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@daveyarwood
Created March 6, 2014 11:25
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; ex. 1:
(defn dr-chams-timeline [year]
(cond
(= year 1894)
"Born."
(<= 1895 year 1913)
"Childhood in Louisville, Winston Co., Mississippi."
(<= 1914 year 1919)
"Worked at a pecan nursery; punched a Quaker."
(<= 1920 year 1928)
(str "Sailed in the Brotherhood of River Wisdomming, which journeyed the Mississippi "
"River and engaged in thoughtful self-improvement, where he finished 140 credit "
"hours from their Oarniversity.")
(= year 1929)
"Returned to Louisville to pen a novel about time-travelling pheasant hunters."
(<= 1930 year 1933)
(str "Took up a respectable career insuring pecan nurseries. Financially stable, he "
"spent time in Brazil and New Mexico, buying up rare paper-shell pecan trees. "
"Just as his notoriety came to a crescendo: gosh, he tried to bury himself "
"alive.")
(= year 1934)
(str "Went back to writing his novel. Changed the hunters to insurance tycoons and "
"the pheasants to Quakers.")
(<= 1935 year 1940)
(str "Took Arthur Cone, the Headmaster of the Brotherhood of River Wisdomming, as a "
"houseguest. Together for five years, engineering and inventing.")
(= year 1941)
"And this is where things got interesting."))
; ex. 2:
(dr-chams-timeline 1941)
; ex. 3:
(cond
(= year 1894) "Born."
(<= 1895 year 1913) "Childhood in Louisville, Winston-Co., Mississippi."
:else "No information about this year.")
; ex. 4:
(if (= 1894 year)
"Born."
(if (<= 1895 year 1913)
"Childhood in Louisville, Winston Co., Mississippi."
"No information about this year."))
; ex. 5:
(def opus-magnum true)
(defn save-hannah [] (let [success opus-magnum] nil))
; this doesn't really make sense, but then, the original Ruby example was just to
; demonstrate the lack of closures in Ruby
; ex. 6:
(def verb "rescued")
(doseq [verb ["sedated" "sprinkled" "electrocuted"]]
(println "Dr. Cham" verb "his niece Hannah."))
(println "Finally, Dr. Cham" verb "his niece Hannah.")
; ex. 7:
(doseq [verb ["sedated" "sprinkled" "electrocuted"]]
(println "Dr. Cham" verb "his niece Hannah."))
(println "Finally, Dr. Cham" verb "his niece Hannah.")
; results in an error, just like the Ruby example
; ex. 8:
(require '[endertromb.core :as endertromb])
(defprotocol WishMaking
(grant [wm wish] "Grants a wish."))
(defrecord WishMaker [energy]
WishMaking
(grant [_ wish]
(cond
(or
(> (count wish) 10)
(re-find #" " wish))
(throw (IllegalArgumentException. "Bad wish."))
(zero? energy)
(throw (Exception. "No energy left."))
:else
(do
(endertromb/make wish)
(WishMaker. (dec energy))))))
; ex. 9:
(def todays-wishes (WishMaker. (rand-int 6)))
; ex. 10:
(def todays-wishes (WishMaker. (rand-int 6)))
(grant todays-wishes "antlers")
; ex. 11:
(def number 5)
(print (inc number))
(def phrase "wishing for antlers")
(print (count phrase))
(def today-wishes (WishMaker. (rand-int 6)))
(grant todays-wishes "antlers")
; ex. 12:
(print (type 5))
(print (type "wishing for antlers"))
(print (type (WishMaker. (rand-int 6))))
; ex. 13:
(require '[endertromb.core :as endertromb])
(defprotocol MindReading
(read [mr] "Reads minds."))
(defrecord MindReader [minds]
MindReading
(read [_] (map endertromb/read minds)))
; Ruby initialize method pulled out into the object instantiation:
(MindReader. (endertromb/scan-for-sentience))
; skipping all the irb stuff... (it's not relevant to Clojure)
; ex. 14:
(defprotocal Elevation
(maintenance-password [this] "Maintenance password.")
(authenticate [this password] "Checks password before operating."))
(defrecord Elevator [password]
Elevation
(maintenance-password [_] "stairs_are_history!")
(authenticate [_ password]
(when-not (= password maintenance-password)
(throw (Exception. "bad password")))))
; Other Elevator methods would call (authenticate [_ password]) before executing
; their functions. If the password checks out, it returns nil and the rest of the
; method will happily execute. Otherwise, an exception is thrown.
; ex. 15:
(defn wipe-mutterings-from [sentence]
(clojure.string/replace sentence #"\([^)]*\)" ""))
; ex. 16:
(def what-he-said
(str "But, strangely (em-pithy-dah), I learned upon, played upon (pon-shoo) "
"the organs on my home (oth-rea) planet."))
(wipe-mutterings-from what-he-said)
; ex. 17:
(defn wipe-mutterings-from [sentence]
(when-not (string? sentence)
(throw (IllegalArgumentException.
(str "cannot wipe mutterings from a " (type sentence)))))
(clojure.string/replace sentence #"\([^)]*\)" ""))
; ex. 18:
(def something-said "A (gith) spaceship.")
(wipe-mutterings-from something-said)
; ex. 19:
; (the "sentence = sentence.dup" example)
; there is no need to do this in Clojure, thanks to functional programming!
; ex. 20:
; (ditto)
; ex. 21:
(def s "A string is a long shelf of letters and spaces.")
(subs s 0 1) ; A
(subs s 0) ; A string is a long shelf of letters and spaces.
(apply str (drop 1 (drop-last 1 s))) ; (drops first and last character)
(subs s 0 3) ; A s
(re-find #"shelf" s) ; shelf
; ex. 22:
; (same as ex. 17)
; ex. 23:
(def muddy-stick "Here's a ( curve.")
(wipe-mutterings-from muddy-stick)
; not a problem for our functional implementation using clojure.string/replace!
; ex. 24:
; Bingo! Here, _why uses gsub/regexp to improve this method. This is practically the
; same thing as our clojure.string/replace solution; _why just used a slightly
; different regexp, \([-\w]+\) than I did. Mine's better, though ;)
; ex. 25:
; Clojure doesn't encourage monkey-patching, but implementing this is still trivial
; and quite readable using ordinary functions:
(defn name-significance [name]
(let [legend
{"Paij" "Personal", "Gonk" "Business",
"Blon" "Slave", "Stro" "Master",
"Wert" "Father", "Onnn" "Mother",
"ree" "AM", "plo" "PM"}
syllables (clojure.string/split name #"-")]
(clojure.string/join " " (map legend syllables))))
; BTW, you could technically "monkey-patch" the String type to add a
; "name-significance" method, extended from a protocol you create via Clojure's
; "extend-type" function, but the usage would be exactly the same:
; (name-significance "name"). So in this case, there isn't much point to using
; anything more complicated than an ordinary function.
; ex. 26:
(name-significance "Paij-ree")
; ex. 27:
; rather than monkey-patching, you could just do this:
(defn dash-split [s] (clojure.string/split s #"-"))
; if polymorphism is needed, you can use multimethods
; ex. 28:
(dash-split "Gonk-plo")
; ex. 29:
; (class String; def dash_split; split('-'); end; end)
; The equivalent to this in Clojure would involve using extend-type on Java's String
; class. It's not really necessary, though :)
; ex. 30:
; the equivalent part of our name-significance method is:
(map legend syllables)
; ex. 31:
(def cats-and-tips (map #(+ % (* % 0.20)) [0.12 0.63 0.09]))
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