Community documentation for Janet

(* 3 4 5)          # => 60
(product [3 4 5])  # => 60

(last "hello")
# => 111

(os/time)  # => 1593838384
(os/date)  # => {:month 6 :dst false :year-day 185 :seconds 8 :minutes 53 :week-day 6 :year 2020 :hours 4 :month-day 3}
(os/mktime (os/date))  # => 1593838390

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

(as-> [1 2 3] _ 
  (map inc _)
  (sum _)
  (- _ 10)
  (< _ 0))
# -> true

# same as
(< (- (sum (map inc [1 2 3])) 10) 0)

(invert :yo)
# => @{111 1 121 0}

(def buf-bytes 12)

(var new-buffer (buffer/new buf-bytes)) #--> @""

(buffer/push new-buffer "hello, world") #--> @"hello, world"

(let [x 10]
  (unless (= x 10)
    (print "x is not 10!")
  )
)

# => nil

(let [x 5]
  (unless (= x 10)
    (print "x is not 10!")
  )
)

# => "x is not 10!"

(var x 1)
(+= x 2 3 4)
# x = 10

(def t @{:a 1 :b 2 :c @[1 2 3]})
(def ct (table/clone t))

(put ct :a 3) # => @{:c @[1 2 3] :a 3 :b 2}
(pp t) # => @{:c @[1 2 3] :a 1 :b 2}

(update ct :c array/concat 4) # => @{:c @[1 2 3 4] :a 3 :b 2}
(pp t) # => @{:c @[1 2 3 4] :a 3 :b 2}
# array under key :c is shared between tables!

(seq [i :range [0 3]
      j :range [0 3]
      :let [c (string/format "%c" (+ 97 i))]
      :when (and (even? i) (even? j))]
  [(keyword c) j])
# => '@[(:a 0) (:a 2) (:c 0) (:c 2)]

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

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

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

(print
  (prompt :a 
          (for i 0 1000000000000 
            (print (string "i=" i))
            (if (= i 2) 
                (return :a 10)))))
# output:
# i=0
# i=1
# i=2
# 10

# janet 1.10.1

(array/peek @[])     # => nil
(array/peek @[1])    # => 1
(array/peek @[1 2])  # => 2

(array/peek [1 2])           # error: expected array, got tuple
(array/peek (array [1 2]))   # => (1 2)
(array/peek (array ;[1 2]))  # => 2

(def a @[])
(array/push a 1)  # => @[1]
a                 # => @[1]
(array/push a 2)  # => @[1 2]
a                 # => @[1 2]