#!/usr/bin/env perl 

# x is a global variable which can be accessed from other namespaces
# ex: if we were in the namespace ONE::TWO then access 'a' with ONE::TWO::W
# it is mandatory for globals to be uppercased
global W = 2

# fibonacci sequence with ret value cached
fun fibonacci(n) is cached {
   n < 2 ? n : _F_(n - 1) * _F_(n - 2)
}

# forever loop
forever {
   "Hello World".say
}

# async forever loop
async forever {
   ["Hello", "World"].each{ .uc.shuffle + _ }
}

# fun fibonacci asyncronously
async fibonacci(10)

# Working with blocks
LABEL: {
   say "block one"

   # recurse to the current block
   _BLOCK_ if "one".shuffle(3)  = "one"
   # recurse to the current block too
   _LABEL_ if "one".shuffle(3) = "one"

   {
      say "block two"

      # recurse to LABEL
      _LABEL_ if "two".shuffle(4) = "two"
      # recurse to the current block
      _BLOCK_
   }
}

## Numbers
3.times{ ... } # ...: unimplemented

## Hash
# declare a hash and store it in a lexically scope variable
let bhash = {one: 2, two: 1} # or
let ahash = Hash.new(
                     2   -> two,
                     3   -> "this three",
                     one -> 1,
                    ) # can replace '->' with ','

# declaring a code/block
let code = {
   let(k, v) = (_[0], _[2])
   say "#k, #{v isa Num ? v + 1 : v.uc }"
}

code(k, v) foreach k,v in ahash
ahash.each_kv{ a.say; b.say }

# _ is a topic variable
hash.keys{ (_ + .lc).say }

ahash{one}.say # accessing elements
ahash{one, 2, 3}.each{ ... } # returns an array
ahash{one, 2, 3} = ["One", 2, "ThReE"] # change values

let key = "Hello"
say ahash{key} if ahash.exists(key)

del key # delete lexical var 'key'

## Arrays
let array  = ["one", 2, 3] # or
let barray = Array.new("one", 2, 3)
array.say
array.each{ ... }.grep{ ... }

let r = 3..4 # returns an array of values ranging from 3 to 4
r.each { .say }

# access values
barray[0].say
array[2..4].each({...})

# lvalue
array[0..1] = qw(i j)

'a'..'z'.each{ ahash.exists(_) && .say }

## Complex data structures
let wtf = {
   one   -> [ { two -> 3, three -> 4 }, [qw(a b c d)] ],
   two   -> do { ... },
   three -> True ? [ { one -> 1, two -> 2 } ] : do { ... },
}

let b = [wtf, True]

## Working with Files
const file = "/path/to/file"
<file>.each_line{ .uc.say } # <a> open file "a" for reading if exists and return the File object
<>.each_line{ ... } # read from standard input

# flow constructs
while (True) { ... }
foreach v in array { ... }

# classes
class Person { ... }
class Student << Person {
   has class is rw
   has notes is ro

   # multiple dispatch
   multi method get_nodes(v) {
      self.notes.each{ _ > v}
   }

   multi method get_nodes(v, k) {
      self.notes.each{x < _ < k}
   }
}