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package datalab.pj
import shapeless.ops.hlist.ToTraversable
import shapeless.ops.record._
import shapeless.record._
import shapeless.{HList, LabelledGeneric}
// Recursive versions for Nested Case Classes exist
object CaseClassToMap {
@samgiles
samgiles / flatMap.js
Created June 20, 2014 11:32
Javascript flatMap implementation
// [B](f: (A) ⇒ [B]): [B] ; Although the types in the arrays aren't strict (:
Array.prototype.flatMap = function(lambda) {
return Array.prototype.concat.apply([], this.map(lambda));
};
@hugoferreira
hugoferreira / gist:4048818
Created November 9, 2012 22:45
Genetic Algorithms in Scala
import annotation.tailrec
import util.Random
object main extends App {
val target = "as armas e os baroes assinalados"
val genePool = Array('a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',' ')
def fitness(src: String): Double = src.zip(target).count { case (s, t) => s == t }
val petri = new GeneticExploration[Char, String](0.01, 500, genePool, cs => new String(cs.toArray), fitness, _.exists(_ == target))
@etorreborre
etorreborre / gist:3870064
Created October 11, 2012 03:54
Unboxed union types with a context bound
/**
* this is an experiment to create unboxed union types with a phantom type and a context bound.
* All the good ideas come from @milessabin post, comments and links: http://www.chuusai.com/2011/06/09/scala-union-types-curry-howard/#comment-22
*/
/** trait for anything that can be A or B */
trait Or[A, B] {
// a phantom type, there will be no instance of this type that we'll use
type l[T]
// an alias for l[t]
@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
@milessabin
milessabin / gist:2500326
Created April 26, 2012 15:22
Scala collection extension methods made easy (dependent types FTW!)
/*
* Copyright (c) 2012 Miles Sabin
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
@viktorklang
viktorklang / ScalaEnum.scala
Created June 30, 2011 23:12
DIY Scala Enums (with optional exhaustiveness checking)
trait Enum { //DIY enum type
import java.util.concurrent.atomic.AtomicReference //Concurrency paranoia
type EnumVal <: Value //This is a type that needs to be found in the implementing class
private val _values = new AtomicReference(Vector[EnumVal]()) //Stores our enum values
//Adds an EnumVal to our storage, uses CCAS to make sure it's thread safe, returns the ordinal
private final def addEnumVal(newVal: EnumVal): Int = { import _values.{get, compareAndSet => CAS}
val oldVec = get