#!/usr/bin/env nomsu -V5.12.12.8
#
    A library for simple object oriented programming.
    
test:
    an (Empty) is a thing
    a (Dog) is a thing:
        [$it, $its] = [Dog, Dog]
        ($its|set up) means:
            $its.barks or= 0
        
        [$its|bark, $its|woof] all mean:
            $barks = [: for $ in 1 to $its.barks: add "Bark!"]
            return ($barks|joined with " ")
        
        ($it|gets pissed off) means: $it.barks += 1
    (Dog).genus = "Canus"
    $d = (a Dog with {barks: 2})
    assume "\$d" == "Dog {barks: 2}"
    assume (type of $d) == "Dog"
    assume ($d is a "Dog")
    assume $d.barks == 2
    assume (($d|bark) == "Bark! Bark!")
    assume (($d|woof) == "Bark! Bark!")
    $d|gets pissed off
    assume ($d.barks == 3)
    assume (($d|bark) == "Bark! Bark! Bark!")
    assume ($d.genus == "Canus")
    assume ("\($d.class)" == "Dog")
    assume ($d.genus == "Canus")
    assume ($d.barks == 3)
    $d2 = (a Dog)
    assume ($d2.barks == 0) or barf "Default initializer failed"
    with {$d: a Dog with {barks: 1}}:
        assume (($d|bark) == "Bark!")
    
    a (Corgi) is a thing:
        [$it, $its] = [Corgi, Corgi]
        $it [set up, gets pissed off] like a (Dog)
        ($it|as text) means "Dogloaf \{: for $k = $v in $it: add $k = $v}"
        ($its|sploot) means "sploooot"
        [$its|bark, $its|woof] all mean:
            $barks = [: for $ in 1 to $its.barks: add "Yip!"]
            return ($barks|joined with " ")
    
    $corg = (a Corgi)
    assume ($corg.barks == 0)
    assume "\$corg" == "Dogloaf {barks: 0}"
    with {$d: a Corgi with {barks: 1}}:
        assume (($d|sploot) == "sploooot") or barf "subclass method failed"
        assume (($d|bark) == "Yip!") or barf "inheritance failed"
        assume (($d|woof) == "Yip!")
    
    with {$d: a Dog with {barks: 2}}:
        assume (($d|bark) == "Bark! Bark!")
    
    a (Vec) is a thing with {x, y}:
        $its = (Vec)
        ($its|+ $other) means (Vec {x: $its.x + $other.x, y: $its.y + $other.y})
    
    assume ((Vec {x: 1, y: 2}) + (Vec {x: 10, y: 10})) == (Vec {x: 11, y: 12})
    assume (((Vec {x: 1, y: 2}) + (Vec {x: 10, y: 10})) != (Vec {x: 0, y: 0}))

[..]
    $it can $actions like a $class, $it can $actions like an $class
    $it has $actions like a $class, $it has $actions like an $class
    $it $actions like a $class, $it $actions like an $class
..all compile to:
    $lua = (Lua "")
    $class_expr = ($class as lua expr)
    $lines = []
    for $a in $actions:
        $lines|
            add "\($it as lua expr).\($a.stub|as lua id) = \$class_expr.\($a.stub|as lua id)"
    $lua|add $lines joined with "\n"
    return $lua

$METAMETHOD_MAP = {..}
    "as text": "__tostring", "clean up": "__gc", "+": "__add", "-": "__sub"
    "*": "__mul", "/": "__div", negative: "__unm", "//": "__idiv", mod: "__mod"
    "^": "__pow", "&": "__band", "|": "__bor", "~": "__bxor", "~": "__bnot"
    "<<": "__bshl", ">>": "__bshr", "==": "__eq", "<": "__lt", "<=": "__le"
    "set 1 =": "__newindex", size: "__len", iterate: "__ipairs", "iterate all": "__pairs"

(($ as text like a dict)'s meaning) = ({}'s metatable).__tostring
externally (a class named $classname with $members ((initialize $it)'s meaning)) \
..means:
    $class = {__type: $classname}
    $class.__index = $class
    $class.class = $class
    $class.__tostring = ($ -> "\($.__type) \($ as text like a dict)")
    $class.__eq = ({}'s metatable).__eq
    $class.__len = ({}'s metatable).__len
    if $members:
        $class.__members = $members
        $class.__newindex = (..)
            for ($its $key = $value):
                if $members.$key:
                    rawset $its $key $value
                ..else:
                    barf "Cannot set \$key, it's not one of the allowed member fields."
    
    set $class's metatable to {..}
        __tostring: $class -> $class.__type, __call: for ($class with $initial_values):
            if ($initial_values == (nil)): return $class
            set $initial_values's metatable to $class
            if $initial_values.set_up:
                $initial_values|set up
            return $initial_values
    
    if ((initialize)'s meaning):
        initialize $class
        for $stub = $metamethod in $METAMETHOD_MAP:
            if $class.($stub|as lua id):
                $class.$metamethod = $class.($stub|as lua id)
    
    return $class

[..]
    a $classname is a thing with $members $class_body
    an $classname is a thing with $members $class_body
..all compile to:
    $class_id = ($classname.stub|as lua id)
    if $class_body:
        $body_lua = ($class_body as lua)
        $body_lua|remove free vars [$class_id]
        $body_lua|declare locals
    
    return (..)
        Lua "
            \$class_id = a_class_named_1_with(\(quote $classname.stub), \($members as lua)\((Lua ", function(\$class_id)\n    \$body_lua\nend") if $class_body else "")\
            ..)
            a_\$class_id = function(initial_values) return \($classname.stub|as lua id)(initial_values or {}) end
            an_\$class_id, a_\($class_id)_with, an_\($class_id)_with = a_\$class_id, a_\$class_id, a_\$class_id"

[a $classname is a thing $class_body, an $classname is a thing] all parse as (..)
    a $classname is a thing with (nil) $class_body