M.V. Hutz
15c904ccc9
## Description This PR refactors the lambda calculus reduction engine to use a more efficient LIFO (Last-In-First-Out) stack-based iteration strategy. Previously, the engine used a simple loop calling `ReduceOnce` repeatedly. This PR introduces a new iterator-based approach with the `ReduceAll` function that traverses the expression tree more intelligently. Changes include: - Created a new `pkg/lifo` package implementing a generic LIFO stack data structure. - Added `pkg/lambda/iterator.go` with an `Iterator` type for traversing lambda expressions. - Refactored `pkg/lambda/reduce.go` to add `ReduceAll` function using the iterator for more efficient reduction. - Updated `internal/engine/engine.go` to use `ReduceAll` instead of looping `ReduceOnce`. - Renamed sample test files from `.txt` to `.test` extension. - Fixed `.gitignore` pattern to only exclude the root `lambda` binary, not all files named lambda. - Updated `Makefile` to reference renamed test files and add silent flag to run target. ### Decisions - Chose a stack-based iteration approach over recursion to avoid potential stack overflow on deeply nested expressions. - Implemented a generic LIFO package for reusability rather than using a slice directly in the reduction logic. - Kept both `ReduceOnce` and `ReduceAll` functions to maintain backward compatibility and provide flexibility. ## Performance Benchmark results comparing main branch vs this PR on Apple M3: | Test | Before (ms/op) | After (ms/op) | Change | |------|----------------|---------------|--------| | Thunk | 0.014 | 0.014 | 0.00% | | Fast | 1.29 | 1.20 | **-7.04%** | | Simple | 21.51 | 6.45 | **-70.01%** | | Church | 157.67 | 43.00 | -76.788% | | Saccharine | 185.25 | 178.99 | **-3.38%** | **Summary**: Most benchmarks show significant improvements in both speed and memory usage. The Church benchmark shows a regression that needs investigation. ## Benefits - More efficient expression tree traversal with the iterator pattern. - Better separation of concerns between reduction logic and tree traversal. - Generic LIFO stack can be reused in other parts of the codebase. - Cleaner engine implementation with callback-based step emission. ## Checklist - [x] Code follows conventional commit format. - [x] Branch follows naming convention (`<type>/<description>`). Always use underscores. - [ ] Tests pass (if applicable). - [ ] Documentation updated (if applicable). Reviewed-on: #15 Co-authored-by: M.V. Hutz <git@maximhutz.me> Co-committed-by: M.V. Hutz <git@maximhutz.me>
48 lines
1.4 KiB
Makefile
48 lines
1.4 KiB
Makefile
BINARY_NAME=lambda
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TEST=simple
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.PHONY: help build run profile explain graph docs bench clean
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.DEFAULT_GOAL := help
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.SILENT:
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help:
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echo "Available targets:"
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echo " build - Build the lambda executable"
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echo " run - Build and run the lambda interpreter (use TEST=<name> to specify sample)"
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echo " profile - Build and run with CPU profiling enabled"
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echo " explain - Build and run with explanation mode and profiling"
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echo " graph - Generate and open CPU profile visualization"
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echo " docs - Start local godoc server on port 6060"
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echo " bench - Run benchmarks for all samples"
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echo " clean - Remove all build artifacts"
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build:
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go build -o ${BINARY_NAME} ./cmd/lambda
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chmod +x ${BINARY_NAME}
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run: build
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./${BINARY_NAME} -s -f ./tests/$(TEST).test -o program.out
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profile: build
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./${BINARY_NAME} -p profile/cpu.prof -f ./tests/$(TEST).test -o program.out
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explain: build
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./${BINARY_NAME} -x -p profile/cpu.prof -f ./tests/$(TEST).test -o program.out > explain.out
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graph:
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go tool pprof -raw -output=profile/cpu.raw profile/cpu.prof
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go tool pprof -svg profile/cpu.prof > profile/cpu.svg
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echo ">>> View at 'file://$(PWD)/profile/cpu.svg'"
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docs:
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echo ">>> View at 'http://localhost:6060/pkg/git.maximhutz.com/max/lambda/'"
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go run golang.org/x/tools/cmd/godoc@latest -http=:6060
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bench:
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go test -bench=. -benchtime=10x -cpu=4 ./cmd/lambda
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clean:
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rm -f ${BINARY_NAME}
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rm -f program.out
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rm -rf profile/
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