Primarily a brainstorming exercise to test out the feel of the language design thus far.

Bool def.lps

module
    exports #Bool #False #True

def Bool

def False <| Bool
    and False -> False
    and True -> True
    or False -> False
    or True -> True
    not -> True

def True <| Bool
    and True -> True
    and False -> False
    or True -> True
    or False -> True
    not -> False

config.lpc

module-manifest
    M1 -> </lapis/std/A>
    M2 -> <http://example.com/src/B>

module-config
    N1 -> M1
    N2 -> M2 T1:M1.Foo T2:M1.Bar

app-view
    </> -> N1
    </Baz> -> N2

Expr.lps

module :Int :Bool
    exports Expr

data Expr :_ => Expr Int
    I value: Int
    Add
        left: Expr Int
        right: Expr Int
    Mul
        left: Expr Int
        right: Expr Int

data Expr :_ => Expr Bool
    B value: Bool
    Eq
        left: Expr Int
        right: Expr Int

protocol Expr :a
    eval -> a

trait I
    eval -> $ value

trait B
    eval -> $ value

trait Add
    eval -> $ left eval + $ right eval

trait Mul
    eval -> $ left eval * $ right eval

trait Eq
    eval -> $ left eval = $ right eval

Expr2.lps

module
    exports Expr

data Pair :a :b
    Pair 
        fst: a
        snd: b

data Expr :_ => Expr Int
    Lit value: Int
    Plus 
        e1: Expr Int
        e2: Expr Int

data Expr :_ => Expr Bool
    Equals
        e1: Expr Int
        e2: Expr Int

data Expr :a => Expr a
    Cond
        e1: Expr Bool
        e2: Expr a
        e3: Expr a

//FIXME
data Expr :a :b => Expr a
    Fst e: Expr (Pair fst: a snd: b)

//FIXME
data Expr :a :b => Expr b
    Snd e: Expr (Pair fst: a snd: b)

//FIXME
data Expr :a :b => Expr (Pair a: a b: b)
    Tuple
        e1: Expr a
        e2: Expr b

protocol Expr :a
    eval -> a
 
trait Lit
     eval -> $ value

trait Plus
    eval -> $ e1 eval + $ e2 eval

trait Cond
    eval ; $ e1 eval = True -> e2 eval
    eval ; $ e1 eval = False -> e3 eval

trait Equals
    eval -> $ e1 eval = $ e2 eval

trait Tuple
    eval -> Pair fst: $ e1 eval snd: $ e2 eval

trait Fst
    eval -> $ e eval fst

trait Snd
    eval -> $ e eval snd

FizzBuzz.lps

module :Int :String
    exports Int

trait Int
    fizzBuzz ; 3 divides $ -> "Fizz"
             ; 5 divides $ -> "Buzz"
             ;             -> `#{$}`

Pair.lps

module
    exports Pair

data Pair :a :b
    Pair left: a right: b

trait Pair
    + Pair :left :right -> Pair left: left + $ left
                                right: right + $ right

Palindrome.lps

module :String
    exports String

trait String
    isPalindrome -> $ reverse = self

Point2.lps

module :Int
    exports Point2

data Point2
    Point2 x: Int y: Int

trait Point2
    + Point2 :x :y -> Point2 x: x + $ x
                             y: y + $ y

scratchpad.hs

-- data introduced by an unfold | anamorphism
-- A Recursive Datatype is the Least Fixpoint of a Functor

data Tree a = Leaf a | Branch (Tree a) a (Tree a)

newtype Tree a = Tree {unNode :: Either a (Tree a, a, Tree a))}

data List a = Nil | Cons a (List a)

newtype List a = List {unCons :: Maybe (a, List a)}

Pattern Matching: http://lambda-the-ultimate.org/node/2927#comment-43259
http://lambda-the-ultimate.org/node/3096

Predicate Dispatch:
From wikipedia: "...extensions with identical or overlapping predicates created
by different developers may interfere with each other in unanticipated ways.
In this respect it is similar to aspect-oriented programming.

http://c2.com/cgi/wiki?PredicateDispatching

From https://groups.google.com/forum/#!msg/comp.lang.lisp/HQFMhGrKrcg/y3wM893uAwQJ:
"Unfortunately, predicate dispatch doesn't work in
the general case, and it shows in the Clojure solution: There are corner
cases there when two methods are applicable at the same time where the
ways to disambiguate them are only very ad hoc."

/////
I suspect similar issues will arise with arbitrary pattern matching on anonymous structures

//
http://lambda-the-ultimate.org/node/1960#comment-23790
http://www.artima.com/weblogs/viewpost.jsp?thread=166742

• Use Lapis syntax for config?
• *.lpc
• integrating 3rd party configs?

-use a manifest file separate from the config file

If a definition has no methods or properties, can it not be constructed?
"You can not instantiate a definition which does not define or inherit methods"