Please use 
installExprFunction() for a better
debugging experience (Shiny 0.8.0). If the expr and quoted parameters are not needed, please see
quoToFunction() (Shiny 1.6.0).
exprToFunction(expr, env = parent.frame(), quoted = FALSE)Similar to installExprFunction() but doesn't register debug hooks.
installExprFunction() for the modern approach to converting an expression to a function