Started working on map functions

cmdlang/builtins.go

@@ -52,16 +52,26 @@ func toUpperBuiltin(ctx context.Context, inStream stream, args invocationArgs) (
 	// Handle args
 	return mapFilterStream{
 		in: inStream,
-		mapFn: func(x object) (object, bool) {
+		mapFn: func(x object) (object, bool, error) {
 			s, ok := x.(strObject)
 			if !ok {
-				return nil, false
+				return nil, false, nil
 			}
-			return strObject(strings.ToUpper(string(s))), true
+			return strObject(strings.ToUpper(string(s))), true, nil
 		},
 	}, nil
 }
 
+func concatBuiltin(ctx context.Context, args invocationArgs) (object, error) {
+	var sb strings.Builder
+
+	for _, a := range args.args {
+		sb.WriteString(a.String())
+	}
+
+	return strObject(sb.String()), nil
+}
+
 func catBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 	if err := args.expectArgn(1); err != nil {
 		return nil, err
@@ -88,6 +98,30 @@ func callBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 	return inv.invoke(ctx, args.shift(1))
 }
 
+func mapBuiltin(ctx context.Context, inStream stream, args invocationArgs) (object, error) {
+	args, strm, err := args.streamableSource(inStream)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := args.expectArgn(1); err != nil {
+		return nil, err
+	}
+
+	inv, ok := args.args[0].(invokable)
+	if !ok {
+		return nil, errors.New("expected invokable")
+	}
+
+	return mapFilterStream{
+		in: strm,
+		mapFn: func(x object) (object, bool, error) {
+			y, err := inv.invoke(ctx, args.fork(nil, []object{x}))
+			return y, true, err
+		},
+	}, nil
+}
+
 type fileLinesStream struct {
 	filename string
 	f        *os.File

cmdlang/eval.go

@@ -3,9 +3,7 @@ package cmdlang
 import (
 	"context"
 	"errors"
-	"fmt"
 	"strconv"
-	"strings"
 )
 
 type evaluator struct {
@@ -218,17 +216,15 @@ func (e evaluator) evalSub(ctx context.Context, ec *evalCtx, n *astPipeline) (ob
 
 	switch v := pipelineRes.(type) {
 	case stream:
-		// TODO: use proper lists here, not a string join
+		list := listObject{}
-		sb := strings.Builder{}
 		if err := forEach(v, func(o object, _ int) error {
-			// TODO: use o.String()
+			list = append(list, o)
-			sb.WriteString(fmt.Sprint(o))
 			return nil
 		}); err != nil {
 			return nil, err
 		}
 
-		return strObject(sb.String()), nil
+		return list, nil
 	}
 	return pipelineRes, nil
 }

cmdlang/inst.go

@@ -30,9 +30,13 @@ func New(opts ...InstOption) *Inst {
 	rootEC.addCmd("echo", invokableFunc(echoBuiltin))
 	rootEC.addCmd("set", invokableFunc(setBuiltin))
 	rootEC.addCmd("toUpper", invokableStreamFunc(toUpperBuiltin))
-	rootEC.addCmd("cat", invokableFunc(catBuiltin))
+	//rootEC.addCmd("cat", invokableFunc(catBuiltin))
 	rootEC.addCmd("call", invokableFunc(callBuiltin))
 
+	rootEC.addCmd("map", invokableStreamFunc(mapBuiltin))
+
+	rootEC.addCmd("cat", invokableFunc(concatBuiltin))
+
 	rootEC.addMacro("if", macroFunc(ifBuiltin))
 	rootEC.addMacro("foreach", macroFunc(foreachBuiltin))
 	rootEC.addMacro("proc", macroFunc(procBuiltin))

cmdlang/objs.go

@@ -172,6 +172,25 @@ type invocationArgs struct {
 	kwargs        map[string]*listObject
 }
 
+// streamableSource takes a stream.  If the stream is set, the inStream and invocation arguments are consumed as is.
+// If not, then the first argument is consumed and returned as a stream.
+func (ia invocationArgs) streamableSource(inStream stream) (invocationArgs, stream, error) {
+	if inStream != nil {
+		return ia, inStream, nil
+	}
+
+	if len(ia.args) < 1 {
+		return ia, nil, errors.New("expected at least 1 argument")
+	}
+
+	switch v := ia.args[0].(type) {
+	case listObject:
+		return ia.shift(1), &listIterStream{list: v}, nil
+	}
+
+	return ia, nil, errors.New("expected arg 0 to be streamable")
+}
+
 func (ia invocationArgs) expectArgn(x int) error {
 	if len(ia.args) < x {
 		return errors.New("expected at least " + strconv.Itoa(x) + " args")
@@ -190,6 +209,16 @@ func (ia invocationArgs) stringArg(i int) (string, error) {
 	return s.String(), nil
 }
 
+func (ia invocationArgs) fork(currentStr stream, args []object) invocationArgs {
+	return invocationArgs{
+		inst:          ia.inst,
+		ec:            ia.ec,
+		currentStream: currentStr,
+		args:          args,
+		kwargs:        make(map[string]*listObject),
+	}
+}
+
 func (ia invocationArgs) shift(i int) invocationArgs {
 	return invocationArgs{
 		inst:          ia.inst,

cmdlang/streams.go

@@ -116,7 +116,7 @@ func (s *listIterStream) close() error { return nil }
 
 type mapFilterStream struct {
 	in    stream
-	mapFn func(x object) (object, bool)
+	mapFn func(x object) (object, bool, error)
 }
 
 func (ms mapFilterStream) String() string {
@@ -134,8 +134,10 @@ func (ms mapFilterStream) next() (object, error) {
 			return nil, err
 		}
 
-		t, ok := ms.mapFn(u)
+		t, ok, err := ms.mapFn(u)
-		if ok {
+		if err != nil {
+			return nil, err
+		} else if ok {
 			return t, nil
 		}
 	}