Community documentation for Janet

(var a false)
(defer (set a 42) 
  (set a true)
  (error "Oh no!"))
# error: Oh no!

(pp a) # => prints 42

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

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

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

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

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

# From: https://codeberg.org/veqq/janetdocs/src/commit/54a964d1a35920af2655c4932a9b51379e8b9380/helpers.janet#L52

(defn current-account [request]
  (def login (get-in request [:session :login] ""))
  (joy/db/find-by :account :where {:login login}))

(blshift 8 2)  # => 32

(eachk k [1 2 3] (print k))
# prints 0
# prints 1
# prints 2
# for indexed collections indices are printed  

(eachp [k v] {:a "a val" :b "b val" :c "c val"} (print k " - " v))
# prints c - c val
# prints a - a val
# prints b - b val

janet:2:> (all true? [true true false])
false
janet:3:> (all even? [2 4 6 7])
false
janet:5:> (all even? [2 4 6])
true

(drop 1 [1 1 2 3 5 8])
# => '(1 2 3 5 8)

# sh/$ can't expand "~" so you must build it:

# (def key "D8E4DB18BF87FLEW7402BBE3AA91B16F4A65C4C9") # use your gpg key ID
(defn copy-and-encrypt-password-store [key-id]
    (with [out (file/open "pass-backup.tar.gz.gpg" :w)]
        (sh/$ tar -czf - ,(string (os/getenv "HOME") "/.password-store")
            | gpg --encrypt --recipient ,key-id > ,out)))

# tar -cz ~/.password-store/ | gpg --encrypt --recipient YOUR_KEY_ID > pass-backup.tar.gz.gpg

# absolute value of negatives, ignore positives
(keep |(if (< $ 0) (- $) nil) [-1 2 -3 -4 -5 6]) # -> @[1 3 4 5]

# halves each even number, ignores odds
(keep |(when (even? $) (/ $ 2)) [1 2 8 7 -2])    # -> @[1 4 -1]

(do
  (var a 88)
  (+= a 12))  # 100

(slice [:a :b :c :d])  # => (:a :b :c :d)

(slice [:a :b :c :d] 0)  # => (:a :b :c :d)
(slice [:a :b :c :d] 1)  # => (:b :c :d)
(slice [:a :b :c :d] 3)  # => (:d)
(slice [:a :b :c :d] 4)  # => ()
(slice [:a :b :c :d] 5)  # error: index out of range

(slice [:a :b :c :d] -1)  # => ()
(slice [:a :b :c :d] -2)  # => (:d)
(slice [:a :b :c :d] -4)  # => (:b :c :d)
(slice [:a :b :c :d] -5)  # => (:a :b :c :d)
(slice [:a :b :c :d] -6)  # error: index out of range

(slice [:a :b :c :d] 0 0)  # => ()
(slice [:a :b :c :d] 0 1)  # => (:a)
(slice [:a :b :c :d] 0 4)  # => (:a :b :c :d)

(slice [:a :b :c :d] -1 -1)  # => ()
(slice [:a :b :c :d] -2 -1)  # => (:d)
(slice [:a :b :c :d] -5 -1)  # => (:a :b :c :d)

(slice [:a :b :c :d] 1 0)  # => ()
(slice [:a :b :c :d] 4 0)  # => ()
(slice [:a :b :c :d] -1 -2)  # => ()
(slice [:a :b :c :d] -1 -5)  # => ()

(string/bytes "foo")  # => (102 111 111)
(string/from-bytes 102 111 111)  # => "foo"
(string/from-bytes (splice (string/bytes "foo")))  # => "foo"

(map (fn [x] x)        "foo")  # => @[102 111 111]
(map string/from-bytes "foo")  # => @["f" "o" "o"]

(defn string/explode [s] (map string/from-bytes s))
(string/explode "foo")  # => @["f" "o" "o"]

(/ 1 2 3)
# => 0.166667

(extreme < [1 2 3])  # => 1
(extreme > [1 2 3])  # => 3