit, but there are quite ugly places, all related to generics I guess:

- No min/max for integers (and Go doesn't have the ternary operator)

- No IsMember for checking if an object is in a collection

- Directly from the Gen page: Go’s sort package requires the fulfillment of three interface members, two of which are usually boilerplate. If you want to sort by different criteria, you need to implement multiple ‘alias’ types.

Also, unrelated to generics, but no multidimensional arrays.

mseepgood3• 13 years ago

no multidimensional arrays

That's not true, e.g. [4][4]byte is a multi-dimensional array. It's a contiguous block of 16 bytes of memory.

stiff5• 13 years ago

The size has to be known at compile time, though. One can do a slice of slices, but then it's not necessarily continuous in memory. So you are left with allocating a one dimensional array of size x*y and doing index calculations by hand like in the good old 70's or something.

Gen - a generics library for Go

Related Stories