L7R7

countOccurrences :: (Ord k, Num a) => (t -> k) -> [t] -> Map k a
countOccurrences f xs = Map.fromListWith (+) [(f x, 1) | x <- xs]

L7R7

groupWith :: (Ord b) => (a -> b) -> [a] -> Map b [a]
groupWith f xs = Map.fromListWith (++) [(f x, [x]) | x <- xs]

L7R7

partition :: [a] -> (a -> Bool) -> ([a], [a])
partition as f = (filter f as, filter (not . f) as)

partition2 :: [a] -> (a -> Bool) -> ([a], [a])
partition2 as f = foldr combine ([], []) as
  where
    combine elem (ts, fs) =
      if f elem
        then (elem : ts, fs)
        else (ts, elem : fs)

L7R7

import cats.data.Validated

class InvalidNameException extends Exception
class InvalidEmailException extends Exception
class InvalidAgeException extends Exception

object Validations {
  def validateName(name: String): Validated[InvalidNameException, String] =
    if (name.isEmpty) Validated.Invalid(new InvalidNameException())
    else Validated.Valid(name)

L7R7

import io.vavr.collection.Seq;
import io.vavr.control.Validation;

class Demo {
  public static void main(String[] args) {
    String name = "name";
    String email = "ex@mple.com";
    int age = 20;

    Validation<Seq<Exception>, User> user = Validation.combine(

L7R7

import io.vavr.collection.Seq;
import io.vavr.control.Validation;

class Demo {
  public static void main(String[] args) {
    String name = "name";
    String email = "foo@bar.com";
    int age = 20;

    Validation<Seq<UserError>, User> user = Validation.combine(

L7R7

import io.vavr.collection.Seq;
import io.vavr.control.Validation;

class Demo {
  public static void main(String[] args) {
    String name = "name";
    String email = "ex@mple.com";
    int age = 20;

    Validation<Seq<Exception>, User> user = Validation.combine(

L7R7

package com.l7r7.lab.feed.client

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model._
import akka.http.scaladsl.model.headers.Link
import akka.http.scaladsl.unmarshalling.Unmarshal
import akka.stream.scaladsl.Source
import akka.stream.{ ActorMaterializer, Materializer }

L7R7

package com.l7r7.lab.feed.client

import akka.actor.ActorSystem
import akka.http.scaladsl.Http
import akka.http.scaladsl.model.Multipart.General
import akka.http.scaladsl.model._
import akka.http.scaladsl.model.headers.Link
import akka.http.scaladsl.unmarshalling.Unmarshal
import akka.stream.ActorMaterializer
import akka.stream.scaladsl.{ Flow, Source }