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@retronym
retronym / type-bounds.scala
Created December 16, 2009 11:17
Tour of Scala Type Bounds
class A
class A2 extends A
class B
trait M[X]
//
// Upper Type Bound
//
def upperTypeBound[AA <: A](x: AA): A = x
@oxbowlakes
oxbowlakes / 3nightclubs.scala
Created May 13, 2011 15:14
A Tale of 3 Nightclubs
/**
* Part Zero : 10:15 Saturday Night
*
* (In which we will see how to let the type system help you handle failure)...
*
* First let's define a domain. (All the following requires scala 2.9.x and scalaz 6.0)
*/
import scalaz._
import Scalaz._
@tonymorris
tonymorris / SKI_Applicative.scala
Created August 2, 2012 04:59
Applicative Functor / SKI combinator calculus
object SKI_Applicative {
/*
First, let's talk about the SK combinator calculus and how it contributes to solving your problem.
The SK combinator calculus is made of two functions (aka combinators): S and K. It is sometimes called the SKI combinator calculus, however, the I combinator can be derived from S and K. The key observation of SK is that it is a turing-complete system and therefore, anything that can be expressed as SK is also turing-complete. Here is a demonstration that Scala's type system is turing-complete (and therefore, undecidable) for example[1].
The K combinator is the most trivial of the two. It is sometimes called "const" (as in Haskell). There is also some discussion about its evaluation strategy in Scala and how to best express it[2]. The K function might be paraphrased as, "takes a value and returns a (constant) unary function that always returns that value."
*/
def k[A, B]: A => B => A =
a => _ => a
@travisbrown
travisbrown / tuple-flatten.scala
Created October 24, 2012 11:18
Flattening deeply nested tuples with Shapeless
import shapeless._
trait Flatten[I, O <: HList] {
def apply(i: I): O
}
trait FlattenLow {
implicit def otherFlatten[I] = new Flatten[I, I :: HNil] {
def apply(i: I) = i :: HNil
}
@poetix
poetix / RecorderSpec.scala
Created January 14, 2013 17:20
A monad which captures dynamic method invocations against multiple targets (for use in implementing object builders / matchers)
package com.youdevise.lofty
import org.specs2.mutable._
import scala.language.dynamics
trait State[S, A] {
val runState: Function[S, (S, A)]
def flatMap[B](f: A => Function[S, (S, B)]):Function[S, (S, B)] = (state:S) => {
val (newState, value) = runState(state)
f(value)(newState)
@poetix
poetix / builder.scala
Created January 15, 2013 12:26
Dynamic / Monadic object builder round 2
package com.youdevise.lofty
import org.specs2.mutable._
import scala.language.dynamics
import scala.language.reflectiveCalls
import scalaz._
import Scalaz._
import scala.reflect.runtime.universe._
trait Builder[T] {
@Mortimerp9
Mortimerp9 / readerwithtooling.scala
Created April 14, 2013 22:14
An implementation of the Reader Monad in scala, with correct type variance and some implicit utils to simplify the daily use of Readers, In particular with Future.
/**
* A monad to abstract dependencies in the code, see https://coderwall.com/p/kh_z5g
*/
object Reader {
/**
* an implicit to convert a function A => B in a Reader[A, B]
*/
implicit def reader[C, R](block: C => R): Reader[C, R] = Reader(block)
@debasishg
debasishg / gist:8172796
Last active April 20, 2025 12:45
A collection of links for streaming algorithms and data structures

General Background and Overview

  1. Probabilistic Data Structures for Web Analytics and Data Mining : A great overview of the space of probabilistic data structures and how they are used in approximation algorithm implementation.
  2. Models and Issues in Data Stream Systems
  3. Philippe Flajolet’s contribution to streaming algorithms : A presentation by Jérémie Lumbroso that visits some of the hostorical perspectives and how it all began with Flajolet
  4. Approximate Frequency Counts over Data Streams by Gurmeet Singh Manku & Rajeev Motwani : One of the early papers on the subject.
  5. [Methods for Finding Frequent Items in Data Streams](http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.187.9800&amp;rep=rep1&amp;t
@runarorama
runarorama / gist:a8fab38e473fafa0921d
Last active April 13, 2021 22:28
Compositional application architecture with reasonably priced monads
sealed trait Interact[A]
case class Ask(prompt: String)
extends Interact[String]
case class Tell(msg: String)
extends Interact[Unit]
trait Monad[M[_]] {
def pure[A](a: A): M[A]
@kevinwright
kevinwright / scaladays2014.md
Last active November 16, 2024 17:40
Scaladays 2014 slides

As compiled by Kevin Wright a.k.a @thecoda

(executive producer of the movie, and I didn't even know it... clever huh?)

please, please, please - If you know of any slides/code/whatever not on here, then ping me on twitter or comment this Gist!

This gist will be updated as and when I find new information. So it's probably best not to fork it, or you'll miss the updates!

Monday June 16th