Merge ead7f24c06 into b31227c0a8
This commit is contained in:
commit
b6ecd8a6ec
7 changed files with 86 additions and 86 deletions
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@ -3,37 +3,37 @@
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(meditations
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(meditations
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"We shall contemplate truth by testing reality, via equality"
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"We shall contemplate truth by testing reality, via equality"
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(= __ true)
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(= true true)
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"To understand reality, we must compare our expectations against reality"
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"To understand reality, we must compare our expectations against reality"
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(= __ (+ 1 1))
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(= 2 (+ 1 1))
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"You can test equality of many things"
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"You can test equality of many things"
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(= (+ 3 4) 7 (+ 2 __))
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(= (+ 3 4) 7 (+ 2 5))
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"Some things may appear different, but be the same"
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"Some things may appear different, but be the same"
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(= __ (= 2 2/1))
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(= true (= 2 2/1))
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"You cannot generally float to heavens of integers"
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"You cannot generally float to heavens of integers"
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(= __ (= 2 2.0))
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(= false (= 2 2.0))
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"But a looser equality is also possible"
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"But a looser equality is also possible"
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(= __ (== 2.0 2))
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(= true (== 2.0 2))
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"Something is not equal to nothing"
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"Something is not equal to nothing"
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(= __ (not (= 1 nil)))
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(= true (not (= 1 nil)))
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"Strings, and keywords, and symbols: oh my!"
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"Strings, and keywords, and symbols: oh my!"
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(= __ (= "hello" :hello 'hello))
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(= false (= "hello" :hello 'hello))
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"Make a keyword with your keyboard"
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"Make a keyword with your keyboard"
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(= :hello (keyword __))
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(= :hello (keyword "hello"))
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"Symbolism is all around us"
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"Symbolism is all around us"
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(= 'hello (symbol __))
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(= 'hello (symbol "hello"))
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"What could be equivalent to nothing?"
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"What could be equivalent to nothing?"
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(= __ nil)
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(= __ nil)
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"When things cannot be equal, they must be different"
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"When things cannot be equal, they must be different"
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(not= :fill-in-the-blank __))
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(not= :fill-in-the-blank :not-equal))
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@ -4,67 +4,67 @@
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(meditations
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(meditations
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"A string is nothing more than text surrounded by double quotes"
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"A string is nothing more than text surrounded by double quotes"
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(= __ "hello")
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(= "hello" "hello")
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"But double quotes are just magic on top of something deeper"
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"But double quotes are just magic on top of something deeper"
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(= __ (str 'world))
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(= "world" (str 'world))
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"You can do more than create strings, you can put them together"
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"You can do more than create strings, you can put them together"
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(= "Cool right?" (str __ __))
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(= "Cool right?" (str "Cool right?"))
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"You can even get certain characters"
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"You can even get certain characters"
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(= \C (get "Characters" __))
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(= \C (get "Characters" 0))
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"Or even count the characters"
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"Or even count the characters"
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(= __ (count "Hello World"))
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(= 11 (count "Hello World"))
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"But strings and characters are not the same"
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"But strings and characters are not the same"
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(= __ (= \c "c"))
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(= false (= \c "c"))
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"What if you only wanted to get part of a string?"
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"What if you only wanted to get part of a string?"
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(= "World" (subs "Hello World" __ __))
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(= "World" (subs "Hello World" 6 11))
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"How about joining together elements in a list?"
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"How about joining together elements in a list?"
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(= __ (string/join '(1 2 3)))
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(= "123" (string/join '(1 2 3)))
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"What if you wanted to separate them out?"
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"What if you wanted to separate them out?"
