Add NonEmptyMap #2141

LukaJCB · 2018-01-08T16:54:43Z

This is basically just a copy-paste from https://github.com/LukaJCB/cats-maps-sets, I still need to add some more scaladoc and maybe a test here or there, but if someone has some early feedback I'd love to hear!

codecov-io · 2018-01-08T19:10:37Z

Codecov Report

Merging #2141 into master will increase coverage by 0.04%.
The diff coverage is 96.29%.

@@            Coverage Diff             @@
##           master    #2141      +/-   ##
==========================================
+ Coverage   94.76%   94.81%   +0.04%     
==========================================
  Files         331      332       +1     
  Lines        5659     5742      +83     
  Branches      208      212       +4     
==========================================
+ Hits         5363     5444      +81     
- Misses        296      298       +2

Impacted Files	Coverage Δ
core/src/main/scala/cats/data/package.scala	`87.5% <ø> (ø)`	⬆️
core/src/main/scala/cats/data/NonEmptyList.scala	`100% <100%> (ø)`	⬆️
...rc/main/scala/cats/laws/discipline/Arbitrary.scala	`100% <100%> (ø)`	⬆️
...ore/src/main/scala/cats/data/NonEmptyMapImpl.scala	`95.94% <95.94%> (ø)`
core/src/main/scala/cats/data/Kleisli.scala	`97.93% <0%> (+0.04%)`	⬆️
core/src/main/scala/cats/instances/sortedMap.scala	`96.87% <0%> (+1.56%)`	⬆️

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jtjeferreira · 2018-01-12T13:55:19Z

should cats.data.NonEmptyList#groupBy return an NonEmptyMap?

LukaJCB · 2018-01-12T14:07:29Z

@jtjeferreira that's an excellent idea in my opinion, however it might not be feasible to change it though due to backwards compatibility.

jtjeferreira · 2018-01-12T14:39:25Z

maybe add a new method groupByNem

jozic · 2018-01-13T00:49:55Z

core/src/main/scala/cats/data/NonEmptyMap.scala

+
+import scala.collection.immutable._
+
+final class NonEmptyMap[K, A] private(val value: SortedMap[K, A]) extends AnyVal {


does it have to be a SortedMap?

What would you want it to be?

just immutable.Map[K,A]?
or maybe a better name for the class then NonEmptySortedMap?

kailuowang · 2018-01-25T12:09:15Z

I will find some time Friday.

LukaJCB · 2018-01-25T12:14:14Z

Excellent, thank you @kailuowang! No rush at all :)

ceedubs · 2018-01-25T15:11:00Z

@LukaJCB @kailuowang sorry, I'm unlikely to find time for any reviews until Feb 4th or so.

LukaJCB · 2018-01-25T15:13:11Z

No worries at all @ceedubs! No need to rush :)

LukaJCB · 2018-01-26T14:18:01Z

core/src/main/scala/cats/data/NonEmptyMap.scala

+    * res0: scala.collection.immutable.SortedSet[Int] = Set(1, 2)
+    * }}}
+    */
+  def keys: SortedSet[K] = value.keySet


This should be a non empty set

kailuowang · 2018-01-26T16:09:19Z

core/src/main/scala/cats/data/NonEmptyMap.scala

@@ -0,0 +1,343 @@
+/*
+ * Copyright (c) 2018 Luka Jacobowitz


Shall we add a copyright header to all files in a separate PR (I am thinking maybe we can use sbt-header)

Sounds like a good idea!

Shall we use copyright maintainers like the website or each file copyright goes to individual creators?

Copyright maintainers seems best to me, I just copy and pasted this one from my own project 😄

kailuowang

LGTM

LukaJCB · 2018-01-31T23:43:47Z

core/src/main/scala/cats/data/NonEmptyMap.scala

-  /**
-    * Adds a key-value pair to this map, returning a new `NonEmptyMap`.
-    * */
-  def +(ka: (K, A)): NonEmptyMap[K, A] = new NonEmptyMap(value + ka)


I had to get rid of this operator because of the super annoying any2StringAdd :(

kailuowang · 2018-02-01T17:58:50Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

@@ -317,7 +322,7 @@ private[data] sealed abstract class NonEmptyMapInstances {
  implicit def catsDataShowForNonEmptyMap[K: Show, A: Show]: Show[NonEmptyMap[K, A]] =
    Show.show[NonEmptyMap[K, A]](_.show)

-  implicit def catsDataBandForNonEmptyMap[K, A]: Band[NonEmptyMap[K, A]] = new Band[NonEmptyMap[K, A]] {
+  implicit def catsDataSemilatticeForNonEmptyMap[K, A]: Semilattice[NonEmptyMap[K, A]] = new Semilattice[NonEmptyMap[K, A]] {


you changed it to semilattice here but not the law testing? I am not sure if Map combine is commutative.

