The world's shortest complete monadic parsing tutorial

#1

Read the world’s shortest complete monadic parsing tutorial in the Quick Start section of the README for purescript-parsing GitHub - purescript-contrib/purescript-parsing: A parser combinator library based on Parsec

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#2

It’s great to see more docs! Good job.

It might be helpful to clarify:

That operator will first try the left parser and if that fails, then it will backtrack the input string and try the right parser.

This is a common point of confusion in newcomers, who often assume that parsers always backtrack on an error. However, this is a great way to get really terrible parser errors! The current implementation only backtracks as long as no input was consumed. Otherwise you need to explicitly opt-in to backtracking via try on the minimal lookahead you need to commit to a branch. try will reset the parser input state on failure, allowing alt to backtrack.

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#3

Yeah good idea I will clarify that, thanks @natefaubion .

#4

It might be helpful to clarify:
The current implementation only backtracks as long as no input was consumed .

I added that clarification to the README.

https://pursuit.purescript.org/packages/purescript-parsing

I also added more explanation about this in the documentation for the Alt instance.

https://pursuit.purescript.org/packages/purescript-parsing/docs/Text.Parsing.Parser#t:ParserT

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