Simplify StreamType

eval/builtin-func.go

@@ -26,7 +26,7 @@ var builtinFuncs = map[string]builtinFunc{
 	"printchan": builtinFunc{printchan, [2]StreamType{chanStream, fdStream}},
 	"feedchan":  builtinFunc{feedchan, [2]StreamType{fdStream, chanStream}},
 	"unpack":    builtinFunc{unpack, [2]StreamType{0, chanStream}},
-	"each":      builtinFunc{each, [2]StreamType{chanStream, chanStream}},
+	"each":      builtinFunc{each, [2]StreamType{chanStream, hybridStream}},
 	"cd":        builtinFunc{cd, [2]StreamType{}},
 	"+":         builtinFunc{plus, [2]StreamType{0, chanStream}},
 	"-":         builtinFunc{minus, [2]StreamType{0, chanStream}},

eval/exec.go

@@ -31,36 +31,12 @@ type StreamType byte
 
 // Possible values of StreamType.
 const (
-	unusedStream StreamType = iota
-	fdStream                // Corresponds to port.f.
-	chanStream              // Corresponds to port.ch.
+	unusedStream StreamType = 0
+	fdStream                = 1 << iota // Corresponds to port.f.
+	chanStream                          // Corresponds to port.ch.
+	hybridStream = fdStream | chanStream
 )
 
-// commonType returns a StreamType compatible with both StreamType's. A
-// StreamType is compatible with itself or unusedStream.
-func (typ StreamType) commonType(typ2 StreamType) (StreamType, bool) {
-	switch {
-	case typ == unusedStream, typ == typ2:
-		return typ2, true
-	case typ2 == unusedStream:
-		return typ, true
-	default:
-		return 0, false
-	}
-}
-
-// mayConvey returns whether port may convey a stream of typ.
-func (i *port) mayConvey(typ StreamType) bool {
-	switch typ {
-	case fdStream:
-		return i != nil && i.f != nil
-	case chanStream:
-		return i != nil && i.ch != nil
-	default: // Actually case unusedStream:
-		return true
-	}
-}
-
 // closePorts closes the suitable components of all ports in ev.ports that were
 // marked marked for closing.
 func (ev *Evaluator) closePorts() {