Move example sources to separate dir.

15 files changed, 1731 insertions, 0 deletions

diff --git a/src/examples/clojure/clojure/contrib/accumulators/examples.clj b/src/examples/clojure/clojure/contrib/accumulators/examples.clj
new file mode 100644
index 00000000..b9dcbee5
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/accumulators/examples.clj
@@ -0,0 +1,93 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Accumulator application examples
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(ns
+  #^{:author "Konrad Hinsen"
+     :skip-wiki true
+     :doc "Examples for using accumulators"}
+  clojure.contrib.accumulators.examples
+  (:use [clojure.contrib.accumulators
+	 :only (combine add add-items
+		empty-vector empty-list empty-queue empty-set empty-map
+		empty-counter empty-counter-with-total
+		empty-sum empty-product empty-maximum empty-minimum
+		empty-min-max empty-mean-variance empty-string empty-tuple)]))
+
+; Vector accumulator: combine is concat, add is conj
+(combine [:a :b] [:c :d] [:x :y])
+(add [:a :b] :c)
+(add-items empty-vector [:a :b :a])
+
+; List accumulator: combine is concat, add is conj
+(combine '(:a :b) '(:c :d) '(:x :y))
+(add '(:a :b) :c)
+(add-items empty-list [:a :b :a])
+
+; Queue accumulator
+(let [q1 (add-items empty-queue [:a :b :a])
+      q2 (add-items empty-queue [:x :y])]
+  (combine q1 q2))
+
+; Set accumulator: combine is union, add is conj
+(combine #{:a :b} #{:c :d} #{:a :d})
+(add #{:a :b} :c)
+(add-items empty-set [:a :b :a])
+
+; Map accumulator: combine is merge, add is conj
+(combine {:a 1} {:b 2 :c 3} {})
+(add {:a 1} [:b 2])
+(add-items empty-map [[:a 1] [:b 2] [:a 0]])
+
+; Counter accumulator
+(let [c1 (add-items empty-counter [:a :b :a])
+      c2 (add-items empty-counter [:x :y])]
+  (combine c1 c2))
+
+; Counter-with-total accumulator
+(let [c1 (add-items empty-counter-with-total [:a :b :a])
+      c2 (add-items empty-counter-with-total [:x :y])]
+  (combine c1 c2))
+
+; Sum accumulator: combine is addition
+(let [s1 (add-items empty-sum [1 2 3])
+      s2 (add-items empty-sum [-1 -2 -3])]
+  (combine s1 s2))
+
+; Product accumulator: combine is multiplication
+(let [p1 (add-items empty-product [2 3])
+      p2 (add-items empty-product [(/ 1 2)])]
+  (combine p1 p2))
+
+; Maximum accumulator: combine is max
+(let [m1 (add-items empty-maximum [2 3])
+      m2 (add-items empty-maximum [(/ 1 2)])]
+  (combine m1 m2))
+
+; Minimum accumulator: combine is min
+(let [m1 (add-items empty-minimum [2 3])
+      m2 (add-items empty-minimum [(/ 1 2)])]
+  (combine m1 m2))
+
+; Min-max accumulator: combination of minimum and maximum
+(let [m1 (add-items empty-min-max [2 3])
+      m2 (add-items empty-min-max [(/ 1 2)])]
+  (combine m1 m2))
+
+; Mean-variance accumulator: sample mean and sample variance
+(let [m1 (add-items empty-mean-variance [2 4])
+      m2 (add-items empty-mean-variance [6])]
+  (combine m1 m2))
+
+; String accumulator: combine is concatenation
+(combine "a" "b" "c" "def")
+(add "a" (char 44))
+(add-items empty-string [(char 55) (char 56) (char 57)])
+
+; Accumulator tuples permit to update several accumulators in parallel
+(let [pair (empty-tuple [empty-vector empty-string])]
+  (add-items pair [[1 "a"] [2 "b"]]))
diff --git a/src/examples/clojure/clojure/contrib/condition/example.clj b/src/examples/clojure/clojure/contrib/condition/example.clj
new file mode 100644
index 00000000..5a7d72ef
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/condition/example.clj
@@ -0,0 +1,66 @@
+;;  Copyright (c) Stephen C. Gilardi. All rights reserved.  The use and
+;;  distribution terms for this software are covered by the Eclipse Public
+;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can
+;;  be found in the file epl-v10.html at the root of this distribution.  By
+;;  using this software in any fashion, you are agreeing to be bound by the
+;;  terms of this license.  You must not remove this notice, or any other,
+;;  from this software.
