Merge branch 'master' into remove-cruft-core

Author: MaximilianAlgehed

.github/workflows/haskell-ci.yml

@@ -11,6 +11,12 @@ on:
       - 'master'
   schedule:
     - cron: 0 0 * * *
+  workflow_dispatch:
+    inputs:
+      nightly:
+        description: Run with the same settings as a nightly build
+        type: boolean
+        default: false
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
@@ -29,6 +35,14 @@ jobs:
     runs-on: ${{ matrix.os }}
 
     steps:
+      - name: Set NIGHTLY environment variable if the job was triggered by the scheduler
+        if: "${{ github.event_name == 'schedule'
+              || contains(github.event.pull_request.title, 'nightly')
+              || contains(github.event.pull_request.title, 'NIGHTLY')
+              || github.event_name == 'workflow_dispatch' && github.event.inputs.nightly }}"
+        run: |
+          echo "NIGHTLY=true" >> $GITHUB_ENV
+
       - uses: actions/checkout@v4
       - uses: haskell-actions/setup@v2
         with:
@@ -50,40 +64,48 @@ jobs:
     name: Stack
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v4
+      - name: Set NIGHTLY environment variable if the job was triggered by the scheduler
+        if: "${{ github.event_name == 'schedule'
+              || contains(github.event.pull_request.title, 'nightly')
+              || contains(github.event.pull_request.title, 'NIGHTLY')
+              || github.event_name == 'workflow_dispatch' && github.event.inputs.nightly }}"
+        run: |
+          echo "NIGHTLY=true" >> $GITHUB_ENV
+
+      - uses: actions/checkout@v4
 
-    - uses: haskell-actions/setup@v2
-      id: setup-haskell-stack
-      name: Setup Haskell
-      with:
-        enable-stack: true
-        stack-version: latest
-        ghc-version: 9.6.7
+      - uses: haskell-actions/setup@v2
+        id: setup-haskell-stack
+        name: Setup Haskell
+        with:
+          enable-stack: true
+          stack-version: latest
+          ghc-version: 9.6.7
 
-    - name: Cache
-      id: cache
-      uses: actions/cache@v4
-      with:
-        path: |
-          ${{ steps.setup-haskell-stack.outputs.stack-root }}
-          .stack-work
-        key: ${{ runner.os }}-stack-${{ github.sha }}
-        restore-keys: ${{ runner.os }}-stack
+      - name: Cache
+        id: cache
+        uses: actions/cache@v4
+        with:
+          path: |
+            ${{ steps.setup-haskell-stack.outputs.stack-root }}
+            .stack-work
+          key: ${{ runner.os }}-stack-${{ github.sha }}
+          restore-keys: ${{ runner.os }}-stack
 
-    - name: Test
-      run: stack test --coverage --flag constrained-generators:dev
+      - name: Test
+        run: stack test --coverage --flag constrained-generators:dev
 
-    - uses: actions/cache/save@v4
-      with:
-        path: |
-          ${{ steps.setup-haskell-stack.outputs.stack-root }}
-          .stack-work
-        key: ${{ runner.os }}-stack-${{ github.sha }}
+      - uses: actions/cache/save@v4
+        with:
+          path: |
+            ${{ steps.setup-haskell-stack.outputs.stack-root }}
+            .stack-work
+          key: ${{ runner.os }}-stack-${{ github.sha }}
 
-    - name: Upload coverage report
-      env:
-        COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
-      run: |
-        [ -n "${COVERALLS_REPO_TOKEN}" ]
-        curl -L https://github.com/rubik/stack-hpc-coveralls/releases/download/v0.0.7.0/shc-Linux-X64.tar.bz2 | tar xj shc
-        ./shc --repo-token="$COVERALLS_REPO_TOKEN" --partial-coverage --fetch-coverage combined all
+      - name: Upload coverage report
+        env:
+          COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
+        run: |
+          [ -n "${COVERALLS_REPO_TOKEN}" ]
+          curl -L https://github.com/rubik/stack-hpc-coveralls/releases/download/v0.0.7.0/shc-Linux-X64.tar.bz2 | tar xj shc
+          ./shc --repo-token="$COVERALLS_REPO_TOKEN" --partial-coverage --fetch-coverage combined all

examples/Constrained/Examples/BinTree.hs

@@ -76,6 +76,8 @@ instance HasSpec a => HasSpec (BinTree a) where
       : (BinNode left a <$> shrinkWithTypeSpec s right)
       ++ ((\l -> BinNode l a right) <$> shrinkWithTypeSpec s left)
 
