Add (preliminary) support for dicts structure

.github/workflows/go.yml

@@ -16,7 +16,7 @@ jobs:
     - name: Set up Go
       uses: actions/setup-go@v2
       with:
-        go-version: 1.19
+        go-version: 1.23
 
     - name: Build
       run: go build -v ./...

engine/atom.go

@@ -28,6 +28,7 @@ var (
 	atomGreaterThan       = NewAtom(">")
 	atomDot               = NewAtom(".")
 	atomComma             = NewAtom(",")
+	atomDict              = NewAtom("dict")
 	atomBar               = NewAtom("|")
 	atomCut               = NewAtom("!")
 	atomSemiColon         = NewAtom(";")
@@ -66,6 +67,7 @@ var (
 	atomCompound                = NewAtom("compound")
 	atomCreate                  = NewAtom("create")
 	atomDebug                   = NewAtom("debug")
+	atomDictKey                 = NewAtom("dict_key")
 	atomDiscontiguous           = NewAtom("discontiguous")
 	atomDiv                     = NewAtom("div")
 	atomDomainError             = NewAtom("domain_error")

engine/builtin.go

@@ -453,6 +453,11 @@ func renamedCopy(t Term, copied map[termID]Term, env *Env) (Term, error) {
 			}
 			c.args[i] = cp
 		}
+
+		if _, ok := t.(Dict); ok {
+			return &dict{c}, nil
+		}
+
 		return &c, nil
 	default:
 		return t, nil

engine/builtin_test.go

@@ -40,7 +40,7 @@ func TestCall(t *testing.T) {
 	assert.NoError(t, vm.Compile(context.Background(), `
 foo.
 foo(_, _).
-f(g([a, [b, c|X]])).
+f(g([a, [b, c|X], Y{x:5}])).
 `))
 
 	tests := []struct {
@@ -55,14 +55,14 @@ f(g([a, [b, c|X]])).
 		{title: `undefined atom`, goal: NewAtom("bar"), ok: false, err: existenceError(objectTypeProcedure, atomSlash.Apply(NewAtom("bar"), Integer(0)), nil)},
 		{title: `defined atom`, goal: NewAtom("foo"), ok: true},
 		{title: `undefined compound`, goal: NewAtom("bar").Apply(NewVariable(), NewVariable()), ok: false, err: existenceError(objectTypeProcedure, atomSlash.Apply(NewAtom("bar"), Integer(2)), nil)},
-		{title: `defined compound`, goal: NewAtom("foo").Apply(NewVariable(), NewVariable()), ok: true},
+		{title: `defined compound`, goal: NewAtom("foo").Apply(NewVariable(), makeDict(NewVariable())), ok: true},
 		{title: `variable: single predicate`, goal: NewVariable(), ok: false, err: InstantiationError(nil)},
 		{title: `variable: multiple predicates`, goal: atomComma.Apply(atomFail, NewVariable()), ok: false},
 		{title: `not callable: single predicate`, goal: Integer(0), ok: false, err: typeError(validTypeCallable, Integer(0), nil)},
 		{title: `not callable: conjunction`, goal: atomComma.Apply(atomTrue, Integer(0)), ok: false, err: typeError(validTypeCallable, atomComma.Apply(atomTrue, Integer(0)), nil)},
 		{title: `not callable: disjunction`, goal: atomSemiColon.Apply(Integer(1), atomTrue), ok: false, err: typeError(validTypeCallable, atomSemiColon.Apply(Integer(1), atomTrue), nil)},
 
-		{title: `cover all`, goal: atomComma.Apply(atomCut, NewAtom("f").Apply(NewAtom("g").Apply(List(NewAtom("a"), PartialList(NewVariable(), NewAtom("b"), NewAtom("c")))))), ok: true},
+		{title: `cover all`, goal: atomComma.Apply(atomCut, NewAtom("f").Apply(NewAtom("g").Apply(List(NewAtom("a"), PartialList(NewVariable(), NewAtom("b"), NewAtom("c")), makeDict(NewAtom("foo"), NewAtom("x"), Integer(5)))))), ok: true},
 		{title: `out of memory`, goal: NewAtom("foo").Apply(NewVariable(), NewVariable(), NewVariable(), NewVariable(), NewVariable(), NewVariable(), NewVariable(), NewVariable(), NewVariable()), err: resourceError(resourceMemory, nil), mem: 1},
 		{title: `panic`, goal: NewAtom("do_not_call"), err: PanicError{errors.New("told you")}},
 		{title: `panic (lazy)`, goal: NewAtom("lazy_do_not_call"), err: PanicError{errors.New("told you")}},
@@ -583,6 +583,15 @@ func TestTypeCompound(t *testing.T) {
 		assert.True(t, ok)
 	})
 