Oh, right, yeah that was dumb, I'll check that one later :)

aeons · 2018-02-05T12:10:14Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+  implicit def catsNonEmptyMapOps[K, A](value: Type[K, A]): NonEmptyMapOps[K, A] =
+    new NonEmptyMapOps(value)
+
+


Nitpicky, I know, but there are a lot of these double empty lines around.

kailuowang

noice.

durban

I've left some comments.

durban · 2018-02-06T08:26:07Z

core/src/main/scala/cats/data/package.scala

@@ -11,6 +11,9 @@ package object data {
  def NonEmptyStream[A](head: A, tail: A*): NonEmptyStream[A] =
    OneAnd(head, tail.toStream)

+  type NonEmptyMap[K, +A] = NonEmptyMapImpl.Type[K, A]
+  val NonEmptyMap = NonEmptyMapImpl


What's the inferred type here? I'd guess NonEmptyMapImpl.type, but that cannot be, since it's private[data] ...

It is its own type aka, cats.data.NonEmptyMap.type :)

Well, sure ... but that's not what I asked. The inferred type seems to be this:

private[this] val NonEmptyMap: cats.data.NonEmptyMapImpl.type = NonEmptyMapImpl; <stable> <accessor> def NonEmptyMap: cats.data.NonEmptyMapImpl.type = `package`.this.NonEmptyMap;

Which means that we have a private[data] type on a public API.

durban · 2018-02-06T08:31:07Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+  def one[K: Order, A](k: K, a: A): NonEmptyMap[K, A] =
+    create(SortedMap((k, a))(Order[K].toOrdering))
+
+  implicit def catsNonEmptyMapOps[K, A](value: Type[K, A]): NonEmptyMapOps[K, A] =


This is supposedly a public method, but its return type is private[data].

durban · 2018-02-06T08:33:41Z

core/src/main/scala/cats/data/package.scala

@@ -11,6 +11,9 @@ package object data {
  def NonEmptyStream[A](head: A, tail: A*): NonEmptyStream[A] =
    OneAnd(head, tail.toStream)

+  type NonEmptyMap[K, +A] = NonEmptyMapImpl.Type[K, A]


Should this be called NonEmptySortedMap? There might be in the future a hashtable-based non-empty map ...

durban · 2018-02-06T08:35:41Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+
+}
+
+private[data] sealed class NonEmptyMapOps[K, A](val value: NonEmptyMapImpl.Type[K, A]) {


Maybe private val value?

durban · 2018-02-06T08:37:33Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+  /**
+    * Returns a `SortedSet` containing all the keys of this map.
+    */
+  def keys: SortedSet[K] = toSortedMap.keySet


Could this be NonEmpty(Sorted)Set?

Yep, as mentioned before here :) #2141 (comment)

2141 merged :)

durban · 2018-02-06T08:37:50Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+    */
+  def head: (K, A) = toSortedMap.head
+  /**
+    * Returns the first key-value pair of this map.


first -> last

durban · 2018-02-06T08:40:33Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+
+
+  /**
+    * Apply `f` to the "initial element" of this map and lazily combine it


What does lazily mean in this case?

A mistake 😄

ceedubs · 2018-02-11T19:33:59Z

core/src/main/scala/cats/data/Newtype2.scala

+package cats
+package data
+
+trait Newtype2 { self =>


This seems kind of strange. Is this the same as the Newtype in the Set PR?

This one has two type parameters.

durban · 2018-02-12T14:26:37Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+
+}
+
+sealed class NonEmptyMapOps[K, A](val value: NonEmptyMap[K, A]) {


Maybe private val value?

These are just the Ops, what do we gain from making the value public? :)

Nothing, that's why I suggested making it private :-)
In fact, I think it shouldn't be a val at all.

Oh yeah, I got it switched around in my head 😄
Currently all of our Ops Syntax classes look this way and consistency is good the way I see it.
What would it be if not a val?

Adding val makes it a member on the class, omitting it, it's only in the constructor.

Huh, yeah that makes sense, I wonder why that's the convention for syntax classes in cats, maybe someone else can chime in 🤔

@LukaJCB you have to make it public (ie val) if it's a value class, which is why you see it on other syntax classes.

