This commit is contained in:
Artur Meyster 2016-08-08 17:33:58 +00:00 committed by GitHub
commit b6ecd8a6ec
7 changed files with 86 additions and 86 deletions

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(meditations (meditations
"We shall contemplate truth by testing reality, via equality" "We shall contemplate truth by testing reality, via equality"
(= __ true) (= true true)
"To understand reality, we must compare our expectations against reality" "To understand reality, we must compare our expectations against reality"
(= __ (+ 1 1)) (= 2 (+ 1 1))
"You can test equality of many things" "You can test equality of many things"
(= (+ 3 4) 7 (+ 2 __)) (= (+ 3 4) 7 (+ 2 5))
"Some things may appear different, but be the same" "Some things may appear different, but be the same"
(= __ (= 2 2/1)) (= true (= 2 2/1))
"You cannot generally float to heavens of integers" "You cannot generally float to heavens of integers"
(= __ (= 2 2.0)) (= false (= 2 2.0))
"But a looser equality is also possible" "But a looser equality is also possible"
(= __ (== 2.0 2)) (= true (== 2.0 2))
"Something is not equal to nothing" "Something is not equal to nothing"
(= __ (not (= 1 nil))) (= true (not (= 1 nil)))
"Strings, and keywords, and symbols: oh my!" "Strings, and keywords, and symbols: oh my!"
(= __ (= "hello" :hello 'hello)) (= false (= "hello" :hello 'hello))
"Make a keyword with your keyboard" "Make a keyword with your keyboard"
(= :hello (keyword __)) (= :hello (keyword "hello"))
"Symbolism is all around us" "Symbolism is all around us"
(= 'hello (symbol __)) (= 'hello (symbol "hello"))
"What could be equivalent to nothing?" "What could be equivalent to nothing?"
(= __ nil) (= __ nil)
"When things cannot be equal, they must be different" "When things cannot be equal, they must be different"
(not= :fill-in-the-blank __)) (not= :fill-in-the-blank :not-equal))

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@ -4,67 +4,67 @@
(meditations (meditations
"A string is nothing more than text surrounded by double quotes" "A string is nothing more than text surrounded by double quotes"
(= __ "hello") (= "hello" "hello")
"But double quotes are just magic on top of something deeper" "But double quotes are just magic on top of something deeper"
(= __ (str 'world)) (= "world" (str 'world))
"You can do more than create strings, you can put them together" "You can do more than create strings, you can put them together"
(= "Cool right?" (str __ __)) (= "Cool right?" (str "Cool right?"))
"You can even get certain characters" "You can even get certain characters"
(= \C (get "Characters" __)) (= \C (get "Characters" 0))
"Or even count the characters" "Or even count the characters"
(= __ (count "Hello World")) (= 11 (count "Hello World"))
"But strings and characters are not the same" "But strings and characters are not the same"
(= __ (= \c "c")) (= false (= \c "c"))
"What if you only wanted to get part of a string?" "What if you only wanted to get part of a string?"
(= "World" (subs "Hello World" __ __)) (= "World" (subs "Hello World" 6 11))
"How about joining together elements in a list?" "How about joining together elements in a list?"
(= __ (string/join '(1 2 3))) (= "123" (string/join '(1 2 3)))
"What if you wanted to separate them out?" "What if you wanted to separate them out?"
(= "1, 2, 3" (string/join __ '(1 2 3))) (= "1, 2, 3" (string/join ", " '(1 2 3)))
"Maybe you want to separate out all your lines" "Maybe you want to separate out all your lines"
(= [__ __ __] (string/split-lines "1\n2\n3")) (= ["1", "2", "3"] (string/split-lines "1\n2\n3"))
"You may want to make sure your words are backwards" "You may want to make sure your words are backwards"
(= __ (string/reverse "hello")) (= "olleh" (string/reverse "hello"))
"Maybe you want to find the index of the first occurence of a substring" "Maybe you want to find the index of the first occurence of a substring"
(= 0 (string/index-of "hello world" __)) (= 0 (string/index-of "hello world" "h"))
"Or maybe the last index of the same" "Or maybe the last index of the same"
(= __ (string/last-index-of "hello world, hello" "hello")) (= 13 (string/last-index-of "hello world, hello" "hello"))
"But when something doesn't exist, nothing is found" "But when something doesn't exist, nothing is found"
(= __ (string/index-of "hello world" "bob")) (= nil (string/index-of "hello world" "bob"))
"Sometimes you don't want whitespace cluttering the front and back" "Sometimes you don't want whitespace cluttering the front and back"
(= __ (string/trim " \nhello world \t \n")) (= "hello world" (string/trim " \nhello world \t \n"))
"You can check if something is a char" "You can check if something is a char"
(= __ (char? \c)) (= true (char? \c))
"But it may not be" "But it may not be"
(= __ (char? "a")) (= false (char? "a"))
"But chars aren't strings" "But chars aren't strings"
(= __ (string? \b)) (= false (string? \b))
"Strings are strings" "Strings are strings"
(= true (string? __)) (= true (string? "string"))
"Some strings may be blank" "Some strings may be blank"
(= __ (string/blank? "")) (= true (string/blank? ""))
"Even if at first glance they aren't" "Even if at first glance they aren't"
(= __ (string/blank? " \n \t ")) (= true (string/blank? " \n \t "))
"However, most strings aren't blank" "However, most strings aren't blank"
(= __ (string/blank? "hello?\nare you out there?"))) (= false (string/blank? "hello?\nare you out there?")))