+;;
+;;  clojure.contrib.condition.example.clj
+;;
+;;  scgilardi (gmail)
+;;  Created 09 June 2009
+
+(ns clojure.contrib.condition.example
+  (:use (clojure.contrib
+         [condition
+          :only (handler-case print-stack-trace raise *condition*)])))
+
+(defn func [x y]
+  "Raises an exception if x is negative"
+  (when (neg? x)
+    (raise :type :illegal-argument :arg 'x :value x))
+  (+ x y))
+
+(defn main
+  []
+  
+  ;; simple handler
+  
+  (handler-case :type
+    (println (func 3 4))
+    (println (func -5 10))
+    (handle :illegal-argument
+            (print-stack-trace *condition*))
+    (println 3))
+
+  ;; multiple handlers
+  
+  (handler-case :type
+    (println (func 4 1))
+    (println (func -3 22))
+    (handle :overflow
+      (print-stack-trace *condition*))
+    (handle :illegal-argument
+      (print-stack-trace *condition*)))
+
+  ;; nested handlers
+
+  (handler-case :type
+    (handler-case :type
+      nil
+      nil
+      (println 1)
+      (println 2)
+      (println 3)
+      (println (func 8 2))
+      (println (func -6 17))
+      ;; no handler for :illegal-argument
+      (handle :overflow
+        (println "nested")
+        (print-stack-trace *condition*)))
+    (println (func 3 4))
+    (println (func -5 10))
+    (handle :illegal-argument
+      (println "outer")
+      (print-stack-trace *condition*))))
diff --git a/src/examples/clojure/clojure/contrib/datalog/example.clj b/src/examples/clojure/clojure/contrib/datalog/example.clj
new file mode 100644
index 00000000..88fcf961
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/datalog/example.clj
@@ -0,0 +1,116 @@
+;;  Copyright (c) Jeffrey Straszheim. All rights reserved.  The use and
+;;  distribution terms for this software are covered by the Eclipse Public
+;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can
+;;  be found in the file epl-v10.html at the root of this distribution.  By
+;;  using this software in any fashion, you are agreeing to be bound by the
+;;  terms of this license.  You must not remove this notice, or any other,
+;;  from this software.
+;;
+;;  example.clj
+;;
+;;  A Clojure implementation of Datalog - Example
+;;
+;;  straszheimjeffrey (gmail)
+;;  Created 2 March 2009
+
+
+(ns clojure.contrib.datalog.example
+  (:use [clojure.contrib.datalog :only (build-work-plan run-work-plan)]
+        [clojure.contrib.datalog.rules :only (<- ?- rules-set)]
+        [clojure.contrib.datalog.database :only (make-database add-tuples)]
+        [clojure.contrib.datalog.util :only (*trace-datalog*)]))
+
+
+
+
+(def db-base
+     (make-database
+      (relation :employee [:id :name :position])
+      (index :employee :name)
+
+      (relation :boss [:employee-id :boss-id])
+      (index :boss :employee-id)
+
+      (relation :can-do-job [:position :job])
+      (index :can-do-job :position)
+
+      (relation :job-replacement [:job :can-be-done-by])
+      ;(index :job-replacement :can-be-done-by)
+
+      (relation :job-exceptions [:id :job])))
+
+(def db
+     (add-tuples db-base
+           [:employee :id 1  :name "Bob"    :position :boss]
+           [:employee :id 2  :name "Mary"   :position :chief-accountant]
+           [:employee :id 3  :name "John"   :position :accountant]
+           [:employee :id 4  :name "Sameer" :position :chief-programmer]
+           [:employee :id 5  :name "Lilian" :position :programmer]
+           [:employee :id 6  :name "Li"     :position :technician]
+           [:employee :id 7  :name "Fred"   :position :sales]
+           [:employee :id 8  :name "Brenda" :position :sales]
+           [:employee :id 9  :name "Miki"   :position :project-management]
+           [:employee :id 10 :name "Albert" :position :technician]
+           
+           [:boss :employee-id 2  :boss-id 1]
+           [:boss :employee-id 3  :boss-id 2]
+           [:boss :employee-id 4  :boss-id 1]
