Create StateT type #25

arturogutierrez · 2017-03-24T21:49:57Z

Fixes #14

Super basic example of State Monad:

// State for a random 6-dice roll
val dice = State<Random, Int> { r -> Pair(r, r.nextInt(6) + 1) }
// Applying a +3 modifier to the roll
val modDice = dice.map { n -> (n + 3).coerceAtMost(6) } // return a new State<Random, Int> generating only 4-5-6 possible dice values
// Roll example
val d1 = modDice.runA(Random())

raulraja

Excellent, let's replace eval with run. And let's provide runA, runS and run to get just A, just the State or both accordingly

JMPergar

Apply the changes requested by @raulraja and you will have my approved too

codecov · 2017-03-31T07:36:33Z

Codecov Report

Merging #25 into master will decrease coverage by 1.36%.
The diff coverage is 26.78%.

@@             Coverage Diff              @@
##             master      #25      +/-   ##
============================================
- Coverage     54.82%   53.46%   -1.37%     
- Complexity      177      187      +10     
============================================
  Files            77       80       +3     
  Lines          1098     1154      +56     
  Branches        169      169              
============================================
+ Hits            602      617      +15     
- Misses          433      474      +41     
  Partials         63       63

Impacted Files	Coverage Δ	Complexity Δ
katz/src/main/kotlin/katz/instances/StateTMonad.kt	`0% <0%> (ø)`	`0 <0> (?)`
katz/src/main/kotlin/katz/data/State.kt	`100% <100%> (ø)`	`2 <2> (?)`
katz/src/main/kotlin/katz/data/StateT.kt	`32.5% <32.5%> (ø)`	`8 <8> (?)`

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arturogutierrez · 2017-03-31T07:39:55Z

PR updated! :)

ffgiraldez

Update State class to HKT and use Tupled class instead of Pair

ffgiraldez · 2017-03-31T08:59:39Z

katz/src/main/kotlin/katz/data/State.kt

+ * to returning the result of type A, the function
+ * returns a new S value, which is the updated state.
+ */
+class State<S, out A>(val runF: (S) -> Pair<S, A>) {


please use Tuple2 instead of Pair

make it implement HK2<State.F,S,A>

AFAIK, StateT is who has to support HKT, right? This State is using Identity as Monad Environment, isn't?

About Tuple2, I will change it :)

Raul's comment was very clear 😄
I will try to implement StateT 💪

raulraja · 2017-03-31T09:12:25Z

Now that we have Id instead of State this type should be StateT. StateT has three type args.
F, S and A where F is some other monad. once StateT is implemented you can derive State by
type State[S, A] = StateT[Id, S, A].
StateT allows us to use state in other context beside a plain environment such as Id for example Future.

JorgeCastilloPrz · 2017-03-31T15:34:11Z

katz/src/main/kotlin/katz/data/State.kt

+    fun runS(s: S): S = run(s).a
+
+    fun <B> map(f: (A) -> B): State<S, B> {
+        return State { s1 ->


you can remove this return by using fun <B> map(f: (A) -> B) = State<S, B> { ... } syntax

raulraja · 2017-04-02T14:55:00Z

@arturogutierrez take a look at how Reader integrates with Kleisli now in master, you are gonna have to do something similar for StateT and State.

ffgiraldez · 2017-06-06T10:02:42Z

I will gonna update this PR soon

pakoito

Can you please add the Monad instances? It should be just evaluating the parameter and calling the methods in the object.

pakoito

LGTM for shipping. I have never had to overwrite map2 and map2Eval, is there a reason for this? It'd be great to have tests for them.

ffgiraldez · 2017-06-13T07:51:56Z

i see that map2 and map2Eval was defined here in cats

Now that @raulraja are pushing laws i will not do more test on typeclasses and focus on help him to finish it.

