chrilves

/* Modified version of https://gist.github.com/non/51b83d0abc929cc4f0b153accf2bf02f
 * to expose it's GADT's nature and provide the folding function.
 *
 * Should run out of the box with: amm <the_file>
 */

import $ivy.`org.typelevel:cats-core_2.12:1.6.0`
object demo {

import cats.{Applicative, Functor, Id, Semigroupal, Traverse}

non

package demo

import cats.{Applicative, Functor, Id, Semigroupal, Traverse}
import cats.arrow.FunctionK

/**
 * Type-lifting operation to replace the wildcard type (i.e. _).
 *
 * In some cases we end up with code like: List[Option[_]]. This is
 * fine unless you later need to write code in terms of a particular

ursuad

Kafka Topics

List existing topics

bin/kafka-topics.sh --zookeeper localhost:2181 --list

Describe a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --describe --topic mytopic

Purge a topic

bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic mytopic --config retention.ms=1000

... wait a minute ...

rauchg

require-from-twitter

Since Twitter doesn't have an edit button, it's a suitable host for JavaScript modules.

How to use

Source tweet: https://twitter.com/rauchg/status/712799807073419264

const leftPad = await requireFromTwitter('712799807073419264');

cb372

Category theory jargon cheat sheet

A primer/refresher on the category theory concepts that most commonly crop up in conversations about Scala or FP. (Because it's embarassing when I forget this stuff!)

I'll be assuming Scalaz imports in code samples, and some of the code may be pseudo-Scala.

Functor

A functor is something that supports map.