Community documentation for Janet

(string/bytes "hello") # => (104 101 108 108 111)

(get      [4 5 6]   -1     )  # => nil
(in       [4 5 6]   -1  42 )  # error
(get-in   [4 5 6]  [-1] 42 )  # => 42

(get     {:a 1}   -1     )  # => nil
(in      {:a 1}   -1  42 )  # => 42
(get-in  {:a 1}  [-1] 42 )  # => 42

(update-in @{:a 1} [:a] (fn [x] (+ 1 x)))
# @{:a 2}

(map nil? [nil  0     false []   ])
# =>     @[true false false false]

(seq [v :in (coro
                (yield :hi)
                (yield :bye))]
    v)
# => @[:hi :bye]

(string "hello " "world") # => "hello world"

(os/execute
  ["python" "-c" "print('Hello Janet'"])
  :p

(def [stdin-r stdin-w] (os/pipe))
(def [stdout-r stdout-w] (os/pipe))

# write the input that will be sent to sed
(:write stdin-w "hello world 1\nhello world 2")
(:close stdin-w)

(os/execute
  ["sed" "s|world|janet|g"]
  :px
  # the program reads from :in and writes to :out
  {:in stdin-r :out stdout-w})

(:read stdout-r math/int32-max)
# => @"hello janet 1\nhello janet 2"

# feed two lines to sed, which replaces "world"
# with "janet", and read the modified results back

(drop-until |(> $ 8)
            [1 1 2 3 4 5 8 13 21])
# => '(13 21)

(invert [(chr "y") (chr "o")])
# => @{111 1 121 0}

(math/round 1.1)  # => 1
(map math/round [1.49 1.50 1.51])  # => @[1 2 2]

# janet 1.10.1

(all pos? [1 2 3])     # => true
(all pos? [1 2 3 -4])  # => false
(all pos? [1 2 3 0])   # => false

(all (partial string/has-prefix? "a") ["aa" "ab"])       # => true
(all (partial string/has-prefix? "a") ["aa" "ab" "bb"])  # => false

(all truthy? [1 2])              # => true
(all truthy? [1 2 3])            # => true
(all truthy? [1 2 nil 3])        # => false
(all truthy? [1 false 2 nil 3])  # => false

(all (fn [x] x) [1 2])              # => 2
(all (fn [x] x) [1 2 3])            # => 3
(all (fn [x] x) [1 2 nil 3])        # => nil
(all (fn [x] x) [1 false 2 nil 3])  # => false

(peg/find ':a "Battery temperature: 40 °C")

# => 0 index of the first upper/lower case character

# :a (range "az" "AZ")

(ev/spawn (os/sleep 1) (print "Hard work is done!"))

# prints "Hard work is done!" after one second
# this is the easiest way to put some forms on the event loop
# but do not forget REPL is blocking, for now, so run the example with `janet -e`

(def [pipe-r pipe-w] (os/pipe))
(:write pipe-w "hello")
(:read pipe-r 5)
# => @"hello"

# send the string "hello" into the writable stream
# part and read it back from the readable one