add translate function
add pic_dict_has
refactor translate to use pic_dict instead of boxes
cosmetic changes
cosmetic changes again
function reorder
add pic_void macro
rewrite iteration with recursion. since we have variable-length arena
now, it is no longer required to avoid big arena consumption.
s/formals/formal/g
refactor macroexpand_define. make use of macroexpand_lambda function
refactor macroexpand_lambda
support let-syntax
Merge branch 'let-syntax2'