Use outer product semantics for indexing.

eval/compile.go

@@ -617,22 +617,32 @@ func (cp *compiler) indexing(n *parse.Indexing) ValuesOp {
 
 	headOp := cp.primary(n.Head)
 	indexOps := cp.arrays(n.Indicies)
-	p := n.Begin()
+	// p := n.Begin()
 	indexPoses := make([]int, len(n.Indicies))
 	for i, index := range n.Indicies {
 		indexPoses[i] = index.Begin()
 	}
 
 	return func(ec *EvalCtx) []Value {
-		v := ec.must(headOp(ec), "the indexing value", p).mustOne()
-		for i, indexOp := range indexOps {
-			index := ec.must(indexOp(ec), "the index", p).mustOne()
-			v = evalIndex(ec, v, index, p, indexPoses[i])
+		vs := headOp(ec)
+		for _, indexOp := range indexOps {
+			index := indexOp(ec)
+			vs = outerProduct(vs, index, func(l, r Value) Value {
+				return mustIndexer(l).Index(r)
+			})
 		}
-		return []Value{v}
+		return vs
 	}
 }
 
+func mustIndexer(v Value) Indexer {
+	indexer, ok := v.(Indexer)
+	if !ok {
+		throw(fmt.Errorf("%s value cannot be indexed", v.Kind()))
+	}
+	return indexer
+}
+
 func literalValues(v ...Value) ValuesOp {
 	return func(e *EvalCtx) []Value {
 		return v

eval/exec.go

@@ -191,8 +191,7 @@ type IndexerCaller struct {
 func (ic IndexerCaller) Call(ec *EvalCtx, argVals []Value) {
 	var v Value = ic.Indexer
 	for _, idx := range argVals {
-		// XXX the positions are obviously wrong.
-		v = evalIndex(ec, v, idx, 0, 0)
+		v = mustIndexer(v).Index(idx)
 	}
 	ec.ports[1].Chan <- v
 }

eval/value.go

@@ -442,20 +442,6 @@ func stringToSegments(s string) []glob.Segment {
 	return segs
 }
 
-func evalIndex(ec *EvalCtx, l, r Value, lp, rp int) Value {
-	left, ok := l.(Indexer)
-	if !ok {
-		ec.errorf(lp, "%s value cannot be indexing", l.Kind())
-	}
-
-	right, ok := r.(String)
-	if !ok {
-		ec.errorf(rp, "%s invalid cannot be used as index", r.Kind())
-	}
-
-	return left.Index(right)
-}
-
 // FromJSONInterface converts a interface{} that results from json.Unmarshal to
 // a Value.
 func FromJSONInterface(v interface{}) Value {

parse/parse.go

@@ -376,7 +376,10 @@ func (ctrl *Control) parse(ps *parser, leader string) {
 		parseSpaces(ctrl, ps)
 		ctrl.setIterator(parsePrimary(ps))
 		parseSpaces(ctrl, ps)
-		if consumeLeader() != "in" {
+		if ps.findPossibleLeader() == "in" {
+			ps.advance(len("in"))
+			addSep(ctrl, ps)
+		} else {
 			ps.error(errShouldBeIn)
 		}
 		ctrl.setArray(parseArray(ps))