+           [:boss :employee-id 5  :boss-id 4]
+           [:boss :employee-id 6  :boss-id 4]
+           [:boss :employee-id 7  :boss-id 1]
+           [:boss :employee-id 8  :boss-id 7]
+           [:boss :employee-id 9  :boss-id 1]
+           [:boss :employee-id 10 :boss-id 6]
+
+           [:can-do-job :position :boss               :job :management]
+           [:can-do-job :position :accountant         :job :accounting]
+           [:can-do-job :position :chief-accountant   :job :accounting]
+           [:can-do-job :position :programmer         :job :programming]
+           [:can-do-job :position :chief-programmer   :job :programming]           
+           [:can-do-job :position :technician         :job :server-support]
+           [:can-do-job :position :sales              :job :sales]
+           [:can-do-job :position :project-management :job :project-management]
+
+           [:job-replacement :job :pc-support :can-be-done-by :server-support]
+           [:job-replacement :job :pc-support :can-be-done-by :programming]
+           [:job-replacement :job :payroll    :can-be-done-by :accounting]
+
+           [:job-exceptions :id 4 :job :pc-support]))
+
+(def rules
+     (rules-set
+        (<- (:works-for :employee ?x :boss ?y) (:boss :employee-id ?e-id :boss-id ?b-id)
+                                               (:employee :id ?e-id :name ?x)
+                                               (:employee :id ?b-id :name ?y))
+        (<- (:works-for :employee ?x :boss ?y) (:works-for :employee ?x :boss ?z)
+                                               (:works-for :employee ?z :boss ?y))
+        (<- (:employee-job* :employee ?x :job ?y) (:employee :name ?x :position ?pos)
+                                                  (:can-do-job :position ?pos :job ?y))
+        (<- (:employee-job* :employee ?x :job ?y) (:job-replacement :job ?y :can-be-done-by ?z)
+                                                  (:employee-job* :employee ?x  :job ?z))
+        (<- (:employee-job* :employee ?x :job ?y) (:can-do-job :job ?y)
+                                                  (:employee :name ?x :position ?z)
+                                                  (if = ?z :boss))
+        (<- (:employee-job :employee ?x :job ?y) (:employee-job* :employee ?x :job ?y)
+                                                 (:employee :id ?id :name ?x)
+                                                 (not! :job-exceptions :id ?id :job ?y))
+        (<- (:bj :name ?x :boss ?y) (:works-for :employee ?x :boss ?y)
+                                    (not! :employee-job :employee ?y :job :pc-support))))
+
+
+
+(def wp-1 (build-work-plan rules (?- :works-for :employee '??name :boss ?x)))
+(run-work-plan wp-1 db {'??name "Albert"})
+
+(def wp-2 (build-work-plan rules (?- :employee-job :employee '??name :job ?x)))
+(binding [*trace-datalog* true]
+  (run-work-plan wp-2 db {'??name "Li"}))
+
+(def wp-3 (build-work-plan rules (?- :bj :name '??name :boss ?x)))
+(run-work-plan wp-3 db {'??name "Albert"})
+
+(def wp-4 (build-work-plan rules (?- :works-for :employee ?x :boss ?y)))
+(run-work-plan wp-4 db {})
+
+
+;; End of file
diff --git a/src/examples/clojure/clojure/contrib/miglayout/example.clj b/src/examples/clojure/clojure/contrib/miglayout/example.clj
new file mode 100644
index 00000000..c688e9fe
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/miglayout/example.clj
@@ -0,0 +1,60 @@
+;;  Copyright (c) Stephen C. Gilardi. All rights reserved.  The use and
+;;  distribution terms for this software are covered by the Eclipse Public
+;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can
+;;  be found in the file epl-v10.html at the root of this distribution.  By
+;;  using this software in any fashion, you are agreeing to be bound by the
+;;  terms of this license.  You must not remove this notice, or any other,
+;;  from this software.
