`couldn't process CM file: expected a class`

jez commented 2 years ago

Environment

VS Code version: n/a
Millet version: 71988b9cfea4faed3c0aa77ad5f417895a55f99d
OS version: macOS 10.15.7

Steps to reproduce

git clone https://github.com/jez/multi-grep
cd multi-grep
mv multi-grep.cm sources.cm # see issue #3
~/github/millet/target/debgug/cli

Expected behavior

no error

Actual behavior

❯ ~/github/millet/target/debug/cli
Error: /Users/jez/Dropbox/Documents/Programming/cli/multi-grep/sources.cm: couldn't process CM file: expected a class

Caused by:
    expected a class

It would be nice to at least know which line number of the CM file failed to parse, so I could know what the problem is. The contents of the CM file in question:

Group is
  $/regexp-lib.cm
  vendor/cmlib/cmlib.cm

  src/prelude.sml : succ-ml
  src/util.sml : succ-ml

  src/options.sml : succ-ml

  src/main.sig
  src/main.sml : succ-ml

azdavis commented 2 years ago

yeah, i put more effort into having good error locations etc for sml errors, while the cm error reporting is far more rudimentary.

in this case i’m thinking the error is because the class (the thing after the :) isn’t understood by millet. specifically “succ-ml”. millet only knows about a few classes, and actually allows processing even fewer (cm and sml only).

classes millet can parse from a string: https://github.com/azdavis/millet/blob/71988b9cfea4faed3c0aa77ad5f417895a55f99d/crates/cm/src/types.rs#L186
logic that rejects all but sml and cm: https://github.com/azdavis/millet/blob/71988b9cfea4faed3c0aa77ad5f417895a55f99d/crates/cm/src/lower.rs#L24

azdavis commented 2 years ago

i think instead of having an exhaustive list of classes (i think it’s possible to define arbitrary cm classes with user code?) i could just keep it a string and then only accept some, like “sml”, “cm”, and “cmfile”. that would improve the error here

azdavis commented 2 years ago

i think there are actually two separate issues here:

the error message for an unknown class should be better (this issue, addressable with the above comment)
errors in cm files should have location info (a new issue, more involved)

azdavis / millet