### Parsing with specified error messages

Source: https://github.com/ekmett/trifecta/wiki/Tips-&-FAQs

This code shows how to improve error messages by using the `<?>` combinator to provide descriptive labels for parser failures. This makes debugging much easier by indicating what was expected.

```haskell
var = some $ (satisfy isAlphaNum <?> "alphanums")
num = some $ (satisfy isDigit <?> "digits")
program = var >> num >>  return ()
main = parseTest program "foo!"
```

--------------------------------

### Parsing with unspecified error

Source: https://github.com/ekmett/trifecta/wiki/Tips-&-FAQs

This code demonstrates a scenario where a parser combinator results in an unhelpful 'unspecified error' message. This often occurs when combinators like `satisfy` are used without providing specific error messages.

```haskell
var = some $ satisfy isAlphaNum
num = some $ satisfy isDigit
program =  var >>  num >>  return ()
main = parseTest program "foo!"
```

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