+;;
+;;  clojure.contrib.miglayout.example
+;;
+;;  A temperature converter using miglayout. Demonstrates accessing
+;;  components by their id constraint.
+;;
+;;  scgilardi (gmail)
+;;  Created 31 May 2009
+
+(ns clojure.contrib.miglayout.example
+  (:import (javax.swing JButton JFrame JLabel JPanel JTextField
+                        SwingUtilities))
+  (:use (clojure.contrib
+         [miglayout :only (miglayout components)]
+         [swing-utils :only (add-key-typed-listener)])))
+
+(defn fahrenheit
+  "Converts a Celsius temperature to Fahrenheit. Input and output are
+  strings. Returns \"input?\" if the input can't be parsed as a Double."
+  [celsius]
+  (try
+   (format "%.2f" (+ 32 (* 1.8 (Double/parseDouble celsius))))
+   (catch NumberFormatException _ "input?")))
+
+(defn- handle-key
+  "Clears output on most keys, shows conversion on \"Enter\""
+  [event out]
+  (.setText out
+    (if (= (.getKeyChar event) \newline)
+      (fahrenheit (-> event .getComponent .getText))
+      "")))
+
+(defn converter-ui
+  "Lays out and shows a Temperature Converter UI"
+  []
+  (let [panel
+        (miglayout (JPanel.)
+         (JTextField. 6) {:id :input}
+         (JLabel. "\u00b0Celsius") :wrap
+         (JLabel.) {:id :output}
+         (JLabel. "\u00b0Fahrenheit"))
+        {:keys [input output]} (components panel)]
+    (add-key-typed-listener input handle-key output)
+    (doto (JFrame. "Temperature Converter")
+      (.setDefaultCloseOperation JFrame/DISPOSE_ON_CLOSE)
+      (.add panel)
+      (.pack)
+      (.setVisible true))))
+
+(defn main
+  "Invokes converter-ui in the AWT Event thread"
+  []
+  (SwingUtilities/invokeLater converter-ui))
diff --git a/src/examples/clojure/clojure/contrib/monads/examples.clj b/src/examples/clojure/clojure/contrib/monads/examples.clj
new file mode 100644
index 00000000..00e5dfaf
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/monads/examples.clj
@@ -0,0 +1,425 @@
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Monad application examples
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(ns
+  #^{:author "Konrad Hinsen"
+     :skip-wiki true
+     :doc "Examples for using monads"}
+  clojure.contrib.monads.examples
+  (:use [clojure.contrib.monads
+	 :only (domonad with-monad m-lift m-seq m-reduce m-when
+		sequence-m
+		maybe-m
+		state-m fetch-state set-state 
+		writer-m write
+		cont-m run-cont call-cc
+		maybe-t)])
+  (:require (clojure.contrib [accumulators :as accu])))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;;  Sequence manipulations with the sequence monad
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; Note: in the Haskell world, this monad is called the list monad.
+; The Clojure equivalent to Haskell's lists are (possibly lazy)
+; sequences. This is why I call this monad "sequence". All sequences
+; created by sequence monad operations are lazy.
+
+; Monad comprehensions in the sequence monad work exactly the same
+; as Clojure's 'for' construct, except that :while clauses are not
+; available.
+(domonad sequence-m
+   [x (range 5)
+    y (range 3)]
+    (+ x y))
+
+; Inside a with-monad block, domonad is used without the monad name.
