jonifreeman

Bus of Doom

In a previous Bacon blog post a way to structure Bacon application was outlined. It introduces Buses as a central way to glue components with each other. I'm in a very strong disagreement with the proposed style. Why?

Quoting Erik Meijer

Subjects are the "mutable variables" of the Rx world and in most cases you do not need them.

In Bacon parlance that would be

jonifreeman

  case class Book(title: String, date: Date, author: String)
  val someDate = new Date

  /* Would be nice to return String, PreparedStmt or something instead of Dynamic
  val books: Dynamic[String] = Book
  val q1 = books.findByTitle("The Stand")        // q1, q2 and q3 are Strings
  val q2 = books.findByTitleLike("Harry Pot%")
  val q3 = books.findByDateGreaterThan(someDate)
  */

jonifreeman

  case class Book(title: String, date: Date, author: String)
  val someDate = new Date

  /* Would be nice to return String, PreparedStmt or something instead of Dynamic
  val books: Dynamic[String] = Book
  val q1 = books.findByTitle("The Stand")     
  val q2 = books.findByTitleLike("Harry Pot%")
  val q3 = books.findByDateGreaterThan(someDate)
  */

jonifreeman

implicit def elvisSyntax[A](o: Option[A]) = new { 
  def ?[B](f: A => Option[B]) = o flatMap f 
  def :?[B](f: A => B) = o map f
  def ??(default: => A) = o getOrElse default 
}

case class Head(name: String) 
case class Department(head: Option[Head])
case class Employee(department: Option[Department])

jonifreeman

("lotto" ->
  ("lotto-id" -> lotto.id) ~
  ("winning-numbers" -> lotto.winningNumbers) ~
  ("winners" ->
    lotto.winners.map { w =>
      (("winner-id" -> w.id) ~
       ("numbers" -> w.numbers))}))

// vs.

jonifreeman

import System.IO
import Control.Exception
import Numeric.LinearAlgebra
import Data.Digest.Pure.SHA
import Data.ByteString.Lazy.Char8 as BS8 (pack)
import Data.List (sort)
import System.Random (randomRIO)
import Network.Curl
import Text.Printf (printf)
import Data.List.Split (splitOn)

jonifreeman

-- LinExtras.hs, some hmtarx helpers

module LinExtras where

import Numeric.LinearAlgebra
import Foreign.Storable (Storable)

vector xs = fromList xs :: Vector Double

-- Each entry is a column.

jonifreeman

-- LinExtras.hs, some hmtarx helpers

module LinExtras where

import Numeric.LinearAlgebra
import Foreign.Storable (Storable)

vector xs = fromList xs :: Vector Double

-- Each entry is a column.

jonifreeman

-- LinExtras.hs

module LinExtras where

import Numeric.LinearAlgebra
import Foreign.Storable (Storable)

vector xs = fromList xs :: Vector Double

size :: (Num b) => Vector Double -> b

jonifreeman

data State_t a s = State a s

let unit = {}

let stateMonad = {
  return: \x -> \s -> State x s

  bind: \sm f -> \s0 -> match (sm s0)
    case (State x s) = (f x) s
}