Try.onEach

* 0.11.0/bio (#1975) * BIO - Part 1 (#1851) * Add E param * Fix imports & types * Add RaiseError case * Refactor IO name * [BIO]: include `E` into IOFrame & IORunLoop (#1859) * Rewrite IOFrame * Update IORunLoop & fix resulting combinators * Move public code to IO.kt * Refactor Right to Success * IO: IOConnection & IOBracket (#1870) * Update ForwardCancelable * Update IOBracket * Remove KindConnection and refactor into IOConnection * IO Concurrency combinators & Green Build (#1892) * BIO - Part 1 (#1851) * Add E param * Fix imports & types * Add RaiseError case * Refactor IO name * [BIO]: include `E` into IOFrame & IORunLoop (#1859) * Rewrite IOFrame * Update IORunLoop & fix resulting combinators * Move public code to IO.kt * Refactor Right to Success * IO: IOConnection & IOBracket (#1870) * Update ForwardCancelable * Update IOBracket * Remove KindConnection and refactor into IOConnection * Rewrite UnsafePromise * Rewrite ParMap2 * Update IOParMap3 * Update IORacePair * Update IORaceTriple * Fix tests * Fix KIO benchmarks * Fix imports Ank * Fix IOExample * Fix unused imports * Fix imports benchmarks * Fix arrow-integrations-retrofit-adapter * Fix FpToTheMax & typeclasses example * KtLintFormat * Fix IOTest * Fix more tests * Fix merge conflicts * KtLintFormat * Fix MaybeK bracket and use it for QueueTest * Throw proper exception in impossible cases * Revert removing runAsync * Fix build * KtLintFormat * Update version * After releasing 0.10.5: just considering one wip version (#26) Co-authored-by: Simon Vergauwen <[email protected]> Co-authored-by: Simon Vergauwen <[email protected]> Co-authored-by: raulraja <[email protected]>

arturogutierrez added the work in progress label Mar 24, 2017

arturogutierrez self-assigned this Mar 25, 2017

JMPergar self-requested a review March 25, 2017 10:57

raulraja requested changes Mar 25, 2017

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JMPergar approved these changes Mar 26, 2017

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arturogutierrez added 3 commits March 31, 2017 09:25

State skeleton

2e83c3f

State.map added

a747e0e

State.flatMap and State.eval added

5859d3b

arturogutierrez force-pushed the create-state-type branch from fc35894 to 5859d3b Compare March 31, 2017 07:25

Adding runA and runS. Tests included.

9fe70b9

arturogutierrez removed the work in progress label Mar 31, 2017

Moving State to katz root package

6461f1a

ffgiraldez requested changes Mar 31, 2017

View reviewed changes

Using Tuple2 instead of Pair

e907356

JorgeCastilloPrz reviewed Mar 31, 2017

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Merge branch 'master' into create-state-type

f4d580c

ffgiraldez changed the title ~~Create State type~~ Create StateT type Apr 23, 2017

pakoito and others added 2 commits May 16, 2017 00:20

Merge branch 'master' into create-state-type

382b72e

Merge branch 'master' into create-state-type

cd1024d

ffgiraldez assigned ffgiraldez and unassigned arturogutierrez Jun 6, 2017

Implement StateT and replace old State as alias of StateT<Id, S, A>

677ac3f

pakoito requested changes Jun 8, 2017

View reviewed changes

ffgiraldez added the work in progress label Jun 12, 2017

Added StateTMonad

71e013e

Merge branch 'master' into create-state-type

0ed6d53

pakoito approved these changes Jun 12, 2017

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Merge branch 'master' into create-state-type

05b0a93

pakoito merged commit 60ccc36 into master Jun 13, 2017

pakoito deleted the create-state-type branch June 13, 2017 09:26

FPerezP pushed a commit to FPerezP/kategory that referenced this pull request Dec 12, 2017

Merge pull request arrow-kt#25 from nkoder/try_onEach

4fb5aed

Try.onEach

rachelcarmena added a commit that referenced this pull request Feb 24, 2021

Fix dependencies (#25)

affd1cf

rachelcarmena added a commit that referenced this pull request Feb 24, 2021

Doc: fix link for Arrow libraries (#25)

974895e

rachelcarmena added a commit that referenced this pull request Feb 24, 2021

Conf: update actions (#25)

c01852b

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Create StateT type #25

Create StateT type #25

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Create StateT type #25

Create StateT type #25

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