+(with-monad sequence-m
+  (domonad
+     [x (range 5)
+      y (range 3)]
+     (+ x y)))
+
+; Conditions are written with :when, as in Clojure's for form:
+(domonad sequence-m
+   [x  (range 5)
+    y  (range (+ 1 x))
+    :when (= (+ x y) 2)]
+   (list x y))
+
+; :let is also supported like in for:
+(domonad sequence-m
+   [x  (range 5)
+    y  (range (+ 1 x))
+    :let [sum (+ x y)
+	  diff (- x y)]
+    :when  (= sum 2)]
+   (list diff))
+
+; An example of a sequence function defined in terms of a lift operation.
+(with-monad sequence-m
+   (defn pairs [xs]
+      ((m-lift 2 #(list %1 %2)) xs xs)))
+
+(pairs (range 5))
+
+; Another way to define pairs is through the m-seq operation. It takes
+; a sequence of monadic values and returns a monadic value containing
+; the sequence of the underlying values, obtained from chaining together
+; from left to right the monadic values in the sequence.
+(with-monad sequence-m
+   (defn pairs [xs]
+      (m-seq (list xs xs))))
+
+(pairs (range 5))
+
+; This definition suggests a generalization:
+(with-monad sequence-m
+   (defn ntuples [n xs]
+      (m-seq (replicate n xs))))
+
+(ntuples 2 (range 5))
+(ntuples 3 (range 5))
+
+; Lift operations can also be used inside a monad comprehension:
+(domonad sequence-m
+   [x  ((m-lift 1 (partial * 2)) (range 5))
+    y  (range 2)]
+    [x y])
+
+; The m-plus operation does concatenation in the sequence monad.
+(domonad sequence-m
+   [x  ((m-lift 2 +) (range 5) (range 3))
+    y  (m-plus (range 2) '(10 11))]
+   [x y])
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Handling failures with the maybe monad
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; Maybe monad versions of basic arithmetic
+(with-monad maybe-m
+   (def m+ (m-lift 2 +))
+   (def m- (m-lift 2 -))
+   (def m* (m-lift 2 *)))
+
+; Division is special for two reasons: we can't call it m/ because that's
+; not a legal Clojure symbol, and we want it to fail if a division by zero
+; is attempted. It is best defined by a monad comprehension with a
+; :when clause:
+(defn safe-div [x y]
+  (domonad maybe-m
+     [a x
+      b y
+      :when (not (zero? b))]
+     (/ a b)))
+
+; Now do some non-trivial computation with division
+; It fails for (1) x = 0, (2) y = 0 or (3) y = -x.
+(with-monad maybe-m
+   (defn some-function [x y]
+      (let [one (m-result 1)]
+ 	   (safe-div one (m+ (safe-div one (m-result x))
+			     (safe-div one (m-result y)))))))
+
+; An example that doesn't fail:
+(some-function 2 3)
+; And two that do fail, at different places:
+(some-function 2 0)
+(some-function 2 -2)
+
+; In the maybe monad, m-plus selects the first monadic value that
+; holds a valid value.
+(with-monad maybe-m
+   (m-plus (some-function 2 0) (some-function 2 -2) (some-function 2 3)))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;;  Random numbers with the state monad
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; A state monad item represents a computation that changes a state and
+; returns a value. Its structure is a function that takes a state argument
+; and returns a two-item list containing the value and the updated state.
+; It is important to realize that everything you put into a state monad
+; expression is a state monad item (thus a function), and everything you
+; get out as well. A state monad does not perform a calculation, it
+; constructs a function that does the computation when called.
+
+; First, we define a simple random number generator with explicit state.
+; rng is a function of its state (an integer) that returns the
+; pseudo-random value derived from this state and the updated state 
+; for the next iteration. This is exactly the structure of a state
+;  monad item.
+(defn rng [seed]
+  (let [m      259200
+	value  (/ (float seed) (float m))
+	next   (rem (+ 54773 (* 7141 seed)) m)]
+    [value next]))
+
+; We define a convenience function that creates an infinite lazy seq
+; of values obtained from iteratively applying a state monad value.
