读取 Clojure 字符

(1 "two" 3.0)

user=> (get ["a" 13.7 :foo] 1)
13.7

user=> (keys {:a 1 :b 2})
(:a :b)

user=> #{1 2 3 4}
#{1 2 3 4}
user=> (hash-set 1 2 3 4)
#{1 2 3 4}

user=> #{1 2 3 4 1}
Syntax error reading source at (REPL:83:13).
Duplicate key: 1

user=> [1 2 3 #_ 4 5]
[1 2 3 5]

user=> [1 2 3 #_4 5]
[1 2 3 5]

user=> {:a 1, #_#_ :b 2, :c 3}
{:a 1, :c 3}

user=> (re-matches #"^test$" "test")
"test"

; anonymous function taking a single argument and printing it
(fn [line] (println line))

; anonymous function taking a single argument and printing it - shorthand
#(println %)

user=> (macroexpand `#(println %))
(fn* [arg] (clojure.core/println arg)) ; argument names shortened for clarity

user=> (read-string "#'foo")
(var foo)
user=> (def nine 9)
#'user/nine
user=> nine
9
user=> (var nine)
#'user/nine
user=> #'nine
#'user/nine

user=> (/ 1.0 0.0)
##Inf
user=> (/ -1.0 0.0)
##-Inf
user=> (Math/sqrt -1.0)
##NaN

user=> (type #inst "2014-05-19T19:12:37.925-00:00")
java.util.Date ;; this is host dependent
user=> (read-string "#inst \"2014-05-19T19:12:37.925-00:00\"")
#inst "2014-05-19T19:12:37.925-00:00"

user=> (macroexpand `#(println %))
(fn* [arg1] (clojure.core/println arg1))

user=> (#(println %1 %2) "Hello " "Clojure")
Hello Clojure ; takes 2 args
user=> (macroexpand `#(println %1 %2))
(fn* [arg1 arg2] (clojure.core/println arg1 arg2)) ; takes 2 args

user=> (#(println %4) "Hello " "Clojure " ", Thank " "You!!")
You!! ; takes 4 args, doesn't use first 3 args
user=> (macroexpand `#(println %4))
(fn* [arg1 arg2 arg3 arg4] (clojure.core/println arg4)) ; takes 4 args doesn't use 3

user=> (macroexpand `#(println % %1)) ; use both % and %1
(fn* [arg1] (clojure.core/println arg1 arg1)) ; still only takes 1 argument

user=> (#(println %&) "Hello " "Clojure " ", Thank " "You!!")
(Hello Clojure , Thank You!! ) ; takes n args
user=> (macroexpand '#(println %&))
(fn* [& rest__11#] (println rest__11#))

user=> (def x (atom 1))
#'user/x
user=> @x
1
user=> (deref x)
1
user=>

user=> (def ^{:debug true} five 5) ; meta map with single boolean value
#'user/five

user=> (def ^{:debug true} five 5)
#'user/five
user=> (meta #'five)
{:ns #<Namespace user>, :name five, :column 1, :debug true, :line 1, :file "NO_SOURCE_PATH"}

user=> (def ^:debug five 5)
#'user/five
user=> (meta #'five)
{:ns #<Namespace user>, :name five, :column 1, :debug true, :line 1, :file "NO_SOURCE_PATH"}

user=> (def ^Integer five 5)
#'user/five
user=> (meta #'five)
{:ns #<Namespace user>, :name five, :column 1, :line 1, :file "NO_SOURCE_PATH", :tag java.lang.Integer}

user=> (def ^Integer ^:debug ^:private five 5)
#'user/five
user=> (meta #'five)
{:ns #<Namespace user>, :name five, :column 1, :private true, :debug true, :line 1, :file "NO_SOURCE_PATH", :tag java.lang.Integer}

user=> (1 3 4) ; fails as it tries to invoke 1 as a function

Execution error (ClassCastException) at myproject.person-names/eval230 (REPL:1).
class java.lang.Long cannot be cast to class clojure.lang.IFn

user=> '(1 3 4) ; quote
(1 3 4)

user=> (quote (1 2 3)) ; using the longer quote method
(1 2 3)
user=>

user=> (def x "x") ; this is a comment
#'user/x
user=> ; this is a comment too
<returns nothing>

;; This is probably more important than

; this

user=> (type :test)
clojure.lang.Keyword

user=> (keyword "test")
:test

user=> (def my-map {:one 1 :two 2})
#'user/my-map
user=> (:one my-map) ; get the value for :one by invoking it as function
1
user=> (:three my-map) ; it can safely check for missing keys
nil
user=> (:three my-map 3) ; it can return a default if specified
3
user => (get my-map :three 3) ; same as above, but using get
3

user=> :my-keyword
:my-keyword
user=> ::my-keyword
:user/my-keyword
user=> (= ::my-keyword :my-keyword)
false