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@ -3,43 +3,43 @@
(meditations (meditations
"Lists can be expressed by function or a quoted form" "Lists can be expressed by function or a quoted form"
(= '(__ __ __ __ __) (list 1 2 3 4 5)) (= '(1 2 3 4 5) (list 1 2 3 4 5))
"They are Clojure seqs (sequences), so they allow access to the first" "They are Clojure seqs (sequences), so they allow access to the first"
(= __ (first '(1 2 3 4 5))) (= 1 (first '(1 2 3 4 5)))
"As well as the rest" "As well as the rest"
(= __ (rest '(1 2 3 4 5))) (= '(2 3 4 5) (rest '(1 2 3 4 5)))
"Count your blessings" "Count your blessings"
(= __ (count '(dracula dooku chocula))) (= 3 (count '(dracula dooku chocula)))
"Before they are gone" "Before they are gone"
(= __ (count '())) (= 0 (count '()))
"The rest, when nothing is left, is empty" "The rest, when nothing is left, is empty"
(= __ (rest '(100))) (= () (rest '(100)))
"Construction by adding an element to the front is easy" "Construction by adding an element to the front is easy"
(= __ (cons :a '(:b :c :d :e))) (= '(:a :b :c :d :e) (cons :a '(:b :c :d :e)))
"Conjoining an element to a list isn't hard either" "Conjoining an element to a list isn't hard either"
(= __ (conj '(:a :b :c :d) :e)) (= '(:e :a :b :c :d) (conj '(:a :b :c :d) :e))
"You can use a list like a stack to get the first element" "You can use a list like a stack to get the first element"
(= __ (peek '(:a :b :c :d :e))) (= :a (peek '(:a :b :c :d :e)))
"Or the others" "Or the others"
(= __ (pop '(:a :b :c :d :e))) (= '(:b :c :d :e) (pop '(:a :b :c :d :e)))
"But watch out if you try to pop nothing" "But watch out if you try to pop nothing"
(= __ (try (= "No dice!" (try
(pop '()) (pop '())
(catch IllegalStateException e (catch IllegalStateException e
"No dice!"))) "No dice!")))
"The rest of nothing isn't so strict" "The rest of nothing isn't so strict"
(= __ (try (= '() (try
(rest '()) (rest '())
(catch IllegalStateException e (catch IllegalStateException e
"No dice!")))) "No dice!"))))