+	t.Run("dict is compound", func(t *testing.T) {
+		ok, err := TypeCompound(nil, &dict{compound{
+			functor: NewAtom("foo"),
+			args:    []Term{NewAtom("a")},
+		}}, Success, nil).Force(context.Background())
+		assert.NoError(t, err)
+		assert.True(t, ok)
+	})
+
 	t.Run("not compound", func(t *testing.T) {
 		ok, err := TypeCompound(nil, NewAtom("foo"), Success, nil).Force(context.Background())
 		assert.NoError(t, err)

engine/clause.go

@@ -65,16 +65,78 @@
 
 func compileClause(head Term, body Term, env *Env) (clause, error) {
 	var c clause
+	var goals []Term
+
+	head, goals = desugar(head, goals)
+	body, goals = desugar(body, goals)
+
+	if body != nil {
+		goals = append(goals, body)
+	}
+	if len(goals) > 0 {
+		body = seq(atomComma, goals...)
+	}
+
 	c.compileHead(head, env)
+
 	if body != nil {
 		if err := c.compileBody(body, env); err != nil {
 			return c, typeError(validTypeCallable, body, env)
 		}
 	}
-	c.bytecode = append(c.bytecode, instruction{opcode: OpExit})
+
+	c.emit(instruction{opcode: OpExit})
 	return c, nil
 }
 
+func desugar(term Term, acc []Term) (Term, []Term) {
+	switch t := term.(type) {
+	case charList, codeList:
+		return t, acc
+	case list:
+		l := make(list, len(t))
+		for i, e := range t {
+			l[i], acc = desugar(e, acc)
+		}
+		return l, acc
+	case *partial:
+		c, acc := desugar(t.Compound, acc)
+		tail, acc := desugar(*t.tail, acc)
+		return &partial{
+			Compound: c.(Compound),
+			tail:     &tail,
+		}, acc
+	case Compound:
+		if t.Functor() == atomSpecialDot && t.Arity() == 2 {
+			tempV := NewVariable()
+			lhs, acc := desugar(t.Arg(0), acc)
+			rhs, acc := desugar(t.Arg(1), acc)
+
+			return tempV, append(acc, atomDot.Apply(lhs, rhs, tempV))
+		}
+
+		c := compound{
+			functor: t.Functor(),
+			args:    make([]Term, t.Arity()),
+		}
+		for i := 0; i < t.Arity(); i++ {
+			c.args[i], acc = desugar(t.Arg(i), acc)
+		}
+
+		if _, ok := t.(Dict); ok {
+			return &dict{c}, acc
+		}
+
+		return &c, acc
+	default:
+		return t, acc
+	}
+}
+
+func (c *clause) emit(i instruction) {
+	c.bytecode = append(c.bytecode, i)
+}
+
 func (c *clause) compileHead(head Term, env *Env) {
 	switch head := env.Resolve(head).(type) {
 	case Atom:
@@ -88,7 +150,7 @@
 }
 
