Re: Parsing Expression Grammar

"Hans-Peter Diettrich" <DrDiettrich@compuserve.de> wrote


> Paul Mann wrote:
>>
>> "Chris F Clark" <cfc@shell01.TheWorld.com> wrote in message
>> > But, as a potential language designer, you need to think long and hard
>> > about why you want to create a language which has no LL(1) grammar.
>>
>> Answer: Readability for human's sake.
>
> Do you really think that humans prefer harder to "parse" languages?
> Lookahead and backtracking affect humans as well as programs.




Yes humans do prefer harder-to-parser languages. Example: English.


And the computer should serve the human not the other way around.
That's why we have invented LALR(1), LR(1) and GLR parsing.


>> Why constrain your language to LL(1) when LALR(1) tools are available?
>
> Why write small and fast programs when users have so much memory and so
> fast processors?


Why program in more powerful harder to write programming languages
such as C and C++, when assembly language is available ????


> [Stuff that's easy for computers to parse isn't always easy for people to
> read or write. The classic example is Pascal vs. PL/I semicolons, where
> Pascal's separator semicolons are syntactically elegant but quite error
> prone. -John]


Yes, and the space used for beginning a comment in OS JCL was the most
common cause of errors according to a study.


Some programmer probably found it easier to program it that way.




Paul Mann
http://parsetec.com

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