prettyerr 0.0.1

Pretty error messages

Pretty Err

A simple library for printing modern, source-annotated error messages.

Features

• source span annotation
• color output
• multiple non-overlapping spans
• zero-width spans

Install

pip install prettyerr

Example

Say you have the following source code that contains an error

def repeat(message: str, times: int) -> str:
    return message * times

result = repeat("hello", "3")
print(result)

A nice error message might look something like this

Error: type mismatch for argument `times`

    ╭─[path/to/py_example.py:4:10]
  4 | result = repeat("hello", "3")
    ·          ──┬───          ─┬─
    ·            │              ╰─ argument given is type 'str'
    ·            ╰─ `repeat` function's second argument `times` expects an 'int'
    ╰───
  help: Consider changing string literal "3" to integer 3

To render this error message:

from prettyerr import Error, PointerMessage, Span, SrcFile

src = """\
def repeat(message: str, times: int) -> str:
    return message * times

result = repeat("hello", "3")
print(result)
"""

e = Error(
    SrcFile(py_src, "path/to/py_example.py"),
    title="type mismatch for argument `times`",
    pointer_messages=[
        PointerMessage(span=Span(82, 88), message="`repeat` function's second argument `times` expects an 'int'"),
        PointerMessage(span=Span(98, 101), message="argument given is type 'str'"),
    ],
    hint='Consider changing string literal "3" to integer 3',
)
print(e)

Tasks

• set up slaving to dewy-lang repo error.py
• set up workflow to periodically check for changes to error.py (maybe once per week?)
  • on change, create a PR using the newest version of the error.py
  • run tests to make sure everything is still working
  • if tests fail, note that in the PR (e.g. if I move error.py, the script would fail to pull it in, etc.)
  • PR should assign me so that I know to deal with it
  • TBD if a previous PR hasn't been merged what to do, perhaps just let it make a new PR?
• improve README