Named_parameters.fold

--
-- Named parameters
-- http://rosettacode.org/wiki/Named_parameters#Fold
-- http://briancarper.net/blog/579/keyword-arguments-ruby-clojure-common-lisp
--

-- Named arguments
def range from: (start = 0) to: stop by: (step = 1) =
  if start >= stop
    []
  else
    [start & range from: start + 1 to: stop by: step]
  end

range from: 10 to: 200 by: 5


-- Implicit named arguments (all default arguments are named)
def translate :: lang: (`en | `ru) -> String -> String
def translate (lang = `en) message =
  match lang
  | `en -> English.translate message
  | `ru -> Russian.translate message
  end

translate lang: `en "Hello"


- Implementation:
    - records
    - mixfix operators


## Records

    if (a > 3) then: "yes" else: "no"



join (s1::String) (to s2::String) (with joiner::String = " ") -> String =
    s1 + joiner + s2


join (s1::String) (to s2::String) (with joiner::String = " ") -> String =


join "hello" to: "world" with: ", "
join("hello", to: "world", with: ", ")



range from: start = 0, to: stop, by: step = 1 =
    start == stop
        ? []
        : [start, (range from: (start + 1) to: stop by: step)...]

|| Function signature with named parameters.
range :: from: Int -> to: Int -> by: Int


|| Named application syntax

range from: 0 to: 100 by: 5

range from => 0 to 100 by => 5

range ~from: 0 ~to: 100 ~by: 5






let surround string (border = `Double) (padding = 0) =
    print ul (ho ^ (|string| + 2 * padding)) ur "\n"
          ve (" " ^ padding) string (" " ^ padding) ve "\n"
          dl (ho ^ (|string| + 2 * padding)) dr
    where ve, ho, ul, ur, dl, dr = border =>
    | `Round  -> ("\u2502", "\u2500", "\u256d", "\u256e", "\u2570", "\u256f")
    | `Bold   -> ("\u2503", "\u2501", "\u250F", "\u2513", "\u2517", "\u251b")
    | `Double -> ("\u2551", "\u2550", "\u2554", "\u2557", "\u255a", "\u255d")
    | `Dotted -> ("\u254e", "\u254c", "\u250c", "\u2510", "\u2514", "\u2518")
    | `Cross  -> ("\u2502", "\u2500", "\u253c", "\u253c", "\u253c", "\u253c")


    -> surround "Hello" padding: 1 border: `double
    ╔═══════╗
    ║ Hello ║
    ╚═══════╝

"hello" |> capitalize |> surround with: ("***", "***") |> print

"hello"
    => capitalize
    >> surround with: ("***", "***")
    >> print

"hello" => capitalize
           (surround with: ("***", "***"))
           print

dot =
  scale 2 (move (20, 20) (filled blue (circle 10)))


dot =
  circle 10
    |> filled blue
    |> move (20, 20)
    |> scale 2


dot =
  circle 10
    => filled blue
    >> move (20, 20)
    >> scale 2