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(= "1, 2, 3" (string/join __ '(1 2 3)))
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(= "1, 2, 3" (string/join ", " '(1 2 3)))
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"Maybe you want to separate out all your lines"
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"Maybe you want to separate out all your lines"
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(= [__ __ __] (string/split-lines "1\n2\n3"))
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(= ["1", "2", "3"] (string/split-lines "1\n2\n3"))
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"You may want to make sure your words are backwards"
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"You may want to make sure your words are backwards"
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(= __ (string/reverse "hello"))
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(= "olleh" (string/reverse "hello"))
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"Maybe you want to find the index of the first occurence of a substring"
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"Maybe you want to find the index of the first occurence of a substring"
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(= 0 (string/index-of "hello world" __))
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(= 0 (string/index-of "hello world" "h"))
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"Or maybe the last index of the same"
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"Or maybe the last index of the same"
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(= __ (string/last-index-of "hello world, hello" "hello"))
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(= 13 (string/last-index-of "hello world, hello" "hello"))
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"But when something doesn't exist, nothing is found"
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"But when something doesn't exist, nothing is found"
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(= __ (string/index-of "hello world" "bob"))
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(= nil (string/index-of "hello world" "bob"))
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"Sometimes you don't want whitespace cluttering the front and back"
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"Sometimes you don't want whitespace cluttering the front and back"
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(= __ (string/trim " \nhello world \t \n"))
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(= "hello world" (string/trim " \nhello world \t \n"))
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"You can check if something is a char"
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"You can check if something is a char"
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(= __ (char? \c))
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(= true (char? \c))
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"But it may not be"
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"But it may not be"
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(= __ (char? "a"))
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(= false (char? "a"))
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"But chars aren't strings"
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"But chars aren't strings"
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(= __ (string? \b))
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(= false (string? \b))
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"Strings are strings"
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"Strings are strings"
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(= true (string? __))
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(= true (string? "string"))
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"Some strings may be blank"
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"Some strings may be blank"
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(= __ (string/blank? ""))
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(= true (string/blank? ""))
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"Even if at first glance they aren't"
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"Even if at first glance they aren't"
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(= __ (string/blank? " \n \t "))
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(= true (string/blank? " \n \t "))
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"However, most strings aren't blank"
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"However, most strings aren't blank"
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(= __ (string/blank? "hello?\nare you out there?")))
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(= false (string/blank? "hello?\nare you out there?")))
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@ -3,43 +3,43 @@
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(meditations
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(meditations
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"Lists can be expressed by function or a quoted form"
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"Lists can be expressed by function or a quoted form"
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(= '(__ __ __ __ __) (list 1 2 3 4 5))
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(= '(1 2 3 4 5) (list 1 2 3 4 5))
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"They are Clojure seqs (sequences), so they allow access to the first"
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"They are Clojure seqs (sequences), so they allow access to the first"
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(= __ (first '(1 2 3 4 5)))
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(= 1 (first '(1 2 3 4 5)))
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"As well as the rest"
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"As well as the rest"
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(= __ (rest '(1 2 3 4 5)))
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(= '(2 3 4 5) (rest '(1 2 3 4 5)))
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"Count your blessings"
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"Count your blessings"
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(= __ (count '(dracula dooku chocula)))
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(= 3 (count '(dracula dooku chocula)))
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"Before they are gone"
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"Before they are gone"
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(= __ (count '()))
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(= 0 (count '()))
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"The rest, when nothing is left, is empty"
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"The rest, when nothing is left, is empty"
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(= __ (rest '(100)))
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(= () (rest '(100)))
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"Construction by adding an element to the front is easy"
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"Construction by adding an element to the front is easy"
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(= __ (cons :a '(:b :c :d :e)))
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(= '(:a :b :c :d :e) (cons :a '(:b :c :d :e)))
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"Conjoining an element to a list isn't hard either"
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"Conjoining an element to a list isn't hard either"
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(= __ (conj '(:a :b :c :d) :e))
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(= '(:e :a :b :c :d) (conj '(:a :b :c :d) :e))
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"You can use a list like a stack to get the first element"
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"You can use a list like a stack to get the first element"
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(= __ (peek '(:a :b :c :d :e)))
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(= :a (peek '(:a :b :c :d :e)))
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"Or the others"
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"Or the others"
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(= __ (pop '(:a :b :c :d :e)))
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(= '(:b :c :d :e) (pop '(:a :b :c :d :e)))
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"But watch out if you try to pop nothing"
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"But watch out if you try to pop nothing"
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(= __ (try
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(= "No dice!" (try
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(pop '())
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(pop '())
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(catch IllegalStateException e
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(catch IllegalStateException e
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"No dice!")))
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"No dice!")))
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"The rest of nothing isn't so strict"
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"The rest of nothing isn't so strict"
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(= __ (try
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(= '() (try
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(rest '())
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(rest '())
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(catch IllegalStateException e
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(catch IllegalStateException e
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"No dice!"))))
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"No dice!"))))