 func (c *clause) compileBody(body Term, env *Env) error {
-	c.bytecode = append(c.bytecode, instruction{opcode: OpEnter})
+	c.emit(instruction{opcode: OpEnter})
 	iter := seqIterator{Seq: body, Env: env}
 	for iter.Next() {
 		if err := c.compilePred(iter.Current(), env); err != nil {
@@ -107,16 +169,16 @@
 	case Atom:
 		switch p {
 		case atomCut:
-			c.bytecode = append(c.bytecode, instruction{opcode: OpCut})
+			c.emit(instruction{opcode: OpCut})
 			return nil
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpCall, operand: procedureIndicator{name: p, arity: 0}})
+		c.emit(instruction{opcode: OpCall, operand: procedureIndicator{name: p, arity: 0}})
 		return nil
 	case Compound:
 		for i := 0; i < p.Arity(); i++ {
 			c.compileBodyArg(p.Arg(i), env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpCall, operand: procedureIndicator{name: p.Functor(), arity: Integer(p.Arity())}})
+		c.emit(instruction{opcode: OpCall, operand: procedureIndicator{name: p.Functor(), arity: Integer(p.Arity())}})
 		return nil
 	default:
 		return errNotCallable
@@ -126,67 +188,84 @@
 func (c *clause) compileHeadArg(a Term, env *Env) {
 	switch a := env.Resolve(a).(type) {
 	case Variable:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetVar, operand: c.varOffset(a)})
+		c.emit(instruction{opcode: OpGetVar, operand: c.varOffset(a)})
 	case charList, codeList: // Treat them as if they're atomic.
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetConst, operand: a})
+		c.emit(instruction{opcode: OpGetConst, operand: a})
 	case list:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetList, operand: Integer(len(a))})
+		c.emit(instruction{opcode: OpGetList, operand: Integer(len(a))})
 		for _, arg := range a {
 			c.compileHeadArg(arg, env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
 	case *partial:
 		prefix := a.Compound.(list)
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetPartial, operand: Integer(len(prefix))})
+		c.emit(instruction{opcode: OpGetPartial, operand: Integer(len(prefix))})
 		c.compileHeadArg(*a.tail, env)
 		for _, arg := range prefix {
 			c.compileHeadArg(arg, env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
 	case Compound:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetFunctor, operand: procedureIndicator{name: a.Functor(), arity: Integer(a.Arity())}})
+		switch a.(type) {
+		case Dict:
+			c.emit(instruction{opcode: OpGetDict, operand: Integer(a.Arity())})
+		default:
+			c.emit(instruction{opcode: OpGetFunctor, operand: procedureIndicator{name: a.Functor(), arity: Integer(a.Arity())}})
+		}
+
 		for i := 0; i < a.Arity(); i++ {
 			c.compileHeadArg(a.Arg(i), env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
 	default:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpGetConst, operand: a})
+		c.emit(instruction{opcode: OpGetConst, operand: a})
 	}
 }
 
 func (c *clause) compileBodyArg(a Term, env *Env) {
 	switch a := env.Resolve(a).(type) {
 	case Variable:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutVar, operand: c.varOffset(a)})
+		c.emit(instruction{opcode: OpPutVar, operand: c.varOffset(a)})
 	case charList, codeList: // Treat them as if they're atomic.
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutConst, operand: a})
+		c.emit(instruction{opcode: OpPutConst, operand: a})
 	case list:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutList, operand: Integer(len(a))})
+		c.emit(instruction{opcode: OpPutList, operand: Integer(len(a))})
 		for _, arg := range a {
 			c.compileBodyArg(arg, env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
+	case Dict:
+		c.emit(instruction{opcode: OpPutDict, operand: Integer(a.Arity())})
+		for i := 0; i < a.Arity(); i++ {
+			c.compileBodyArg(a.Arg(i), env)
+		}
+		c.emit(instruction{opcode: OpPop})
 	case *partial:
 		var l int
 		iter := ListIterator{List: a.Compound}
 		for iter.Next() {
 			l++
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutPartial, operand: Integer(l)})
+		c.emit(instruction{opcode: OpPutPartial, operand: Integer(l)})
 		c.compileBodyArg(*a.tail, env)
 		iter = ListIterator{List: a.Compound}
 		for iter.Next() {
 			c.compileBodyArg(iter.Current(), env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
 	case Compound:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutFunctor, operand: procedureIndicator{name: a.Functor(), arity: Integer(a.Arity())}})
+		switch a.(type) {
+		case Dict:
+			c.emit(instruction{opcode: OpPutDict, operand: Integer(a.Arity())})
+		default:
+			c.emit(instruction{opcode: OpPutFunctor, operand: procedureIndicator{name: a.Functor(), arity: Integer(a.Arity())}})
+		}
 		for i := 0; i < a.Arity(); i++ {
 			c.compileBodyArg(a.Arg(i), env)
 		}
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPop})
+		c.emit(instruction{opcode: OpPop})
 	default:
-		c.bytecode = append(c.bytecode, instruction{opcode: OpPutConst, operand: a})
+		c.emit(instruction{opcode: OpPutConst, operand: a})
 	}
 }