On Sat, Jun 15, 2013 at 7:21 PM, Zack Maril <thewitzb...@gmail.com> wrote:
> Why does instaparse not throw errors? Curious about the reasoning behind > this design. > -Zack > I'm not sure what you mean. It does throw errors for certain kinds of invalid grammars and other fatal problems. Perhaps what you're asking is why a string that doesn't fit the grammar will return a failure object. There are several reasons: 1. In my view, it's not really an error -- the parser should return some kind of value that indicates that the string didn't match the parser, and the value should contain information about why it didn't match the parser. It's sort of like choosing to return NaN rather than throwing an error for certain arithmetic ops. 2. The failure object is a simple Clojure map that can be explored, serialized, whatever. (I've chosen to print it somewhat like a thrown error, but it is in fact a value). 3. More consistent when you look at things like the total parse mode, which need to indicate parse failure and return a valid parse simultaneously. You can't do that if the only way to indicate failure is by throwing an error. 4. Makes it possible to chain the output of a parser directly to the transform function. 5. Makes it possible to do things like mapping a parser across a collection of strings to parse. -- -- You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com Note that posts from new members are moderated - please be patient with your first post. To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en --- You received this message because you are subscribed to the Google Groups "Clojure" group. To unsubscribe from this group and stop receiving emails from it, send an email to clojure+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
