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Initial refactor - much better types (#9)
* Initial refactor - much better types + Use types which are way clearer + Some docs + Use lens where they make things easier + New types required quite a significant factor of the codebase + Cleanup + Further refactoring/polishing + I want type names to reflect those typically used when talking about simplex methods + But first, I need to learn what the actual terms are + I'd also like to simplify a lot of these functions + The refactor has made it easier for me to think about these functions, which makes it easier to simplify them * Run formatter * `FeasibleSystem` instances * Re-add stack * (wip) fix pivoting issues * Switch CI to stack * Use stack to build haddocks * Run formatter * Matrix test windows and macos * Remove ghc 8.10 from CI * Make CI fail when tests fail * Run formatter * Fix broken tests + test10 was broken due to an LLM sneakily adding extra constraints and changing objective + testQuickCheck1/2 were broken because the constraints were built using `Map.fromList` with duplicate keys + only one of the key values were used, others were ignored * polishing * Lens getters -> RecordDot getters * Add logging, improve docs, more tests, handle edge cases + Control.Monad.Logger used for logging + Documented various functions + Handled some edge cases which shouldn't be possible (and log warnings/errors when we reach these edge cases) * fixme * Improve logging * Fourmolu upgrade: limit lines to 120 chars * Upgrade fourmolu action, specify fourmolu version * Bump package version * Bump lts * some helper functions * Rename Linaer.Simplex.Simplex to Linear.Simplex.Solver.TwoPhase + I like this name better + Allows for alternative solvers * Fix caching + I was using the cabal plan as a key, now I use stack files/cabal generated files * Update lts * Diagnose caching issues * Try fixing caching * Remove windows from CI + Don't want to spend effor fixing windows caching * Update workflow step labels * Update stack yaml lock * Add windows + caching to ci * Save .stack-work for windows too * Only save when cache is not hit * Update ChangeLog * Update copyright dates
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‎.github/workflows/haskell.yml‎

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steps:
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- uses: actions/checkout@v3
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- uses: haskell-actions/run-fourmolu@v7
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- uses: haskell-actions/run-fourmolu@v9
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with:
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version: "0.14.0.0"
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build:
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name: GHC ${{ matrix.ghc-version }} on ${{ matrix.os }}
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runs-on: ${{ matrix.os }}
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strategy:
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fail-fast: false
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matrix:
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os: [ubuntu-latest]
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ghc-version: ['9.6', '9.4', '9.2', '9.0', '8.10']
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include:
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- os: windows-latest
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ghc-version: '9.6'
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- os: macos-latest
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ghc-version: '9.6'
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os: [windows-latest, macos-latest, ubuntu-latest]
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ghc-version: ['9.6', '9.4', '9.2', '9.0']
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steps:
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- uses: actions/checkout@v3
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id: setup
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with:
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ghc-version: ${{ matrix.ghc-version }}
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# Defaults, added for clarity:
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cabal-version: 'latest'
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cabal-update: true
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enable-stack: true
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- name: Installed minor versions of GHC and Cabal
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- name: Installed minor versions of GHC, Cabal, and Stack
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shell: bash
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run: |
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GHC_VERSION=$(ghc --numeric-version)
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CABAL_VERSION=$(cabal --numeric-version)
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STACK_VERSION=$(stack --numeric-version)
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echo "GHC_VERSION=${GHC_VERSION}" >> "${GITHUB_ENV}"
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echo "CABAL_VERSION=${CABAL_VERSION}" >> "${GITHUB_ENV}"
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echo "STACK_VERSION=${STACK_VERSION}" >> "${GITHUB_ENV}"
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- name: Configure the build
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run: |
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cabal configure --enable-tests --enable-benchmarks --disable-documentation
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cabal build --dry-run
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# cabal configure --enable-tests --enable-benchmarks --disable-documentation
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# cabal build --dry-run
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stack build --test --bench --no-haddock --dry-run
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# The last step generates dist-newstyle/cache/plan.json for the cache key.
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- name: Restore cached dependencies
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- name: Restore .stack-work cache
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uses: actions/cache/restore@v3
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id: cache-restore-stack-work
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with:
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path: .stack-work
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key: ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-work-${{ hashFiles('stack.yaml') }}-${{ hashFiles('package.yaml') }}-${{ hashFiles('**/*.hs') }}