#:person{:first "Han"
         :last "Solo"
         :ship #:ship{:name "Millennium Falcon"
                      :model "YT-1300f light freighter"}}

{:person/first "Han"
 :person/last "Solo"
 :person/ship {:ship/name "Millennium Falcon"
               :ship/model "YT-1300f light freighter"}}

user=> (keys {:user/a 1, :user/b 2})
(:user/a :user/b)
user=> (keys #::{:a 1, :b 2})
(:user/a :user/b)

(ns rebel.core
  (:require
    [rebel.person :as p]
    [rebel.ship   :as s] ))

#::p{:first "Han"
     :last "Solo"
     :ship #::s{:name "Millennium Falcon"
                :model "YT-1300f light freighter"}}

{:rebel.person/first "Han"
 :rebel.person/last "Solo"
 :rebel.person/ship {:rebel.ship/name "Millennium Falcon"
                     :rebel.ship/model "YT-1300f light freighter"}}

user=> (str \h \i)
"hi"

(import (basex.core BaseXClient$EventNotifier)

(defn- build-notifier [notifier-action]
  (reify BaseXClient$EventNotifier
    (notify [this value]
      (notifier-action value))))

user=> (1 2 3)
Execution error (ClassCastException) at myproject.person-names/eval232 (REPL:1).
class java.lang.Long cannot be cast to class clojure.lang.IFn
user=> `(1 2 3)
(1 2 3)

user=> (def five 5)
#'user/five
user=> `five
user/five

user=> (defmacro debug [body]
  #_=>   `(let [val# ~body]
  #_=>      (println "DEBUG: " val#)
  #_=>      val#))
#'user/debug
user=> (debug (+ 2 2))
DEBUG:  4
4

user=> (def five 5) ; create a named var with the value 5
#'user/five
user=> five ; the symbol five is evaluated to its value
5
user=> `five ; syntax quoting five will avoid evaluating the symbol, and fully resolve it
user/five
user=> `~five ; within a syntax quoted block, ~ will turn evaluation back on just for the next form
5
user=> `[inc ~(+ 1 five)]
[clojure.core/inc 6]

user=> (def three-and-four (list 3 4))
#'user/three-and-four
user=> `(1 ~three-and-four) ; evaluates `three-and-four` and places it in the result
(1 (3 4))
user=> `(1 ~@three-and-four) ;  evaluates `three-and-four` and places its contents in the result
(1 3 4)

user=> (defmacro m [] `(let [x 1] x))
#'user/m
user=> (m)
Syntax error macroexpanding clojure.core/let at (REPL:1:1).
myproject.person-names/x - failed: simple-symbol? at: [:bindings :form :local-symbol]
  spec: :clojure.core.specs.alpha/local-name
myproject.person-names/x - failed: vector? at: [:bindings :form :seq-destructure]
  spec: :clojure.core.specs.alpha/seq-binding-form
myproject.person-names/x - failed: map? at: [:bindings :form :map-destructure]
  spec: :clojure.core.specs.alpha/map-bindings
myproject.person-names/x - failed: map? at: [:bindings :form :map-destructure]
  spec: :clojure.core.specs.alpha/map-special-binding

user=> (defmacro m [] `(let [x# 1] x#))
#'user/m
user=> (m)
1
user=>

user=> (macroexpand '(m))
(let* [x__681__auto__ 1] x__681__auto__)

#?(:clj  (Clojure expression)
   :cljs (ClojureScript expression)
   :cljr (Clojure CLR expression)
   :default (fallthrough expression))

(defn build-list []
  (list #?@(:clj  [5 6 7 8]
            :cljs [1 2 3 4])))

(defn build-list []
  (list 5 6 7 8))

user=> (def my-channel (chan 10)) ; create a channel
user=> (>!! my-channel "hello")   ; put stuff on the channel
user=> (println (<!! my-channel)) ; take stuff off the channel
hello

user=> (def c (chan))
#'user/c
user=> (>! c "nope")
AssertionError Assert failed: >! used not in (go ...) block
nil  clojure.core.async/>! (async.clj:123)

(def my-buffer (buffers/create-buffer [1 2 3]))
(buffers/empty my-buffer)

(def my-buffer (buffers/create-buffer [1 2 3]))
(buffers/empty? my-buffer)
false

user=> (def my-stateful-thing (atom 0))
#'user/my-stateful-thing
user=> (swap! my-stateful-thing inc)
1
user=> @my-stateful-thing
1

(def value (atom 0))

(add-watch value nil (fn [_ _ _ new-value]
                       (println new-value))

(reset! value 6)
; prints 6
(reset! value 9)
; prints 9

user=>(def m {:a 1, :b 2, :c 3}
{:a 1, :b 2, :c 3}