Running examples in 'rly-Ex.R' failed
The error most likely occurred in:

> ### Name: yacc
> ### Title: Build a parser
> ### Aliases: yacc
> 
> ### ** Examples
> 
> TOKENS = c('NAME', 'NUMBER')
> LITERALS = c('=','+','-','*','/', '(',')')
> 
> Parser <- R6::R6Class("Parser",
+   public = list(
+     tokens = TOKENS,
+     literals = LITERALS,
+     # Parsing rules
+     precedence = list(c('left','+','-'),
+                       c('left','*','/'),
+                       c('right','UMINUS')),
+     # dictionary of names
+     names = new.env(hash=TRUE),
+     p_statement_assign = function(doc='statement : NAME "=" expression', p) {
+       self$names[[as.character(p$get(2))]] <- p$get(4)
+     },
+     p_statement_expr = function(doc='statement : expression', p) {
+       cat(p$get(2))
+       cat('\n')
+     },
+     p_expression_binop = function(doc="expression : expression '+' expression
+                                                   | expression '-' expression
+                                                   | expression '*' expression
+                                                   | expression '/' expression", p) {
+       if(p$get(3) == '+') p$set(1, p$get(2) + p$get(4))
+       else if(p$get(3) == '-') p$set(1, p$get(2) - p$get(4))
+       else if(p$get(3) == '*') p$set(1, p$get(2) * p$get(4))
+       else if(p$get(3) == '/') p$set(1, p$get(2) / p$get(4))
+     },
+     p_expression_uminus = function(doc="expression : '-' expression %prec UMINUS", p) {
+       p$set(1, -p$get(3))
+     },
+     p_expression_group = function(doc="expression : '(' expression ')'", p) {
+       p$set(1, p$get(3))
+     },
+     p_expression_number = function(doc='expression : NUMBER', p) {
+       p$set(1, p$get(2))
+     },
+     p_expression_name = function(doc='expression : NAME', p) {
+       p$set(1, self$names[[as.character(p$get(2))]])
+     },
+     p_error = function(p) {
+       if(is.null(p)) cat("Syntax error at EOF")
+       else           cat(sprintf("Syntax error at '%s'", p$value))
+     }
+   )
+ )
> 
> parser <- rly::yacc(Parser)