backy-back

stack lang

a little bit of forth, python & lisp

implied infix

1 + 1
is
(1 + 1)

to

1 1 +

or

a = 10

to

10 a !

assignment syntax

special case for infix assignment

a = 5

to

5 a !

instead of

a 5 =

type checking

steal type checking from WASM

https://binji.github.io/posts/webassembly-type-checking/

struct access

struct ball
  x float
  y float

var my-ball = ball(0, 0)

puts my-ball.x

keep assignment and equality explicit

set a 10

set set
:=  let
 =  equals or ==

add forth memory model

mem = bytearray(0x8000)

have modes: 8bit, 16bit, 32bit, 64bit

Review how Uxa does this

stack functions

push
pop
peek
print
get

typed version

object is a union, it can be a list or a void*

struct list {
    struct object *elem;
    struct object *next;
}

struct object {
    int tag;
    union {
        void *vs;
    } u;
}

include version numbers

version 0

heredocs

puts <<end
hello,
How are you doing today?
bye!
end

add rpn command

so I can write reverse polish notation as a statement

emit 42

rpn 42 emit

alt token parser

head, *tail = "one two three"

into

['one', ['two', 'three']]

infix

(1 + 2 + 3)

into

['+', ['1', '2', '3']]

puts (9 + 11)

into

['puts', [['+', ['9', '11']]]]

neoteric

double(10)

into

[double [infix [10]]]


puts double(10)

into

[puts [[double [infix [10]]]]]

comma must be followed bya whitespace?

into expresion

def double
    dup
    $ + $

into

( def double \n
    ( dup \n )
    ( $ + $ \n ) )

c ish syntax?

fn main {
    puts "hello"
}

into

( fn main { \n
    ( puts "hello" \n )
    } \n )

runtime

• server exe
• listen on tcp
• linked list of functions
• linked list of variables
• define new functions
• redefine functions
• call function
• list functions
• inspect global state

function details

functions include both source code and compiled versions