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(ns shades.lenses)

; We only need three fns that know the structure of a lens.
(defn lens [focus fmap] {:focus focus :fmap fmap})
(defn view [x {:keys [focus]}] (focus x))
(defn update [x {:keys [fmap]} f] (fmap f x))

; The identity lens.
(defn fapply [f x] (f x))
(def id (lens identity fapply))

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; Comments start with semicolons.

; Clojure is written in "forms", which are just
; lists of things inside parentheses, separated by whitespace.
;
; The clojure reader  assumes that the first thing is a
; function or macro to call, and the rest are arguments.
;
; Here's a function that sets the current namespace:
(ns test)

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(ns sudoku
  (:refer-clojure :exclude [==])
  (:use clojure.core.logic))

(defn get-square [rows x y]
  (for [x (range x (+ x 3))
        y (range y (+ y 3))]
    (get-in rows [x y])))

(defn init [vars hints]

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Organizing Clojure Projects

Presented by @stuartsierra

Stuart presented using a deck created with org-html-slideshow, a Clojure library for formatting org-mode notes as HTML slides.

General Code Structure / Organization

1. Be careful not to make function calls across component boundaries.
2. Protocols should be minimalistic. They should have the fundamental operations of your component.

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;; Datomic example code
;;
;; The extent of entity ?x is all datoms that are about ?x.
;; Drop this into your rules.
;;
;; Demonstrates
;;
;; 1. recursive query (extent calls itself)
;; 2. disjunction (different extent bodies are ORed)
;; 3. component attributes (e.g. your arm is a component, your brother isn't)

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;; Datomic example code
(use '[datomic.api :only (db q) :as d])

;; ?answer binds a scalar
(q '[:find ?answer :in ?answer]
   42)

;; of course you can bind more than one of anything
(q '[:find ?last ?first :in ?last ?first]
   "Doe" "John")

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;; lein settings
(defproject foo "1.0.0-SNAPSHOT"
  :description "Test App"
  :dependencies [[com.datomic/datomic "0.1.2678"]
                 [frinj "0.1.2" :exclusions [org.clojure/clojure]]])

;; load libs
(use 'frinj.core 'frinj.calc)
(frinj-init!)
(use '[datomic.api :only (q db) :as d])

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;; A Simplifier for all Expressions

;; Example:
;; (simplify '(* 1 (+ x (- y y)))) ;=> x
;; (simplify '(and a (and (and) b))) ;=> (and a b)

;; See section 4.4, "Syntactic Abstraction" of Norvig and Pitman's
;; "Tutorial on Good Lisp Programming Style":
;; http://norvig.com/luv-slides.ps

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(ns hierarchy.core
  (:refer-clojure :exclude [==])
  (:use [clojure.core.logic]))

(def order [:domain :kingdom :phylum :class :order :family :genus :species])

(def homo-sapiens
  {:domain :eukarya
   :kingdom :animalia-metazoa
   :phylum :chordata

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;; Evolving a logic programming language
;; Based on sketches at https://github.com/frenchy64/Logic-Starter/blob/master/src/logic_introduction/decl_model.clj

;; A logic statement reduces to true or false.

true
;=> true

false
;=> false