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restore-keys: |
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${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-work-
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- name: Restore ~/.stack cache (Unix)
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uses: actions/cache/restore@v3
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id: cache-restore-stack-global-unix
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if: runner.os == 'Linux' || runner.os == 'macOS'
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with:
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path: ~/.stack
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key: ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-global-${{ hashFiles('stack.yaml') }}-${{ hashFiles('package.yaml') }}
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restore-keys: |
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${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-global-
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- name: Restore %APPDATA%\stack, %LOCALAPPDATA%\Programs\stack cache (Windows)
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uses: actions/cache/restore@v3
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id: cache
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id: cache-restore-stack-global-windows
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if: runner.os == 'Windows'
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with:
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path: ${{ steps.setup.outputs.cabal-store }}
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key: ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-cabal-${{ env.CABAL_VERSION }}-plan-${{ hashFiles('**/plan.json') }}
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path: |
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~\AppData\Roaming\stack
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~\AppData\Local\Programs\stack
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key: ${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-global-${{ hashFiles('stack.yaml') }}-${{ hashFiles('package.yaml') }}
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restore-keys: |
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${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-cabal-${{ env.CABAL_VERSION }}-
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${{ runner.os }}-ghc-${{ env.GHC_VERSION }}-stack-${{ env.STACK_VERSION }}-stack-global-
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- name: Build dependencies
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run: stack build --only-dependencies
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- name: Install dependencies
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run: cabal build all --only-dependencies
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- name: Build the package
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run: stack build
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# Cache dependencies already here, so that we do not have to rebuild them should the subsequent steps fail.
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- name: Save cached dependencies
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- name: Save .stack-work cache
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uses: actions/cache/save@v3
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# Caches are immutable, trying to save with the same key would error.
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if: ${{ !steps.cache.outputs.cache-hit
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|| steps.cache.outputs.cache-primary-key != steps.cache.outputs.cache-matched-key }}
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id: cache-save-stack-work
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if: steps.cache-restore-stack-work.outputs.cache-hit != 'true'
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with:
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path: ${{ steps.setup.outputs.cabal-store }}
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key: ${{ steps.cache.outputs.cache-primary-key }}
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- name: Build
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run: cabal build all
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path: .stack-work
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key: ${{ steps.cache-restore-stack-work.outputs.cache-primary-key }}
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- name: Save %APPDATA%\stack, %LOCALAPPDATA%\Programs\stack cache (Windows)
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uses: actions/cache/save@v3
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if: runner.os == 'Windows'
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&& steps.cache-restore-stack-global-windows.outputs.cache-hit != 'true'
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with:
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path: |
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~\AppData\Roaming\stack
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~\AppData\Local\Programs\stack
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key: ${{ steps.cache-restore-stack-global-windows.outputs.cache-primary-key }}
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- name: Save ~/.stack cache (Unix)
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uses: actions/cache/save@v3
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id: cache-save-stack-global
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if: (runner.os == 'Linux' || runner.os == 'macOS')
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&& steps.cache-restore-stack-global-unix.outputs.cache-hit != 'true'
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with:
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path: ~/.stack
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key: ${{ steps.cache-restore-stack-global-unix.outputs.cache-primary-key }}
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- name: Run tests
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run: cabal test all
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run: stack test
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- name: Check cabal file
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run: cabal check
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- name: Build documentation
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run: cabal haddock all
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run: stack haddock

