feat: statistics flag, commented some more

cmd/lambda/lambda.go

@@ -6,7 +6,7 @@ import (
 
 	"git.maximhutz.com/max/lambda/internal/cli"
 	"git.maximhutz.com/max/lambda/internal/config"
-	"git.maximhutz.com/max/lambda/internal/executer"
+	"git.maximhutz.com/max/lambda/internal/engine"
 	"git.maximhutz.com/max/lambda/internal/explanation"
 	"git.maximhutz.com/max/lambda/internal/performance"
 	"git.maximhutz.com/max/lambda/internal/statistics"
@@ -15,8 +15,8 @@ import (
 	"git.maximhutz.com/max/lambda/pkg/saccharine"
 )
 
-// Run main application.
 func main() {
+	// Parse CLI arguments.
 	options, err := config.FromArgs()
 	cli.HandleError(err)
 
@@ -24,7 +24,8 @@ func main() {
 	logger.Info("using program arguments", "args", os.Args)
 	logger.Info("parsed CLI options", "options", options)
 
-	input, err := options.Source.Pull()
+	// Get input.
+	input, err := options.Source.Extract()
 	cli.HandleError(err)
 
 	// Parse tokens.
@@ -35,33 +36,46 @@ func main() {
 	// Turn tokens into syntax tree.
 	expression, err := saccharine.Parse(tokens)
 	cli.HandleError(err)
-	if options.Verbose {
-		logger.Info("parsed syntax tree", "tree", saccharine.Stringify(expression))
-	}
+	logger.Info("parsed syntax tree", "tree", saccharine.Stringify(expression))
 
+	// Compile expression to lambda calculus.
 	compiled := convert.SaccharineToLambda(expression)
-	if options.Verbose {
-		logger.Info("compiled lambda expression", "tree", lambda.Stringify(compiled))
-	}
+	logger.Info("compiled lambda expression", "tree", lambda.Stringify(compiled))
 
-	process := executer.New(options, &compiled)
+	// Create reduction engine.
+	process := engine.New(options, &compiled)
+
+	// If the user selected to track CPU performance, attach a profiler to the
+	// process.
 	if options.Profile != "" {
 		profiler := performance.Track(options.Profile)
 		process.On("start", profiler.Start)
 		process.On("end", profiler.End)
 	}
 
+	// If the user selected to produce a step-by-step explanation, attach an
+	// observer here.
 	if options.Explanation {
 		explanation.Track(process)
 	}
 
-	statistics := statistics.Track()
-	process.On("start", statistics.Start)
-	process.On("step", statistics.Step)
-	process.On("end", statistics.End)
+	// If the user opted to track statistics, attach a tracker here, too.
+	if options.Statistics {
+		statistics := statistics.Track()
+		process.On("start", statistics.Start)
+		process.On("step", statistics.Step)
+		process.On("end", statistics.End)
+	}
+
+	// If the user selected for verbose debug logs, attach a reduction tracker.
+	if options.Verbose {
+		process.On("step", func() {
+			logger.Info("reduction", "tree", lambda.Stringify(compiled))
+		})
+	}
 
 	process.Run()
 
+	// Return the final reduced result.
 	fmt.Println(lambda.Stringify(compiled))
-	fmt.Fprint(os.Stderr, statistics.Results.String())
 }