Some minor touchup to preconditions and fix for minus.

[haz]

Proposed changes

Forgo negating an expression for the ability to subtract two expressions.

Fixes

Fixes #100, but also breaks the use of - as something that negates.

Types of changes

What types of changes does your code introduce? Put an x in the boxes that apply

• [x] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply.

• [x] I have read the CONTRIBUTING doc
• [x] Lint and unit tests pass locally with my changes
• [x] I have added tests that prove my fix is effective or that my feature works

Further comments

More discussion over in #100

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 88.76%. Comparing base (502c7a4) to head (caf21a1). Report is 34 commits behind head on main.

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Additional details and impacted files

[](https://app.codecov.io/gh/AI-Planning/pddl/pull/104?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning) ```diff @@ Coverage Diff @@ ## main #104 +/- ## ========================================== + Coverage 88.35% 88.76% +0.41% ========================================== Files 25 25 Lines 1794 1798 +4 Branches 333 335 +2 ========================================== + Hits 1585 1596 +11 + Misses 149 144 -5 + Partials 60 58 -2 ``` | [Flag](https://app.codecov.io/gh/AI-Planning/pddl/pull/104/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/AI-Planning/pddl/pull/104/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning) | `88.76% <100.00%> (+0.41%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files with missing lines](https://app.codecov.io/gh/AI-Planning/pddl/pull/104?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning) | Coverage Δ | | |---|---|---| | [pddl/parser/domain.py](https://app.codecov.io/gh/AI-Planning/pddl/pull/104?src=pr&el=tree&filepath=pddl%2Fparser%2Fdomain.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning#diff-cGRkbC9wYXJzZXIvZG9tYWluLnB5) | `78.36% <100.00%> (+2.10%)` | :arrow_up: | ... and [1 file with indirect coverage changes](https://app.codecov.io/gh/AI-Planning/pddl/pull/104/indirect-changes?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=AI-Planning)

[haz]

Tests all run green, but marking this as WIP until we resolve the discussion over in #100