+(defn value-seq [f seed]
+  (lazy-seq
+    (let [[value next] (f seed)]
+      (cons value (value-seq f next)))))
+
+; Next, we define basic statistics functions to check our random numbers
+(defn sum [xs]  (apply + xs))
+(defn mean [xs]  (/ (sum xs) (count xs)))
+(defn variance [xs]
+  (let [m (mean xs)
+	sq #(* % %)]
+    (mean (for [x xs] (sq (- x m))))))
+
+; rng implements a uniform distribution in the interval [0., 1.), so
+; ideally, the mean would be 1/2 (0.5) and the variance 1/12 (0.8333).
+(mean (take 1000 (value-seq rng 1)))
+(variance (take 1000 (value-seq rng 1)))
+
+; We make use of the state monad to implement a simple (but often sufficient)
+; approximation to a Gaussian distribution: the sum of 12 random numbers
+; from rng's distribution, shifted by -6, has a distribution that is
+; approximately Gaussian with 0 mean and variance 1, by virtue of the central
+; limit theorem.
+; In the first version, we call rng 12 times explicitly and calculate the
+; shifted sum in a monad comprehension:
+(def gaussian1
+   (domonad state-m
+      [x1  rng
+       x2  rng
+       x3  rng
+       x4  rng
+       x5  rng
+       x6  rng
+       x7  rng
+       x8  rng
+       x9  rng
+       x10 rng
+       x11 rng
+       x12 rng]
+      (- (+ x1 x2 x3 x4 x5 x6 x7 x8 x9 x10 x11 x12) 6.)))
+
+; Let's test it:
+(mean (take 1000 (value-seq gaussian1 1)))
+(variance (take 1000 (value-seq gaussian1 1)))
+
+; Of course, we'd rather have a loop construct for creating the 12
+; random numbers. This would be easy if we could define a summation
+; operation on random-number generators, which would then be used in
+; combination with reduce. The lift operation gives us exactly that.
+; More precisely, we need (m-lift 2 +), because we want both arguments
+; of + to be lifted to the state monad:
+(def gaussian2
+   (domonad state-m
+      [sum12 (reduce (m-lift 2 +) (replicate 12 rng))]
+      (- sum12 6.)))
+
+; Such a reduction is often quite useful, so there's m-reduce predefined
+; to simplify it:
+(def gaussian2
+   (domonad state-m
+      [sum12 (m-reduce + (replicate 12 rng))]
+      (- sum12 6.)))
+
+; The statistics should be strictly the same as above, as long as
+; we use the same seed:
+(mean (take 1000 (value-seq gaussian2 1)))
+(variance (take 1000 (value-seq gaussian2 1)))
+
+; We can also do the subtraction of 6 in a lifted function, and get rid
+; of the monad comprehension altogether:
+(with-monad state-m
+   (def gaussian3
+        ((m-lift 1 #(- % 6.))
+           (m-reduce + (replicate 12 rng)))))
+
+; Again, the statistics are the same:
+(mean (take 1000 (value-seq gaussian3 1)))
+(variance (take 1000 (value-seq gaussian3 1)))
+
+; For a random point in two dimensions, we'd like a random number generator
+; that yields a list of two random numbers. The m-seq operation can easily
+; provide it:
+(with-monad state-m
+   (def rng2 (m-seq (list rng rng))))
+
+; Let's test it:
+(rng2 1)
+
+; fetch-state and get-state can be used to save the seed of the random
+; number generator and go back to that saved seed later on:
+(def identical-random-seqs
+  (domonad state-m
+    [seed (fetch-state)
+     x1   rng
+     x2   rng
+     _    (set-state seed)
+     y1   rng
+     y2   rng]
+    (list [x1 x2] [y1 y2])))
+
+(identical-random-seqs 1)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;;  Logging with the writer monad
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; A basic logging example
+(domonad (writer-m accu/empty-string)
+  [x (m-result 1)
+   _ (write "first step\n")
+   y (m-result 2)
+   _ (write "second step\n")]
+  (+ x y))
+
+; For a more elaborate application, let's trace the recursive calls of
+; a naive implementation of a Fibonacci function. The starting point is:
+(defn fib [n]
+  (if (< n 2)
+    n
+    (let [n1 (dec n)
+	  n2 (dec n1)]
+      (+ (fib n1) (fib n2)))))
+
+; First we rewrite it to make every computational step explicit
+; in a let expression:
+(defn fib [n]
+  (if (< n 2)
+    n
+    (let [n1 (dec n)
+	  n2 (dec n1)
+	  f1 (fib n1)
+	  f2 (fib n2)]
+      (+ f1 f2))))
+
+; Next, we replace the let by a domonad in a writer monad that uses a
+; vector accumulator. We can then place calls to write in between the
+; steps, and obtain as a result both the return value of the function
+; and the accumulated trace values.
