tclem / megaparsec-play

Playing with Ripper and Megaparsec

Parsing Ripper output with Megaparsec.

This is just a scratch pad for playing with and understanding the Haskell library Megaparsec. To do so, I tried to write a parser for Ruby's Ripper s-expression output. Ripper let's you get s-expressions for Ruby code like so:

>> require 'ripper'
>> require 'pp'
>> Ripper.sexp('def hello; puts "hey"; end')
=> [:program, [[:def, [:@ident, "hello", [1, 4]], [:params, nil, nil, nil, nil, nil, nil, nil], [:bodystmt, [[:command, [:@ident, "puts", [1, 11]], [:args_add_block, [[:string_literal, [:string_content, [:@tstring_content, "hey", [1, 17]]]]], false]]], nil, nil, nil]]]]

Or alternatively, pipe in anything form stdin:

echo 'def hello; puts "hey"; end' | ruby -r ripper -r pp -e "pp Ripper.sexp(STDIN.read)"

This is the input to the parser.