got variable assignment working

main.go

@@ -9,16 +9,32 @@ import (
 
 func main() {
 	mkcmd := func(a lang.Atom, args ...lang.Term) lang.Tuple {
-		return lang.Tuple{a, lang.Tuple{vm.Tuple, lang.Tuple(args)}}
+		if len(args) == 1 {
+			return lang.Tuple{a, args[0]}
+		}
+		return lang.Tuple{a, lang.Tuple(args)}
 	}
 	mkint := func(i string) lang.Tuple {
 		return lang.Tuple{vm.Int, lang.Const(i)}
 	}
 
-	t := mkcmd(vm.Add, mkint("1"),
-		mkcmd(vm.Add, mkint("2"), mkint("3")))
+	//foo := lang.Atom("foo")
+	//tt := []lang.Term{
+	//	mkcmd(vm.Assign, foo, mkint("1")),
+	//	mkcmd(vm.Add, mkcmd(vm.Tuple, mkcmd(vm.Var, foo), mkint("2"))),
+	//}
 
-	mod, err := vm.Build(t)
+	foo := lang.Atom("foo")
+	bar := lang.Atom("bar")
+	baz := lang.Atom("baz")
+	tt := []lang.Term{
+		mkcmd(vm.Assign, foo, mkcmd(vm.Tuple, mkint("1"), mkint("2"))),
+		mkcmd(vm.Assign, bar, mkcmd(vm.Add, mkcmd(vm.Var, foo))),
+		mkcmd(vm.Assign, baz, mkcmd(vm.Add, mkcmd(vm.Var, foo))),
+		mkcmd(vm.Add, mkcmd(vm.Tuple, mkcmd(vm.Var, bar), mkcmd(vm.Var, baz))),
+	}
+
+	mod, err := vm.Build(tt...)
 	if err != nil {
 		panic(err)
 	}

vm/cmds.go

@@ -30,6 +30,7 @@ func (vt valType) eq(vt2 valType) bool {
 
 // primitive valTypes
 var (
+	valTypeVoid = valType{term: lang.Tuple{}, llvm: llvm.VoidType()}
 	valTypeInt  = valType{term: Int, llvm: llvm.Int64Type()}
 )
 
@@ -39,10 +40,7 @@ var (
 type voidIn struct{}
 
 func (voidIn) inType() valType {
-	return valType{
-		term: lang.Tuple{},
-		llvm: llvm.VoidType(),
-	}
+	return valTypeVoid
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -94,8 +92,9 @@ func (to tupOp) build(mod *Module) (llvm.Value, error) {
 	var err error
 	for i := range to.els {
 		if val, err = to.els[i].build(mod); err != nil {
-			str = mod.b.CreateInsertValue(str, val, i, "")
+			return llvm.Value{}, err
 		}
+		str = mod.b.CreateInsertValue(str, val, i, "")
 	}
 	return str, err
 }
@@ -130,6 +129,48 @@ func (teo tupElOp) build(mod *Module) (llvm.Value, error) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
+type assignOp struct {
+	name string
+	op
+}
+
+func (ao assignOp) build(mod *Module) (llvm.Value, error) {
+	v, err := ao.op.build(mod)
+	if err != nil {
+		return llvm.Value{}, err
+	}
+	mod.ctx[ao.name] = builtOp{op: ao.op, v: v}
+	return v, nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+type builtOp struct {
+	op
+	v llvm.Value
+}
+
+func (bo builtOp) build(*Module) (llvm.Value, error) {
+	return bo.v, nil
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
+type varOp struct {
+	op
+	name string
+}
+
+func (vo varOp) build(mod *Module) (llvm.Value, error) {
+	o, err := mod.ctx.get(vo.name)
+	if err != nil {
+		return llvm.Value{}, err
+	}
+	return o.build(mod)
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 type addOp struct {
 	voidIn
 	a, b op
@@ -153,7 +194,7 @@ func (ao addOp) build(mod *Module) (llvm.Value, error) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-func termToOp(t lang.Term) (op, error) {
+func termToOp(ctx varCtx, t lang.Term) (op, error) {
 	aPat := func(a lang.Atom) lang.Tuple {
 		return lang.Tuple{lang.AAtom, a}
 	}
@@ -172,7 +213,7 @@ func termToOp(t lang.Term) (op, error) {
 
