ejconlon

#!/usr/bin/env python

"""
Tail-Recursion helper in Python.

Inspired by the trampoline function at 
http://jasonmbaker.com/tail-recursion-in-python-using-pysistence

Tail-recursive functions return calls to tail-recursive functions
(themselves, most of the time). For example, this is tail-recursive:

ejconlon

#!/usr/bin/env python

"""
Translated from the example in 
Deprecating the Observer Pattern (Maier, Rompf, Odersky)
http://lamp.epfl.ch/~imaier/pub/DeprecatingObserversTR2010.pdf

Their Scala example:
Reactor.once { self =>
	// step 1:

ejconlon

#!/usr/bin/env runhaskell
{-# LANGUAGE MultiParamTypeClasses, FlexibleInstances, TypeSynonymInstances, FunctionalDependencies #-}

{- Monad-like trees can do cool things like factoring integers and 
 - pruning leaves with bind (>>=).
 -
 - Internal nodes are annotated with a measure of some sort that can be used
 - for efficient indexing and sizing. 
 -
 - Measured typeclass and tagged nodes from 

ejconlon

#!/usr/bin/env runhaskell

{- Project Euler 96 - Solve Sudoku!
 -
 - Compile it with ghc -o blah --make sudoku
 -
 - And grab sudoku.txt from 
 - http://projecteuler.net/index.php?section=problems&id=96
 -
 - Answer: 24702

ejconlon

package object tasks {
  trait Task[A, B] {
    private[tasks] def run(): Either[A, B]
    def map[C](f: B => C): Task[A, C] = ???
    def flatMap[C](f: B => Task[A, C]): Task[A, C] = ???
  }
  
  private[tasks] class Http[A, B](
    data: HttpRequest,
    handler: Either[Throwable, HttpResponse] => Either[A, B],

ejconlon

Simple data science operations in Haskell

Simple tasks

1. Read a table of data from disk

Cassava: exploratory CSV parsing

ejconlon

import scala.languageFeature.higherKinds
import cats.{Applicative, Id, ~>}

object Shapes {
  case class Child[F[_]](nickname: F[String], age: F[Int])

  case class Adult[F[_]](job: F[String], innerChild: Child[F])

  class ApplicativeTrans[F[_]](implicit applicativeF: Applicative[F]) extends ~>[Id, F] {
    override def apply[A](value: A): F[A] = applicativeF.pure(value)

ejconlon

package example

import cats.~>
import org.scalatest.FunSuite

object CopSpec {
  final case class Foo[+A](value: A)
  final case class Bar[+A](value: A)
  final case class Baz[+A](value: A)

ejconlon

#!/usr/bin/env stack
-- stack --resolver lts-13.9 --install-ghc runghc --package aeson --package tasty --package text
{-# LANGUAGE DeriveGeneric         #-}
{-# LANGUAGE DerivingVia           #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE OverloadedStrings     #-}
{-# LANGUAGE UndecidableInstances  #-}

import Data.Aeson

ejconlon

#!/usr/bin/env stack
-- stack --resolver lts-13.9 --install-ghc runghc --package aeson --package tasty --package text
{-# LANGUAGE DeriveGeneric         #-}
{-# LANGUAGE DerivingVia           #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE FlexibleContexts      #-}
{-# LANGUAGE OverloadedStrings     #-}
{-# LANGUAGE StandaloneDeriving    #-}
{-# LANGUAGE UndecidableInstances  #-}