49 lines
1.8 KiB
Markdown
49 lines
1.8 KiB
Markdown
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# CLAUDE.md
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This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
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## Build Commands
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```bash
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cabal build # Build the project
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cabal test # Run all tests
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cabal repl # Start interactive REPL
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```
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To run a single test file or specific test:
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```bash
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cabal test --test-option=--match="/DatalogParser/"
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```
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## Architecture
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This is an experimental Datalog implementation in Haskell with the following components:
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### Parsing Layer (`src/Datalog/DatalogParser.hs`)
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Megaparsec-based parser that converts Datalog text into an AST:
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- `Term` - Variables (`Var`), symbols (`Sym`), numbers (`Num`)
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- `Literal` - Predicate with arguments, optionally negated
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- `Statement` - Fact, Rule (with `Head` and body literals), or Query
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- Entry points: `parseDatalog`, `parseDatalogFile`
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### Evaluation Engine (`src/Datalog/NaiveDatabase.hs`)
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Naive evaluation database storing relations and rules:
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- `NaiveDatabase` - Contains `relations` map and `constants` set (Herbrand universe)
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- `Relation` - Name, arity, tuples (facts), and associated rules
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- `RelationRule` - Head variables and body constraints
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- Key functions: `withFacts`, `withFactsAndRules` for building databases
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- Query evaluation is not yet implemented
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### Data Flow
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1. Text parsed into `Statement` (Fact/Rule/Query)
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2. Facts populate relations with tuples; rules encode derivation logic via `RuleContext` and `BodyConstraint`
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3. Variables are indexed during rule processing for efficient constraint matching
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### Other Modules
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- `SimpleParser` / `ArithmeticParser` - Experimental arithmetic expression parsers
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- `Ologs` - Categorical data structures (dots and arcs representing objects and morphisms)
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## Development Environment
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Nix support via `shell.nix` provides HLS, cabal-install, and Hoogle. Use `direnv allow` for automatic environment loading.
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