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@ -3,31 +3,31 @@
(meditations (meditations
"You can use vectors in clojure as array-like structures" "You can use vectors in clojure as array-like structures"
(= __ (count [42])) (= 1 (count [42]))
"You can create a vector from a list" "You can create a vector from a list"
(= __ (vec '(1))) (= [1] (vec '(1)))
"Or from some elements" "Or from some elements"
(= __ (vector nil nil)) (= [nil, nil] (vector nil nil))
"But you can populate it with any number of elements at once" "But you can populate it with any number of elements at once"
(= [1 __] (vec '(1 2))) (= [1, 2] (vec '(1 2)))
"Conjoining to a vector is different than to a list" "Conjoining to a vector is different than to a list"
(= __ (conj [111 222] 333)) (= [111, 222, 333] (conj [111 222] 333))
"You can get the first element of a vector like so" "You can get the first element of a vector like so"
(= __ (first [:peanut :butter :and :jelly])) (= :peanut (first [:peanut :butter :and :jelly]))
"And the last in a similar fashion" "And the last in a similar fashion"
(= __ (last [:peanut :butter :and :jelly])) (= :jelly (last [:peanut :butter :and :jelly]))
"Or any index if you wish" "Or any index if you wish"
(= __ (nth [:peanut :butter :and :jelly] 3)) (= :jelly (nth [:peanut :butter :and :jelly] 3))
"You can also slice a vector" "You can also slice a vector"
(= __ (subvec [:peanut :butter :and :jelly] 1 3)) (= [:butter, :and] (subvec [:peanut :butter :and :jelly] 1 3))
"Equality with collections is in terms of values" "Equality with collections is in terms of values"
(= (list 1 2 3) (vector 1 2 __))) (= (list 1 2 3) (vector 1 2 3)))

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(meditations (meditations
"You can create a set by converting another collection" "You can create a set by converting another collection"
(= #{3} (set __)) (= #{3} (set #{3}))
"Counting them is like counting other collections" "Counting them is like counting other collections"
(= __ (count #{1 2 3})) (= 3 (count #{1 2 3}))
"Remember that a set is a *mathematical* set" "Remember that a set is a *mathematical* set"
(= __ (set '(1 1 2 2 3 3 4 4 5 5))) (= #{1 2 3 4 5} (set '(1 1 2 2 3 3 4 4 5 5)))
"You can ask clojure for the union of two sets" "You can ask clojure for the union of two sets"
(= __ (set/union #{1 2 3 4} #{2 3 5})) (= #{1 2 3 4 5} (set/union #{1 2 3 4} #{2 3 5}))
"And also the intersection" "And also the intersection"
(= __ (set/intersection #{1 2 3 4} #{2 3 5})) (= #{2, 3} (set/intersection #{1 2 3 4} #{2 3 5}))
"But don't forget about the difference" "But don't forget about the difference"
(= __ (set/difference #{1 2 3 4 5} #{2 3 5}))) (= #{1 4} (set/difference #{1 2 3 4 5} #{2 3 5})))