If I remember correctly the reason it must be public is 2.10. For 2.11 and 2.12 private would work as well.

ceedubs · 2018-03-09T03:46:12Z

core/src/main/scala/cats/data/NonEmptyMapImpl.scala

+    else throw new IllegalArgumentException("Cannot create NonEmptyMap from empty map")
+
+  def apply[K: Order, A](head: (K, A), tail: SortedMap[K, A]): NonEmptyMap[K, A] =
+    create(SortedMap(head)(Order[K].toOrdering) ++ tail)


This and I think some other methods don't follow the convention that we kind of settled on in the early days of Cats here. Admittedly, that never got added to the guidelines, and I'm not sure whether we have been consistent about that in other places.

I personally don't have a strong opinion on this and didn't know we had such a convention 😄, you're right we should maybe reopen discussion and add it to the guideline, but for now I'll just change it, so we can avoid calling apply on the companion 👍 Thanks!

LukaJCB · 2018-03-16T12:34:47Z

@ceedubs everything addressed? :)

ceedubs

👍 LGTM

stew added the in progress label Jan 8, 2018

LukaJCB mentioned this pull request Jan 8, 2018

Add NonEmptySet #2143

Merged

Add NonEmptyMap

bab788b

LukaJCB force-pushed the add-nonemptymap branch from 9ec1efb to bab788b Compare January 8, 2018 17:20

jozic reviewed Jan 13, 2018

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LukaJCB added enhancement and removed in progress labels Jan 15, 2018

LukaJCB added this to the 1.1 milestone Jan 15, 2018

Add more docs

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LukaJCB force-pushed the add-nonemptymap branch from 7c6ae01 to 31ecdac Compare January 15, 2018 18:28

chuwy mentioned this pull request Jan 19, 2018

Add NonEmptyList.fromListGroupBy #2157

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LukaJCB requested review from kailuowang and ceedubs January 24, 2018 22:37

LukaJCB commented Jan 26, 2018

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LukaJCB requested a review from johnynek January 26, 2018 14:30

kailuowang reviewed Jan 26, 2018

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kailuowang previously approved these changes Jan 29, 2018

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Move to newtype encoding

8a2b024

LukaJCB dismissed kailuowang’s stale review via 8a2b024 January 31, 2018 23:42

LukaJCB commented Jan 31, 2018

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Luka Jacobowitz added 2 commits February 1, 2018 00:47

Rename NonEmptyMap#get to not conflict with Reducible.get

aa4ca5e

Fix 2.11 and 2.10 compilation

7525ca8

Fix 2.10 as well

f116d96

LukaJCB force-pushed the add-nonemptymap branch from 9db1fbb to f116d96 Compare February 1, 2018 12:23

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Luka Jacobowitz added 3 commits February 2, 2018 10:59

Remove semilattice instance

387dec1

Extra tests

5811a50

Add groupByNem to NonEmptyList

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LukaJCB force-pushed the add-nonemptymap branch from 7afc89f to 57e907c Compare February 5, 2018 09:18

Hide more newtype machinery

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LukaJCB dismissed kailuowang’s stale review via a16d9e1 February 7, 2018 12:05

Move newtype to its own file

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ceedubs reviewed Feb 11, 2018

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Address feedback

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ceedubs reviewed Mar 9, 2018

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Luka Jacobowitz added 4 commits March 11, 2018 16:10

Remove context bounds

0e07055

Make newtype private

22c471c

Merge branch 'master' into add-nonemptymap

e63f01f

keys now returns a NonEmptySet

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kailuowang approved these changes Mar 14, 2018

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kailuowang merged commit 55e0902 into typelevel:master Mar 16, 2018

LukaJCB deleted the add-nonemptymap branch March 16, 2018 14:31


		import scala.collection.immutable._

		final class NonEmptyMap[K, A] private(val value: SortedMap[K, A]) extends AnyVal {

		implicit def catsNonEmptyMapOps[K, A](value: Type[K, A]): NonEmptyMapOps[K, A] =
		new NonEmptyMapOps(value)


		}

		private[data] sealed class NonEmptyMapOps[K, A](val value: NonEmptyMapImpl.Type[K, A]) {



		/**
		* Apply `f` to the "initial element" of this map and lazily combine it


		}

		sealed class NonEmptyMapOps[K, A](val value: NonEmptyMap[K, A]) {

Add NonEmptyMap #2141

Add NonEmptyMap #2141

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LukaJCB commented Jan 8, 2018

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