Community documentation for Janet

(comment this is a
         multiline line comment.
         It won't do anything)

(map indexed?    [ 'ab   :ab   "ab"   @"ab"  [97 98]  @[97 98]  {0 97 1 98}  @{0 97 1 98}  ])
# =>            @[ false false false  false  true     true      false        false         ]

(map tuple?      [ 'ab   :ab   "ab"   @"ab"  [97 98]  @[97 98]  {0 97 1 98}  @{0 97 1 98}  ])
# =>            @[ false false false  false  true     false     false        false         ]

(map array?      [ 'ab   :ab   "ab"   @"ab"  [97 98]  @[97 98]  {0 97 1 98}  @{0 97 1 98}  ])
# =>            @[ false false false  false  false    true      false        false         ]

(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

# Print out the current time in Last-Modified header-compliant 
# form. (reference: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Last-Modified)
(def weekdayMap [ "Sun" "Mon" "Tue" "Wed" "Thu" "Fri" "Sat" ])
(def monthMap ["Jan" "Feb" "Mar" "Apr" "May" "Jun" "Jul" "Aug" "Sep" "Oct" "Nov" "Dec"])
(def dt (os/date (os/time) true))
(string/format "%s, %02d %s %04d %02d:%02d:%02d" 
     (weekdayMap (dt :week-day)) 
     (dt :month-day)
     (monthMap (dt :month))
     (dt :year)
     (dt :hours)
     (dt :minutes)
     (dt :seconds))

(->> (range 10) (map (fn [arg] (* arg arg))))

# => @[0 1 4 9 16 25 36 49 64 81]

(buffer/bit-set @"hahaha" 3) # => @"hahaha"

(buffer/bit-set @"what" 3) # => @"\x7Fhat"

(net/address "0.0.0.0" 80) # => <core/socket-address 0x55CABA438E90>

(net/address "0.0.0.0" 8989) # => <core/socket-address 0x55CABA439980>

(type (fiber/new (fn [])))
# =>
:fiber

(apply * [1 2 3])     # -> 6
(* (splice [1 2 3]))  # -> 6
(* ;[1 2 3])          # -> 6
(* 1 2 3)             # -> 6

(def a @[1 2 3])
(def b (array/slice a))

#=> good way to clone array, a and b are different arrays

(map math/abs   [-2.9 -2.1 2.1 2.9])  # => @[ 2.9  2.1  2.1  2.9 ]
(map math/floor [-2.9 -2.1 2.1 2.9])  # => @[ -3   -3   2    2   ]
(map math/ceil  [-2.9 -2.1 2.1 2.9])  # => @[ -2   -2   3    3   ]
(map math/round [-2.9 -2.1 2.1 2.9])  # => @[ -3   -2   2    3   ]
(map math/trunc [-2.9 -2.1 2.1 2.9])  # => @[ -2   -2   2    2   ]

# in the file ex.janet

(main [_ & args]
      (print "write something and I'll echo it")
      (def x (getline))
      (print x))

# in the terminal:
# $ janet ex.janet
# write something and I'll echo it
# bla <- you wrote this
# bla

(buffer/bit (buffer/new-filled 1 (chr "0")) 4)
# => true

(-> 1 (+ 2) (+ 3))  # -> 6

(def b @"")
(def v (* 1000 (math/random)))
# => 912.753 can differ for you
(xprintf b "Value reached level %f" v)
# => nil
b
# => @"Value reached level 912.752790\n"