Parser

C2PO uses SLY to perform parsing. SLY works by using python annotations to define which parse rules result in calling which function. The parser takes a str as input, then outputs a cpt.Program. The parser does some context management in order to determine what to parse certain symbols as (i.e., whether a symbol is a signal or bound variable in a set aggregation operator), but in general leaves most context-sensitive tasks to the type checker.