 	// for when v is a Tuple argument, convenience function for casting
 	vAsTup := func(n int) ([]op, error) {
-		vop, err := termToOp(v)
+		vop, err := termToOp(ctx, v)
 		if err != nil {
 			return nil, err
 		}
@@ -198,11 +239,37 @@ func termToOp(t lang.Term) (op, error) {
 		tc := tupOp{els: make([]op, len(tup))}
 		var err error
 		for i := range tup {
-			if tc.els[i], err = termToOp(tup[i]); err != nil {
+			if tc.els[i], err = termToOp(ctx, tup[i]); err != nil {
 				return nil, err
 			}
 		}
 		return tc, nil
+	case Assign:
+		if !lang.Match(tPat(aPat(lang.AUnder), lang.TDblUnder), v) {
+			return nil, errors.New("assign requires 2-tuple arg")
+		}
+		tup := v.(lang.Tuple)
+		name := tup[0].String()
+		o, err := termToOp(ctx, tup[1])
+		if err != nil {
+			return nil, err
+		}
+		ao := assignOp{op: o, name: name}
+		ctx[name] = o
+		return ao, nil
+	case Var:
+		if !lang.Match(aPat(lang.AUnder), v) {
+			return nil, errors.New("var requires atom arg")
+		}
+		name := v.(lang.Atom).String()
+		o, err := ctx.get(name)
+		if err != nil {
+			return nil, err
+		}
+		return varOp{op: o, name: name}, nil
+
+	// Add is special in some way, I think it's a function not a compiler op,
+	// not sure yet though
 	case Add:
 		els, err := vAsTup(2)
 		if err != nil {

vm/vm.go

@@ -17,24 +17,37 @@ var (
 	Int   = lang.Atom("int")
 )
 
-// Commands supported by the vm. Each of the types are also commands
+// Ops supported by the vm
 var (
 	Add    = lang.Atom("add")
+	Assign = lang.Atom("assign")
+	Var    = lang.Atom("var")
 )
 
+type varCtx map[string]op
+
+func (c varCtx) get(v string) (op, error) {
+	if o, ok := c[v]; ok {
+		return o, nil
+	}
+	return nil, fmt.Errorf("unknown assigned %q in this context", v)
+}
+
 // Module contains a compiled set of code which can be run, dumped in IR form,
 // or compiled. A Module should be Dispose()'d of once it's no longer being
 // used.
 type Module struct {
 	b      llvm.Builder
 	m      llvm.Module
+	ctx    varCtx
 	mainFn llvm.Value
 }
 
 var initOnce sync.Once
 
-// Build creates a new Module by compiling the given Term as code
-func Build(t lang.Term) (*Module, error) {
+// Build creates a new Module by compiling the given Terms as code
+// TODO only take in a single Term, implement List and use that with a do op
+func Build(tt ...lang.Term) (*Module, error) {
 	initOnce.Do(func() {
 		llvm.LinkInMCJIT()
 		llvm.InitializeNativeTarget()
@@ -43,10 +56,11 @@ func Build(t lang.Term) (*Module, error) {
 	mod := &Module{
 		b:   llvm.NewBuilder(),
 		m:   llvm.NewModule(""),
+		ctx: varCtx{},
 	}
 
 	var err error
-	if mod.mainFn, err = mod.buildFn(t); err != nil {
+	if mod.mainFn, err = mod.buildFn(tt...); err != nil {
 		mod.Dispose()
 		return nil, err
 	}
@@ -75,7 +89,7 @@ func (mod *Module) buildFn(tt ...lang.Term) (llvm.Value, error) {
 	ops := make([]op, len(tt))
 	var err error
 	for i := range tt {
-		if ops[i], err = termToOp(tt[i]); err != nil {
+		if ops[i], err = termToOp(mod.ctx, tt[i]); err != nil {
 			return llvm.Value{}, err
 		}
 	}
@@ -95,7 +109,7 @@ func (mod *Module) buildFn(tt ...lang.Term) (llvm.Value, error) {
 	var out llvm.Value
 	for i := range ops {
 		if out, err = ops[i].build(mod); err != nil {
-			return llvm.Value{}, nil
+			return llvm.Value{}, err
 		}
 	}
 	mod.b.CreateRet(out)