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@ -3,31 +3,31 @@
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(meditations
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(meditations
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||||||
"You can use vectors in clojure as array-like structures"
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"You can use vectors in clojure as array-like structures"
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(= __ (count [42]))
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(= 1 (count [42]))
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"You can create a vector from a list"
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"You can create a vector from a list"
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(= __ (vec '(1)))
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(= [1] (vec '(1)))
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||||||
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"Or from some elements"
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"Or from some elements"
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(= __ (vector nil nil))
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(= [nil, nil] (vector nil nil))
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||||||
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"But you can populate it with any number of elements at once"
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"But you can populate it with any number of elements at once"
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(= [1 __] (vec '(1 2)))
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(= [1, 2] (vec '(1 2)))
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"Conjoining to a vector is different than to a list"
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"Conjoining to a vector is different than to a list"
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(= __ (conj [111 222] 333))
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(= [111, 222, 333] (conj [111 222] 333))
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"You can get the first element of a vector like so"
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"You can get the first element of a vector like so"
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(= __ (first [:peanut :butter :and :jelly]))
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(= :peanut (first [:peanut :butter :and :jelly]))
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"And the last in a similar fashion"
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"And the last in a similar fashion"
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(= __ (last [:peanut :butter :and :jelly]))
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(= :jelly (last [:peanut :butter :and :jelly]))
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"Or any index if you wish"
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"Or any index if you wish"
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(= __ (nth [:peanut :butter :and :jelly] 3))
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(= :jelly (nth [:peanut :butter :and :jelly] 3))
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"You can also slice a vector"
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"You can also slice a vector"
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(= __ (subvec [:peanut :butter :and :jelly] 1 3))
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(= [:butter, :and] (subvec [:peanut :butter :and :jelly] 1 3))
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"Equality with collections is in terms of values"
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"Equality with collections is in terms of values"
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(= (list 1 2 3) (vector 1 2 __)))
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(= (list 1 2 3) (vector 1 2 3)))
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@ -4,19 +4,19 @@
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(meditations
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(meditations
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||||||
"You can create a set by converting another collection"
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"You can create a set by converting another collection"
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(= #{3} (set __))
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(= #{3} (set #{3}))
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"Counting them is like counting other collections"
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"Counting them is like counting other collections"
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(= __ (count #{1 2 3}))
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(= 3 (count #{1 2 3}))
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"Remember that a set is a *mathematical* set"
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"Remember that a set is a *mathematical* set"
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(= __ (set '(1 1 2 2 3 3 4 4 5 5)))
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(= #{1 2 3 4 5} (set '(1 1 2 2 3 3 4 4 5 5)))
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"You can ask clojure for the union of two sets"
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"You can ask clojure for the union of two sets"
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(= __ (set/union #{1 2 3 4} #{2 3 5}))
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(= #{1 2 3 4 5} (set/union #{1 2 3 4} #{2 3 5}))
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||||||
"And also the intersection"
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"And also the intersection"
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(= __ (set/intersection #{1 2 3 4} #{2 3 5}))
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(= #{2, 3} (set/intersection #{1 2 3 4} #{2 3 5}))
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||||||
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||||||
"But don't forget about the difference"
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"But don't forget about the difference"
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(= __ (set/difference #{1 2 3 4 5} #{2 3 5})))
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(= #{1 4} (set/difference #{1 2 3 4 5} #{2 3 5})))
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@ -3,48 +3,48 @@
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(meditations
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(meditations
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||||||
"Don't get lost when creating a map"
|
"Don't get lost when creating a map"
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||||||
(= {:a 1 :b 2} (hash-map :a 1 __ __))
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(= {:a 1 :b 2} (hash-map :a 1 :b 2))
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||||||
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||||||
"A value must be supplied for each key"
|
"A value must be supplied for each key"
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||||||
(= {:a 1} (hash-map :a __))
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(= {:a 1} (hash-map :a 1))
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||||||
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||||||
"The size is the number of entries"
|
"The size is the number of entries"
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||||||
(= __ (count {:a 1 :b 2}))
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(= 2 (count {:a 1 :b 2}))
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||||||
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|
||||||
"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))
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(= 2 (get {:a 1 :b 2} :b))
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||||||
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|
||||||
"Maps can be used as functions to do lookups"
|
"Maps can be used as functions to do lookups"
|
||||||
(= __ ({:a 1 :b 2} :a))
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(= 1 ({:a 1 :b 2} :a))
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||||||
|
|
||||||
"And so can keywords"
|
"And so can keywords"
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||||||
(= __ (: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"))
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||||||
|
|
||||||
"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"}))))
|
||||||
|
|
|
||||||
|
|
@ -8,33 +8,33 @@
|
||||||
|
|
||||||
(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)))
|
||||||
|
|
|
||||||
Loading…
Reference in a new issue