hello-cats

core.clj

(ns hello-cats.core
  (:require [cats.core :as m :refer [mlet]]
            [cats.monad.either :as either]
            [cats.monad.maybe :as maybe]
            [cats.monad.identity :as id]
            [cats.context :as ctx]
            [cats.builtin :refer [sum-monoid prod-monoid vector-context]])
  (:gen-class))

(defn m-mappend
  [semigrp-ctx mx my]
  (mlet [x mx
         y my]
    (m/return
     (ctx/with-context semigrp-ctx
       (m/mappend x y)))))

(comment
  (m-mappend sum-monoid (maybe/just 1) (maybe/just 2)) ; => #<Just 3>
  (m-mappend sum-monoid (either/right 1) (either/left "oops")) ; => #<Left "oops">
  (m-mappend sum-monoid [1 2 3 4] [5 6]) ; => [6 7 7 8 8 9 9 10]
  (m-mappend prod-monoid [1 2 3 4] [5 6]) ; => [5 6 10 12 15 18 20 24]
  )

(defn -main
  "I don't do a whole lot ... yet."
  [& args]
  (println "Hello, World!"))