+(with-monad (writer-m accu/empty-vector)
+
+  (defn fib-trace [n]
+    (if (< n 2)
+      (m-result n)
+      (domonad
+        [n1 (m-result (dec n))
+	 n2 (m-result (dec n1))
+	 f1 (fib-trace n1)
+	 _  (write [n1 f1])
+	 f2 (fib-trace n2)
+	 _  (write [n2 f2])
+	 ]
+	(+ f1 f2))))
+
+)
+
+(fib-trace 5)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Sequences with undefined value: the maybe-t monad transformer
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; A monad transformer is a function that takes a monad argument and
+; returns a monad as its result. The resulting monad adds some
+; specific behaviour aspect to the input monad.
+
+; The simplest monad transformer is maybe-t. It adds the functionality
+; of the maybe monad (handling failures or undefined values) to any other
+; monad. We illustrate this by applying maybe-t to the sequence monad.
+; The result is an enhanced sequence monad in which undefined values
+; (represented by nil) are not subjected to any transformation, but
+; lead immediately to a nil result in the output.
+
+; First we define the combined monad:
+(def seq-maybe-m (maybe-t sequence-m))
+
+; As a first illustration, we create a range of integers and replace
+; all even values by nil, using a simple when expression. We use this
+; sequence in a monad comprehension that yields (inc x). The result
+; is a sequence in which inc has been applied to all non-nil values,
+; whereas the nil values appear unmodified in the output:
+(domonad seq-maybe-m
+  [x  (for [n (range 10)] (when (odd? n) n))]
+  (inc x))
+
+; Next we repeat the definition of the function pairs (see above), but
+; using the seq-maybe monad:
+(with-monad seq-maybe-m
+   (defn pairs-maybe [xs]
+      (m-seq (list xs xs))))
+
+; Applying this to a sequence containing nils yields the pairs of all
+; non-nil values interspersed with nils that result from any combination
+; in which one or both of the values is nil:
+(pairs-maybe (for [n (range 5)] (when (odd? n) n)))
+
+; It is important to realize that undefined values (nil) are not eliminated
+; from the iterations. They are simply not passed on to any operations.
+; The outcome of any function applied to arguments of which at least one
+; is nil is supposed to be nil as well, and the function is never called.
+
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; Continuation-passing style in the cont monad
+;;
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+; A simple computation performed in continuation-passing style.
+; (m-result 1) returns a function that, when called with a single
+; argument f, calls (f 1). The result of the domonad-computation is
+; a function that behaves in the same way, passing 3 to its function
+; argument. run-cont executes a continuation by calling it on identity.
+(run-cont
+  (domonad cont-m
+    [x (m-result 1)
+     y (m-result 2)]
+    (+ x y)))
+
+; Let's capture a continuation using call-cc. We store it in a global
+; variable so that we can do with it whatever we want. The computation
+; is the same one as in the first example, but it has the side effect
+; of storing the continuation at (m-result 2).
