trifecta | CLI tool that simplifies inspecting Kafka messages | Pub Sub library

The second parser would indeed consume the "qwe" part if only it was given a chance to run. But it isn't given such chance.

Look at the definition of (<|>) for Parser:

skipMany p applies the parser p zero-or-more times. Operationally, it goes something like this:

1. Attempt to apply p.
2. If p succeeded, repeat step 1.
3. If p failed without consuming input, succeed and return (). (This is what the “zero” in “zero-or-more” means.)
4. If p failed after consuming some input, report the failure.

Let's look at how skipSymbol operates on the input ).

1. Parsec tries the left hand choice of skipSymbol, namely skipMany (char '(').
2. skipMany (char '(') attempts to apply char '(', which fails without consuming input because the input character is ).
3. Because char '(' failed without consuming input, skipMany (char '(') succeeds without consuming input. This means the other choices in skipSymbol won't be attempted.
4. The current input character is still ) (which is what causes parse3Digits to later fail).

As noted in the comments, the fix is to change the definition of skipSymbol to

On Linux I needed to install zlib outside of cabal, you might need to do that. I see that in your list of failed packages.