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@ -3,48 +3,48 @@
(meditations (meditations
"Don't get lost when creating a map" "Don't get lost when creating a map"
(= {:a 1 :b 2} (hash-map :a 1 __ __)) (= {:a 1 :b 2} (hash-map :a 1 :b 2))
"A value must be supplied for each key" "A value must be supplied for each key"
(= {:a 1} (hash-map :a __)) (= {:a 1} (hash-map :a 1))
"The size is the number of entries" "The size is the number of entries"
(= __ (count {:a 1 :b 2})) (= 2 (count {:a 1 :b 2}))
"You can look up the value for a given key" "You can look up the value for a given key"
(= __ (get {:a 1 :b 2} :b)) (= 2 (get {:a 1 :b 2} :b))
"Maps can be used as functions to do lookups" "Maps can be used as functions to do lookups"
(= __ ({:a 1 :b 2} :a)) (= 1 ({:a 1 :b 2} :a))
"And so can keywords" "And so can keywords"
(= __ (:a {:a 1 :b 2})) (= 1 (:a {:a 1 :b 2}))
"But map keys need not be keywords" "But map keys need not be keywords"
(= __ ({2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"} 2014)) (= "Sochi" ({2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"} 2014))
"You may not be able to find an entry for a key" "You may not be able to find an entry for a key"
(= __ (get {:a 1 :b 2} :c)) (= nil (get {:a 1 :b 2} :c))
"But you can provide your own default" "But you can provide your own default"
(= __ (get {:a 1 :b 2} :c :key-not-found)) (= :key-not-found (get {:a 1 :b 2} :c :key-not-found))
"You can find out if a key is present" "You can find out if a key is present"
(= __ (contains? {:a nil :b nil} :b)) (= true (contains? {:a nil :b nil} :b))
"Or if it is missing" "Or if it is missing"
(= __ (contains? {:a nil :b nil} :c)) (= false (contains? {:a nil :b nil} :c))
"Maps are immutable, but you can create a new and improved version" "Maps are immutable, but you can create a new and improved version"
(= {1 "January" 2 __} (assoc {1 "January"} 2 "February")) (= {1 "January" 2 "February"} (assoc {1 "January"} 2 "February"))
"You can also create a new version with an entry removed" "You can also create a new version with an entry removed"
(= {__ __} (dissoc {1 "January" 2 "February"} 2)) (= {1 "January"} (dissoc {1 "January" 2 "February"} 2))
"Often you will need to get the keys, but the order is undependable" "Often you will need to get the keys, but the order is undependable"
(= (list __ __ __) (= (list 2010 2014 2018)
(sort (keys { 2014 "Sochi" 2018 "PyeongChang" 2010 "Vancouver"}))) (sort (keys { 2014 "Sochi" 2018 "PyeongChang" 2010 "Vancouver"})))
"You can get the values in a similar way" "You can get the values in a similar way"
(= (list __ __ __) (= (list "PyeongChang" "Sochi" "Vancouver")
(sort (vals {2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"})))) (sort (vals {2010 "Vancouver" 2014 "Sochi" 2018 "PyeongChang"}))))

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(meditations (meditations
"Calling a function is like giving it a hug with parentheses" "Calling a function is like giving it a hug with parentheses"
(= __ (square 9)) (= 81 (square 9))
"Functions are usually defined before they are used" "Functions are usually defined before they are used"
(= __ (multiply-by-ten 2)) (= 20 (multiply-by-ten 2))
"But they can also be defined inline" "But they can also be defined inline"
(= __ ((fn [n] (* 5 n)) 2)) (= 10 ((fn [n] (* 5 n)) 2))
"Or using an even shorter syntax" "Or using an even shorter syntax"
(= __ (#(* 15 %) 4)) (= 60 (#(* 15 %) 4))
"Even anonymous functions may take multiple arguments" "Even anonymous functions may take multiple arguments"
(= __ (#(+ %1 %2 %3) 4 5 6)) (= 15 (#(+ %1 %2 %3) 4 5 6))
"Arguments can also be skipped" "Arguments can also be skipped"
(= __ (#(* 15 %2) 1 2)) (= 30 (#(* 15 %2) 1 2))
"One function can beget another" "One function can beget another"
(= 9 (((fn [] ___)) 4 5)) (= 9 ((#(fn [a b] (+ a b))) 4 5))
"Functions can also take other functions as input" "Functions can also take other functions as input"
(= 20 ((fn [f] (f 4 5)) (= 20 ((fn [f] (f 4 5))
___)) *))
"Higher-order functions take function arguments" "Higher-order functions take function arguments"
(= 25 (___ (= 25 ((fn [aFun] (aFun 5))
(fn [n] (* n n)))) (fn [n] (* n n))))
"But they are often better written using the names of functions" "But they are often better written using the names of functions"
(= 25 (___ square))) (= 25 ((fn [squre] (squre 5)) square)))