+  fixupWithTypeSpec _ _ = Nothing
+
   cardinalTypeSpec _ = mempty
 
   toPreds t (BinTreeSpec msz s) =

src/Constrained/Base.hs

@@ -488,6 +488,12 @@ class
   -- | Shrink an `a` with the aide of a `TypeSpec`
   shrinkWithTypeSpec :: TypeSpec a -> a -> [a]
 
+  -- | Try to make an `a` conform to `TypeSpec` with minimal changes. When
+  -- `fixupWithSpec ts a` returns `Just a'`, it should be the case that
+  -- `conformsTo a' ts`. There are no constraints in the `Nothing` case. A
+  -- non-trivial implementation of this function is important for shrinking.
+  fixupWithTypeSpec :: TypeSpec a -> a -> Maybe a
+
   -- | Convert a spec to predicates:
   -- The key property here is:
   --   ∀ a. a `conformsTo` spec == a `conformsTo` constrained (\t -> toPreds t spec)
@@ -598,6 +604,13 @@ class
     [a]
   shrinkWithTypeSpec spec a = map fromSimpleRep $ shrinkWithTypeSpec spec (toSimpleRep a)
 
+  default fixupWithTypeSpec ::
+    GenericallyInstantiated a =>
+    TypeSpec a ->
+    a ->
+    Maybe a
+  fixupWithTypeSpec spec a = fromSimpleRep <$> fixupWithTypeSpec spec (toSimpleRep a)
+
   default cardinalTypeSpec ::
     GenericallyInstantiated a =>
     TypeSpec a ->
@@ -618,6 +631,7 @@ instance HasSpec Bool where
   cardinalTypeSpec _ = equalSpec 2
   cardinalTrueSpec = equalSpec 2
   shrinkWithTypeSpec _ = shrink
+  fixupWithTypeSpec _ = Just
   conformsTo _ _ = True
   toPreds _ _ = TruePred
 
@@ -627,6 +641,7 @@ instance HasSpec () where
   combineSpec _ _ = typeSpec ()
   _ `conformsTo` _ = True
   shrinkWithTypeSpec _ _ = []
+  fixupWithTypeSpec _ _ = pure ()
   genFromTypeSpec _ = pure ()
   toPreds _ _ = TruePred
   cardinalTypeSpec _ = MemberSpec (pure 1)

src/Constrained/Conformance.hs

@@ -14,6 +14,7 @@ module Constrained.Conformance (
   conformsToSpec,
   conformsToSpecE,
   satisfies,
+  checkPredE,
   checkPredsE,
 ) where
 

src/Constrained/Generation.hs

@@ -25,6 +25,7 @@ module Constrained.Generation (
   genFromSpecT,
   genFromSpecWithSeed,
   shrinkWithSpec,
+  fixupWithSpec,
   simplifySpec,
 
   -- ** Debugging
@@ -155,15 +156,71 @@ shrinkWithSpec (simplifySpec -> spec) a = filter (`conformsToSpec` spec) $ case
   ExplainSpec _ s -> shrinkWithSpec s a
   -- TODO: filter on can't if we have a known to be sound shrinker
   TypeSpec s _ -> shrinkWithTypeSpec s a
-  -- TODO: The better way of doing this is to compute the dependency graph,
-  -- shrink one variable at a time, and fixup the rest of the variables
-  SuspendedSpec {} -> shr a
+  SuspendedSpec x p -> shrinkFromPreds p x a ++ shr a
   MemberSpec {} -> shr a
   TrueSpec -> shr a
   ErrorSpec {} -> []
   where
     shr = shrinkWithTypeSpec (emptySpec @a)
 
