unify/optimize ascii/asciiz/byte/halfword/word into BIN directives
also lex strings to binary strings, why not

more useful string escapes e.g. \x

lex expressions in Lexer instead of its own separate lexer

;pseudo-instr for offsets not within 0x8000 range?
addiu   at, t0, 0x7FFF
sb      t1, 0x62FE(at)
;versus
sb      t1, r0+0xE2FD(t0)

directive aliases, are these right?
    DB = 'BYTE',
    DH = 'HALFWORD',
    DW = 'WORD',

add basic command-line interface (patch.lua)

add macros
implement push/pop/jpop as macros
be able to point to specific args of push/pop using variables
add file-reading directives (e.g. for automatic hook injection macros)
allow generation of shared object files (zelda overlays specifically)
http://wiki.cloudmodding.com/oot/Overlays#Relocation_Entry_Format

don't require colons for +/- labels (this shouldn't break anything right?)

write tests for everything (try to focus on code paths and edge cases)
test unary tokens in particular

improve parser terminology

add a gameshark writer

improve writer performance (just copypaste what you did in patch.lua)

long term: add delay slot warnings

externally document more stuff like syntax