Pry v0.3.1 is out!

[Bastiaan Veelo via Digitalmars-d-announce]

On Monday, 16 January 2017 at 22:29:01 UTC, Dmitry Olshansky 
wrote:
> I think left-recursion is better handled at the grammar level.
> What I currently have is parser combinators level where adding
> this transformation is awkward and too much magic IMO.

Handling left-recursion by grammar transformation often has 
unwanted side-effects (operator precedence) and eliminating 
indirect left-recursion this way can be impossible in practice. 
Depending on the complexity of the grammar, even identifying the 
recursive loop can be a challenge.

The trouble is that one can be happily implementing a parser or 
designing a grammar when suddenly for some input the parser hangs 
indefinitely. Users are likely quick to blame the parser lib, 
while in fact it is the grammar that has left-recursion. Hitting 
that roadblock is a real bummer.

In some cases the grammar is a given (by a standard for example) 
and transforming it to combat left-recursion can obfuscate it 
beyond recognition. Hardening Pegged to deal with the various 
kinds of left-recursion was very challenging, but easier than 
transforming the grammar I was dealing with (ISO 10206).