non/spire

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Luka Jacobowitz

@LukaJCB

I thought it was always commutative in its addition :o

Oh I realized I had an error in my code above, what I meant was this:

trait Semiring[A] extends CommutativeMonoid[A] {
  def times[A](x: A, y: A): A

  def plus[A](x: A, y: A): A = combine(x, y)
  def zero[A] = empty[A]
}

trait Rig[A] extends Semiring[A] {
  def one[A]: A
}

Luka Jacobowitz

@LukaJCB

Would it be very wrong to add a cats.kernel.Monoid[Rational] that’s consistent with the Monoids for Int, Long,BigInt, etc.?

Denis Rosset

@denisrosset

My bad, indeed it is commutative in addition!

Spire does not extend the cats instances yet, and we haven't taken a position on whether our instances/laws/... should be inherited through the chain cats-kernel/algebra/spire

You're very welcome to add an optional Monoid[Rational] in spire.optional; however, I'm not clear about the default instances in spire, and reluctant to pile more stuff on top of it

Spire is currently in "clean up" mode as it accumulated a lot of things, and we lack the bandwidth to do that clean up

(we are currently at ~ 50% code coverage, which is a shame)

Luka Jacobowitz

@LukaJCB

Yeah it’s a pretty big project, but it has a lot of awesome stuff

Denis Rosset

@denisrosset

Thanks! Actually, can you open a spire issue with the problem of the default Monoids? We will likely not make a lot of progress in the next weeks, but it's something we have to address during the cleanup

Luka Jacobowitz

@LukaJCB

I can try to help out where I can as well :)

Denis Rosset

@denisrosset

Thanks a lot!

Luka Jacobowitz

@LukaJCB

I really love Algebra and Spire and they deserve more attention than they get :D

Denis Rosset

@denisrosset

@peterewills How is it going? Need help digging through Spire's code?

Me too! Love that we actually have a better type tower than Haskell in some places (TruncatedDivision notably!)

Luka Jacobowitz

@LukaJCB

Indeed!

Should I open the issue in Typelevel/algebra? Technically Semiring is defined there

Denis Rosset

@denisrosset

Would say both.

Another underlying theme is whether we should share default instances as well.

Luka Jacobowitz

@LukaJCB

What do you mean by “share”? :)

Luka Jacobowitz

@LukaJCB

non/spire#740 and typelevel/algebra#218

Srepfler Srdan

@schrepfler

is a Rational(1, 0) valid?

Luka Jacobowitz

@LukaJCB

If we end up merging algebra into cats it would be great to have you on the team @denisrosset :)

Denis Rosset

@denisrosset

@schrepfler No it's not. Should throw an Exception during construction.

Colt Frederickson

@coltfred

Where are the notes for 0.15 and 0.16? Latest I see here is 0.14.1 https://github.com/non/spire/blob/master/CHANGES.md

Also, I assume they're not compatible? My tests freak out with cNoSuchMethodError...

Denis Rosset

@denisrosset

@coltfred, we are breaking compatibility all the time, and indeed, the latest releases do not have accompanying notes.

The biggest pain with Spire now is that some parts are production ready (and simply need more test coverage), while others are shaky.

@LukaJCB That would be cool!

Cory Parent

@goedelsoup

has anyone explored or knows of an exploration in applying spire to geodesics?

Denis Rosset

@denisrosset

@goedelsoup Haven't heard of it, but I would be curious of seeing which algebraic structure underlie geodesics

Cory Parent

@goedelsoup

i'm an expert at neither, but am planning on using spire to work through a text on the topic. my initial uneducated view is that it's a pile of polynomial rings.

i'll definitely report back if i find it worthy of note. most of the existing code in this space is quite nightmarish.

Luciano

@lJoublanc

Excuse my ignorance, but I'm looking to implement a toy crypto system, which requires a finite field under mod N, and wondered whether there was already an instance in spire (or friends)?
Am I also right in that there is no integral Field because integral multiplication inverse isn't well defined? Or something to do with complexity of implementing gcd etc.?

Denis Rosset

@denisrosset

What is an integral field?

Finite fields can be implemented in Spire for sure; fields have trivial euclidean division (as all non zero elements have an inverse), and the GCD is more or less arbitrary.

Denis Rosset

@denisrosset

And indeed, integers do not form a field, rather an Euclidean ring because not all nonzero elements have a multiplicative inverse.

Luciano

@lJoublanc

Thanks Denis. I'm probably not using the correct terminology, sorry.

What is an integral field?

I mean a finite field over the integers modulo N, with it's additive operation being multiplication modulo N, and it's multiplicative operation being exponentiation mod N.

And indeed, integers do not form a field,

Thanks. This makes sense to me now. The set I'm looking at is definitely a field.

Denis Rosset

@denisrosset

Finite fields are fields, so you are fine!

JerrySwan

@JerrySwan

Hi all. Is there a simple way to implement a function:
def restrict(restrictMe: Interval[Double], restrictTo: Interval[Double]): Interval[Double]
such that:
restrict(restrictMe,restrictTo).isSubsetOf(restrictTo)?

Denis Rosset

@denisrosset

On my phone, but there should be a method for interval intersection.

Denis Rosset

@denisrosset

@JerrySwan it is interval1.intersect(interval2)

Grigory

@pomadchin

hey guys, are there any plans to bump up deps in spire?

we depend on cats 1.4 and what to depend on latest spire

but it looks like https://mvnrepository.com/artifact/org.typelevel/algebra_2.12/1.0.0 depends on old cats version

Denis Rosset

@denisrosset

Cats 1.0 is binary compatible across releases, so I haven't had any problems mixing versions.

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