nomsu/lib/things.nom

#!/usr/bin/env nomsu -V6.14
#
    A library for simple object oriented programming.
    
test:
    an (Empty) is a thing
    a (Dog) is a thing:
        ($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)
    $d2 = (a Dog)
    unless ($d2.barks == 0):
        fail "Default initializer failed"
    
    with [$d = (a Dog with {.barks = 1})]:
        assume (($d, bark) == "Bark!")
    
    a (Corgi) is a thing:
        $it [set up, gets pissed off] like a (Dog)
        ($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 [$d = (a Corgi with {.barks = 1})]:
        unless (($d, sploot) == "sploooot"):
            fail "subclass method failed"
        
        unless (($d, bark) == "Yip!"):
            fail "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, + $other) means (Vec {.x = ($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 metatable).__tostring
externally (a class named $classname with $members $(initialize $)) 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:
                    fail "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 $):
        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)
                            local it, its = \$class_id, \$class_id;
                            \$body_lua
                        end
                    ")
                ) 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