Prelude

Kex ships a small, focused standard library covering collections, strings, IO, math, and effectful primitives. Collections share enumeration operations through Enumerable.

Lists & ranges

collections.kex

let nums = [1, 2, 3, 4, 5]

nums.sum                        # 15
nums.map { |x| x * 2 }          # [2, 4, 6, 8, 10]
nums.filter(&.even?)            # [2, 4]
nums.find(&.even?)              # Just(2)
nums.contains?(3)               # true
nums.min                        # Just(1)

let r = 1..100
r.sum                           # 5050
r.map { |x| x * x }.take(3)     # [1, 4, 9]

Maps

maps.kex

var ages = { "alice": 30, "bob": 25 }
ages.put!("charlie", 35)
ages.delete!("bob")
ages.get("alice")               # Just(30)
ages.keys                       # ["alice", "charlie"]

Strings & chars

strings.kex

"hello".upperCase            # "HELLO"
"  hi  ".trim                # "hi"
"a,b,c".split(",")          # ["a", "b", "c"]
"a-b-c".contains?("-")       # true

'0'.digit?                   # true
'a'.alpha?                   # true
' '.space?                   # true

IO & Math

io-math.kex

IO.printLine("hi")            # stdout
Math.PI                       # 3.141592653589793
Math.sqrt(16.0)               # 4.0
Math.sin(0.0)                 # 0.0

Lazy streams

streams.kex

let naturals = Stream.Sequence(from: 0) { |n| n + 1 }
let primes = Stream.Sequence(from: 2) { |n| n + 1 }
  .filter do |n|
    (2..n - 1).all? { |d| n.modulo(d) != 0 }
  end

primes.take(5)                 # [2, 3, 5, 7, 11]