owainlewis

-- Haskell Types

type Id   = Int
type Title = String
type Author = String

data Book = Book Id Title Author
            deriving (Eq, Show)

bookID :: Book -> Int

owainlewis

# A Binary Search Tree implementation in Ruby

require 'minitest/spec'
require 'minitest/autorun'

# ========================================
#
#         1
#        / \
#       /   \

owainlewis

# Returns new hash and leaves original as is
def select_from_param(hash, *args)
  {}.tap do |result|
    hash.each {|k, v| result[k] = v if args.include?(k)}
  end
end

@model.update_attributes(select_from_param(params, :id, :email))

owainlewis

module BinaryTree 
  where

-- Haskell Binary Tree Examples

-- A binary tree can either be empty or a node with a left and right branch

data Tree a = EmptyTree | Node a (Tree a) (Tree a)
  deriving ( Show, Read, Eq )

owainlewis

(ns forward.lib.validation
  (:refer-clojure :exclude []))

;; Generic map validation library

(def m
  {:first_name "jack"
   :last_name "dorsey"
   :password "twitter"
   :age 25})

owainlewis

(* Unbalanced Binary Tree *)
    
type 'a tree =
  Node of 'a * 'a tree * 'a tree
  | Leaf;;

(* e.g Node (5, Leaf, Leaf) *)

(* val insert : ’a -> ’a btree -> ’a btree = <fun> *)
let insert x s = Node (x, Leaf, s);;

owainlewis

(ns forward.views.helpers)

;; View helper functions

(defn flash-messages
  "Show flash messages if they exist in a request"
  [req]
  (declare flash-message)
  (if-let [flash-message (:flash req)]      
    [:div {:id "error_explanation"}

owainlewis

;; The following implementation of rb-tree is based on http://www.cs.kent.ac.uk/people/staff/smk/redblack/.

(defun change-to-black (tree)
  (pattern-match tree
    ((:pattern (_ . rest) :variable rest :ignore _) `(:B . ,rest))
    (:otherwise nil)))

(defun rb-insert (tree obj cmp)
  (change-to-black (rb-insert% tree obj cmp)))

owainlewis

import qualified Data.Map as M
import Control.Applicative
import Data.Maybe (mapMaybe)

-- A BK-Tree is has a root word and more trees connected to it with branches of
-- lengths equal to the Levenshtein distance between their root words (i.e. an
-- n-ary tree).
data BKTree s = BKTree s (M.Map Int (BKTree s)) | Empty deriving (Show)

-- Inserting a word is done by inserting it along a branch of lenght

owainlewis

(***************************************

 Binary Search Trees                 

***************************************)

(* insert delete inorder search min max *)
    
type 'a binary_tree =
  (* A root node and a left and right sub tree *)