Community documentation for Janet

(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!"

(inc 42)  # => 43
(map inc [1 2 3])  # => @[2 3 4]

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

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

(put-in  @{:a @{:aa 5} :b @{:bb 6}}  [:c]          9)  # => @{:a @{:aa 5} :b @{:bb 6} :c 9}
(put-in  @{:a @{:aa 5} :b @{:bb 6}}  [:a :aa]      9)  # => @{:a @{:aa 9} :b @{:bb 6}}
(put-in  @{:a @{:aa 5} :b @{:bb 6}}  [:a :cc :ddd] 9)  # => @{:a @{:cc @{:ddd 9} :aa 5} :b @{:bb 6}}

(put-in  @[:a :b @[:aa :bb :cc]]  [2 1] :zz )  # => @[:a :b @[:aa :zz :cc]]
(put-in  @[:a :b @[:aa :bb :cc]]  [5]   :z  )  # => @[:a :b @[:aa :bb :cc] nil nil :z]

(put-in  @[:a :b @[:aa :bb :cc]]  [4 0]   :zz )  # => @[:a :b @[:aa :bb :cc] nil @{0 :zz}]
(put-in  @[:a :b @[:aa :bb :cc]]  [4 :yy] :zz )  # => @[:a :b @[:aa :bb :cc] nil @{:yy :zz}]

(math/pow 10 3)   # => 1000
(math/cbrt 1000)  # => 10

# 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

(array/slice @[1 2 3] 0 0)  # => @[]
(array/slice @[1 2 3] 0 1)  # => @[1]
(array/slice @[1 2 3] 0 2)  # => @[1 2]
(array/slice @[1 2 3] 0 3)  # => @[1 2 3]
(array/slice @[1 2 3] 0 4)  # error: index out of range

(array/slice @[1 2 3] 1 1)  # => @[]
(array/slice @[1 2 3] 1 2)  # => @[2]

(array/slice @[1 2 3] 0 -1)  # => @[1 2 3]
(array/slice @[1 2 3] 0 -2)  # => @[1 2]
(array/slice @[1 2 3] 0 -3)  # => @[1]
(array/slice @[1 2 3] 0 -4)  # => @[]
(array/slice @[1 2 3] 0 -5)  # error: index out of range

(defn slurp-lines [path]
  (string/split "\n" (slurp path)))

(keyword "")
# => :

# slice with strings
(slice "Hello" 1)        # => "ello"
(slice "Playing" 0 -4)   # => "Play"
(slice "Playing" -4)     # => "ing"

# slice with keyword
(slice :hello 1)         # => "ello"

(map idempotent?  [ nil  true 97   'a   :a   "a"  ])
# =>             @[ true true true true true true ]

(map idempotent?  [  [97]   @[97]  {0 97}  @{0 97}  ])
# =>             @[  false  false  false   false    ]

(map idempotent?  [  (fn [])  even?  loop  file/open  ])
# =>             @[  true     true   true  true       ]

(map idempotent?  [  (file/temp)  (fiber/new (fn []))  ])
# =>             @[  true         true                 ]

(os/perm-string 420)    # => "rw-r--r--"
(os/perm-string 8r644)  # => "rw-r--r--"
(os/perm-string 493)    # => "rwxr-xr-x"
(os/perm-string 8r755)  # => "rwxr-xr-x"

(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"]

(map number? [nil   true  42   :a    "a"   []    {}    (fn []) ])
# =>        @[false false true false false false false false   ]

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