+shrinkFromPreds :: HasSpec a => Pred -> Var a -> a -> [a]
+shrinkFromPreds p
+  | Result plan <- prepareLinearization p = \x a -> listFromGE $ do
+      -- NOTE: we do this to e.g. guard against bad construction functions in Exists
+      case checkPredE (Env.singleton x a) (NE.fromList []) p of
+        Nothing -> pure ()
+        Just err -> explainNE err $ fatalError "Trying to shrink a bad value, don't do that!"
+      -- Get an `env` for the original value
+      initialEnv <- envFromPred (Env.singleton x a) p
+      return
+        [ a'
+        | -- Shrink the initialEnv
+        env' <- shrinkEnvFromPlan initialEnv plan
+        , -- Get the value of the constrained variable `x` in the shrunk env
+        Just a' <- [Env.lookup env' x]
+        , -- NOTE: this is necessary because it's possible that changing
+        -- a particular value in the env during shrinking might not result
+        -- in the value of `x` changing and there is no better way to know than
+        -- to do this.
+        a' /= a
+        ]
+  | otherwise = error "Bad pred"
+
+-- Start with a valid Env for the plan and try to shrink it
+shrinkEnvFromPlan :: Env -> SolverPlan -> [Env]
+shrinkEnvFromPlan initialEnv SolverPlan {..} = go mempty solverPlan
+  where
+    go :: Env -> [SolverStage] -> [Env]
+    go _ [] = [] -- In this case we decided to keep every variable the same so nothing to return
+    go env ((unsafeSubstStage env -> SolverStage {..}) : plan) = do
+      Just a <- [Env.lookup initialEnv stageVar]
+      -- Two cases:
+      --  - either we shrink this value and try to fixup every value later on in the plan or
+      [ fixedEnv
+        | a' <- shrinkWithSpec stageSpec a
+        , let env' = Env.extend stageVar a' env
+        , Just fixedEnv <- [fixupPlan env' plan]
+        ]
+        --  - we keep this value the way it is and try to shrink some later value
+        ++ go (Env.extend stageVar a env) plan
+
+    -- Fix the rest of the plan given an environment `env` for the plan so far
+    fixupPlan :: Env -> [SolverStage] -> Maybe Env
+    fixupPlan env [] = pure env
+    fixupPlan env ((unsafeSubstStage env -> SolverStage {..}) : plan) =
+      case Env.lookup (env <> initialEnv) stageVar >>= fixupWithSpec stageSpec of
+        Nothing -> Nothing
+        Just a -> fixupPlan (Env.extend stageVar a env) plan
+
+-- Try to fix a value w.r.t a specification
+fixupWithSpec :: forall a. HasSpec a => Specification a -> a -> Maybe a
+fixupWithSpec spec a
+  | a `conformsToSpec` spec = Just a
+  | otherwise = case spec of
+      MemberSpec (a' :| _) -> Just a'
+      TypeSpec ts _ -> fixupWithTypeSpec ts a >>= \ a' -> a' <$  guard (conformsToSpec a' spec)
+      _ -> listToMaybe $ filter (`conformsToSpec` spec) (shrinkWithSpec TrueSpec a)
+
 -- Debugging --------------------------------------------------------------
 
 -- | A version of `genFromSpecT` that runs in the IO monad. Good for debugging.
@@ -197,6 +254,10 @@ prettyPlan (simplifySpec -> spec)
 
 -- ---------------------- Building a plan -----------------------------------
 
+unsafeSubstStage :: Env -> SolverStage -> SolverStage
+unsafeSubstStage env (SolverStage y ps spec relevant) =
+  normalizeSolverStage $ SolverStage y (substPred env <$> ps) spec relevant
+
 substStage :: HasSpec a => Set Name -> Var a -> a -> SolverStage -> SolverStage
 substStage rel' x val (SolverStage y ps spec relevant) =
   normalizeSolverStage $ SolverStage y (substPred env <$> ps) spec relevant'
@@ -1105,6 +1166,9 @@ instance (HasSpec a, HasSpec b, KnownNat (CountCases b)) => HasSpec (Sum a b) wh
   shrinkWithTypeSpec (SumSpec _ sa _) (SumLeft a) = SumLeft <$> shrinkWithSpec sa a
   shrinkWithTypeSpec (SumSpec _ _ sb) (SumRight b) = SumRight <$> shrinkWithSpec sb b
 
+  fixupWithTypeSpec (SumSpec _ sa _) (SumLeft a) = SumLeft <$> fixupWithSpec sa a
+  fixupWithTypeSpec (SumSpec _ _ sb) (SumRight b) = SumRight <$> fixupWithSpec sb b
+
   toPreds ct (SumSpec h sa sb) =
     Case
       ct