+(def continuation nil)
+
+(run-cont
+  (domonad cont-m
+    [x (m-result 1)
+     y (call-cc (fn [c] (def continuation c) (c 2)))]
+    (+ x y)))
+
+; Now we can call the continuation with whatever argument we want. The
+; supplied argument takes the place of 2 in the above computation:
+(run-cont (continuation 5))
+(run-cont (continuation 42))
+(run-cont (continuation -1))
+
+; Next, a function that illustrates how a captured continuation can be
+; used as an "emergency exit" out of a computation:
+(defn sqrt-as-str [x]
+  (call-cc
+   (fn [k]
+     (domonad cont-m
+       [_ (m-when (< x 0) (k (str "negative argument " x)))]
+       (str (. Math sqrt x))))))
+
+(run-cont (sqrt-as-str 2))
+(run-cont (sqrt-as-str -2))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
diff --git a/src/examples/clojure/clojure/contrib/pprint/examples/hexdump.clj b/src/examples/clojure/clojure/contrib/pprint/examples/hexdump.clj
new file mode 100644
index 00000000..fa5316ec
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/pprint/examples/hexdump.clj
@@ -0,0 +1,63 @@
+;;; hexdump.clj -- part of the pretty printer for Clojure
+
+;; by Tom Faulhaber
+;; April 3, 2009
+
+;   Copyright (c) Tom Faulhaber, Dec 2008. All rights reserved.
+;   The use and distribution terms for this software are covered by the
+;   Eclipse Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;   which can be found in the file epl-v10.html at the root of this distribution.
+;   By using this software in any fashion, you are agreeing to be bound by
+;   the terms of this license.
+;   You must not remove this notice, or any other, from this software.
+
+;; This example is a classic hexdump program written using cl-format.
+
+;; For some local color, it was written in Dulles Airport while waiting for a flight
+;; home to San Francisco.
+
+(ns clojure.contrib.pprint.examples.hexdump
+  (:use clojure.contrib.pprint
+        clojure.contrib.pprint.utilities)
+  (:gen-class (:main true)))
+
+(def *buffer-length* 1024)
+
+(defn zip-array [base-offset arr]
+  (let [grouped (partition 16 arr)]
+    (first (map-passing-context
+            (fn [line offset]
+              [[offset 
+                (map #(if (neg? %) (+ % 256) %) line)
+                (- 16 (count line))
+                (map #(if (<= 32 % 126) (char %) \.) line)]
+               (+ 16 offset)])
+            base-offset grouped))))
+
+
+(defn hexdump 
+  ([in-stream] (hexdump in-stream true 0))
+  ([in-stream out-stream] (hexdump [in-stream out-stream 0]))
+  ([in-stream out-stream offset] 
+     (let [buf (make-array Byte/TYPE *buffer-length*)]
+       (loop [offset offset
+              count (.read in-stream buf)]
+         (if (neg? count)
+           nil
+           (let [bytes (take count buf)
+                 zipped (zip-array offset bytes)]
+             (cl-format out-stream 
+                        "~:{~8,'0X: ~2{~8@{~#[   ~:;~2,'0X ~]~}  ~}~v@{   ~}~2{~8@{~A~} ~}~%~}" 
+                        zipped) 
+             (recur (+ offset *buffer-length*) (.read in-stream buf))))))))
+
+(defn hexdump-file 
+  ([file-name] (hexdump-file file-name true))
+  ([file-name stream] 
+     (with-open [s (java.io.FileInputStream. file-name)] 
+       (hexdump s))))
+
+;; I don't quite understand how to invoke main funcs w/o AOT yet
+(defn -main [& args]
+  (hexdump-file (first args)))
+
diff --git a/src/examples/clojure/clojure/contrib/pprint/examples/json.clj b/src/examples/clojure/clojure/contrib/pprint/examples/json.clj
new file mode 100644
index 00000000..3cde1751
--- /dev/null
+++ b/src/examples/clojure/clojure/contrib/pprint/examples/json.clj
@@ -0,0 +1,142 @@
+;;; json.clj: A pretty printing version of the JavaScript Object Notation (JSON) generator
+
+;; by Tom Faulhaber, based on the version by Stuart Sierra (clojure.contrib.json.write)
+;; May 9, 2009
+
+;; Copyright (c) Tom Faulhaber/Stuart Sierra, 2009. All rights reserved.  The use
+;; and distribution terms for this software are covered by the Eclipse
+;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
+;; which can be found in the file epl-v10.html at the root of this
+;; distribution.  By using this software in any fashion, you are
+;; agreeing to be bound by the terms of this license.  You must not
+;; remove this notice, o