‎ChangeLog.md‎

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## Unreleased changes
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## [v0.2.0.0](https://github.com/rasheedja/LPPaver/tree/v0.2.0.0)
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- Setup CI
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- Use fourmolu formatter
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- Switch to Cabal
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- Add better types
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- Use lens
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- Use RecordDot syntax
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- Add logging
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- Improve Docs
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- More Tests
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- Bump Stackage LTS
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- Rename Linear.Simplex.Simplex -> Linear.Simplex.TwoPhase.Simplex
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## [v0.1.0.0](https://github.com/rasheedja/LPPaver/tree/v0.1.0.0)
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‎LICENSE‎

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Copyright Junaid Rasheed (c) 2020-2022
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Copyright Junaid Rasheed (c) 2020-2023
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All rights reserved.
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‎README.md‎

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## Quick Overview
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The `Linear.Simplex.Simplex` module contain both phases of the simplex method.
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The `Linear.Simplex.Solver.TwoPhase` module contain both phases of the two-phase simplex method.
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### Phase One
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```haskell
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data PolyConstraint =
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LEQ VarConstMap Rational |
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GEQ VarConstMap Rational |
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EQ VarConstMap Rational deriving (Show, Eq);
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LEQ Vars Rational |
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GEQ Vars Rational |
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EQ Vars Rational deriving (Show, Eq);
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```
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And `VarConstMap` is defined as:
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And `Vars` is defined as:
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```haskell
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type VarConstMap = [(Integer, Rational)]
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type Vars = [(Integer, Rational)]
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```
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A `VarConstMap` is treated as a list of `Integer` variables mapped to their `Rational` coefficients, with an implicit `+` between each element in the list.
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A `Vars` is treated as a list of `Integer` variables mapped to their `Rational` coefficients, with an implicit `+` between each element in the list.
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For example: `[(1, 2), (2, (-3)), (1, 3)]` is equivalent to `(2x1 + (-3x2) + 3x1)`.
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And a `PolyConstraint` is an inequality/equality where the LHS is a `VarConstMap` and the RHS is a `Rational`.
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And a `PolyConstraint` is an inequality/equality where the LHS is a `Vars` and the RHS is a `Rational`.
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For example: `LEQ [(1, 2), (2, (-3)), (1, 3)] 60` is equivalent to `(2x1 + (-3x2) + 3x1) <= 60`.
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Passing a `[PolyConstraint]` to `findFeasibleSolution` will return a feasible solution if it exists as well as a list of slack variables, artificial variables, and a variable that can be safely used to represent the objective for phase two.
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`Nothing` is returned if the given `[PolyConstraint]` is infeasible.
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The feasible system is returned as the type `DictionaryForm`:
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```haskell
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type DictionaryForm = [(Integer, VarConstMap)]
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type DictionaryForm = [(Integer, Vars)]
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```
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`DictionaryForm` can be thought of as a list of equations, where the `Integer` represents a basic variable on the LHS that is equal to the RHS represented as a `VarConstMap`. In this `VarConstMap`, the `Integer` -1 is used internally to represent a `Rational` number.
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`DictionaryForm` can be thought of as a list of equations, where the `Integer` represents a basic variable on the LHS that is equal to the RHS represented as a `Vars`. In this `Vars`, the `Integer` -1 is used internally to represent a `Rational` number.
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### Phase Two
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`optimizeFeasibleSystem` performs phase two of the simplex method, and has the type:
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```haskell
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data ObjectiveFunction = Max VarConstMap | Min VarConstMap deriving (Show, Eq)
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data ObjectiveFunction = Max Vars | Min Vars deriving (Show, Eq)
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optimizeFeasibleSystem :: ObjectiveFunction -> DictionaryForm -> [Integer] -> [Integer] -> Integer -> Maybe (Integer, [(Integer, Rational)])
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```
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We first pass an `ObjectiveFunction`.
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Then we give a feasible system in `DictionaryForm`, a list of slack variables, a list of artificial variables, and a variable to represent the objective.
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`optimizeFeasibleSystem` Maximizes/Minimizes the linear equation represented as a `VarConstMap` in the given `ObjectiveFunction`.
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`optimizeFeasibleSystem` Maximizes/Minimizes the linear equation represented as a `Vars` in the given `ObjectiveFunction`.
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The first item of the returned pair is the `Integer` variable representing the objective.
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The second item is a list of `Integer` variables mapped to their optimized values.
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If a variable is not in this list, the variable is equal to 0.
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## Usage notes
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You must only use positive `Integer` variables in a `VarConstMap`.
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You must only use positive `Integer` variables in a `Vars`.
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This implementation assumes that the user only provides positive `Integer` variables; the `Integer` -1, for example, is sometimes used to represent a `Rational` number.
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## Example

‎fourmolu.yaml‎

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indentation: 2
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column-limit: none
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column-limit: 120
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function-arrows: trailing
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comma-style: leading
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import-export-style: diff-friendly
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import-export-style: leading
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indent-wheres: true
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record-brace-space: true
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newlines-between-decls: 1
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haddock-style: multi-line
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haddock-style-module:
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let-style: auto
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in-style: right-align
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haddock-style: single-line
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haddock-style-module: single-line
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let-style: inline
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in-style: left-align
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single-constraint-parens: always
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unicode: never
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respectful: true

‎package.yaml‎

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name: simplex-method
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version: 0.2.0.0
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github: "rasheedja/simplex-method"
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license: BSD3
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author: "Junaid Rasheed"
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maintainer: "[email protected]"
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copyright: "BSD-3"
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extra-source-files:
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- README.md
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- ChangeLog.md
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# Metadata used when publishing your package
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synopsis: Implementation of the two-phase simplex method in exact rational arithmetic
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category: Math, Maths, Mathematics, Optimisation, Optimization, Linear Programming
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# To avoid duplicated efforts in documentation and dealing with the
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# complications of embedding Haddock markup inside cabal files, it is
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# common to point users to the README.md file.
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description: Please see the README on GitHub at <https://github.com/rasheedja/simplex-method#readme>
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dependencies:
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- base >= 4.14 && < 5
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- containers >= 0.6.5.1 && < 0.7
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- generic-lens >= 2.2.0 && < 2.3
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- lens >= 5.2.2 && < 5.3
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- monad-logger >= 0.3.40 && < 0.4
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- text >= 2.0.2 && < 2.1
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- time
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default-extensions:
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DataKinds
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DeriveFunctor
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DeriveGeneric
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DisambiguateRecordFields
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DuplicateRecordFields
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FlexibleContexts
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LambdaCase
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OverloadedLabels
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OverloadedRecordDot
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OverloadedStrings
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RecordWildCards
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TemplateHaskell
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TupleSections
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TypeApplications
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NamedFieldPuns
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library:
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source-dirs: src
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tests:
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simplex-haskell-test:
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main: Spec.hs
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source-dirs: test
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dependencies:
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- simplex-method

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