Pest grammar for process calculus

proc_calc.pest

var = {('a'..'z') ~ ('a'..'z'|'A' .. 'Z'| '0' .. '9')*}
num = {"-"? ~ ('0'..'9')+}
opr = {"+"|"*"|"-"|"/"}
chan = {('A'..'Z') ~ ('a'..'z'|'A' .. 'Z'| '0' .. '9')*}
expr = {term ~ opr ~ expr | term}
term = {var | num | "("~ expr ~")"}
bexpr = {"true" | "false" | expr ~ "<" ~ expr}

def_list = { def ~ "\n" ~ def_list | def }
def = { chan ~ "=" ~  proc_list | proc_list}
proc_list = {procs ~ "|" ~proc_list | procs}
procs = {proc_ ~ ";" ~ procs | proc_ ~";"?}
proc_ = {"done" | var ~ "<-" ~ chan | expr ~ "->" ~ chan | "[" ~ bexpr ~ "]" |
         chan}
WHITESPACE = _{" "}