notes.txt

RESERVED CHARS:
_: placeholder marker during increment
@: extra placeholder
they're not used for anything permanent

num := 0|[1-9][0-9]*

char := [^\]|\n|\\|\u|\a
builtin := quote
         | eq?
         | if
         | c[ad]+r
         | args
         | c[ad]+r-args
         | print
         | ...
item := Lnum:num
      | "char*
      | Bbuiltin

contitem := NEXT num
          | CONS num
          | DO item

CURRENT num
CONT
contitem
contitem
...
CONTEND
ARGS
num
num
...
ARGEND
HEAP
ITEM num item
ITEM num item
ITEM num item
...
HEAPEND

A function is a list.
To call a function:
 - push the args to ARGS
 - push a POPARGS continuation
 - evaluate the function

builtins:
 [X] quote
 [X] print
 [X] args
 [X] c[ad]+r
 [X] c[ad]+r-args
 [X] cons
 [X] if
 [X] eq?
 [X] str-concat
 [X] str-reverse-concat
 [X] str-concatl
 [X] str-reverse-concatl
 [ ] str-uncons
 [ ] str-unpack
 [X] add
 [X] dec
 [ ] digit-mul (?)
 [ ] lte?
 [ ] collect

Plan
How continuations work:
  DO:
      if current.head is a builtin:
          set current to current.tail
          ... do builtin stuff on current ...
          set current to the result
      else: (current.head is likely a cons cell)
          push current.tail to ARGS
          set current to current.head
          push POPARGS continuation
          Check for repeated POPARGS continuations and simplify
          eval current
  TAIL value:
      push CONS current
      if value is nil:
          set current to nil
      else value is a cons cell:
          push TAIL value.tail
          set current to value.head
          eval current
  CONS value:
      create new cons cell Lvalue:current
      set current to result
  POPARGS:
      pretty self-explanatory
How eval current works:
  if current is a cons cell:
      if current.head is Bquote:
          set current to current.tail.head
      else if current.head is Bif:
          set current to current.tail.head
          push TAILIF current.tail.tail
          goto eval current
      else:
          push DO
          push TAIL current.tail
          set current to current.head
          goto eval current
  else current is not a cons cell:
      do nothing

ARGS grows UP
CONT grows UP
HEAP grows UP