feat: some basic commands

cmd/lambda/lambda.go

@@ -1,8 +1,10 @@
 package main
 
 import (
+	"fmt"
 	"os"
 
+	"git.maximhutz.com/max/lambda/internal/config"
 	"github.com/spf13/cobra"
 )
 
@@ -11,14 +13,74 @@ func Lambda() *cobra.Command {
 		Use:   "lambda",
 		Short: "Lambda calculus interpreter",
 		Long:  "A lambda calculus interpreter supporting multiple representations.",
-		RunE: func(cmd *cobra.Command, _ []string) error {
-			return cmd.Help()
+		RunE: func(cmd *cobra.Command, args []string) error {
+			// Legacy behavior when no subcommand is given.
+			options, err := config.FromArgs()
+			if err != nil {
+				return err
+			}
+
+			logger := options.GetLogger()
+			logger.Info("using program arguments", "args", os.Args)
+			logger.Info("parsed CLI options", "options", options)
+
+			r := GetRegistry()
+
+			// Get input.
+			input, err := options.Source.Extract()
+			if err != nil {
+				return err
+			}
+
+			// Parse code into syntax tree.
+			repr, err := r.Unmarshal(input, "saccharine")
+			if err != nil {
+				return err
+			}
+			logger.Info("parsed syntax tree", "tree", repr)
+
+			// Compile expression to lambda calculus.
+			compiled, err := r.ConvertTo(repr, "lambda")
+			if err != nil {
+				return err
+			}
+			logger.Info("compiled λ expression", "tree", compiled)
+
+			// Create reducer with the compiled expression.
+			engine, err := r.GetDefaultEngine("lambda")
+			if err != nil {
+				return err
+			}
+
+			process := engine.Load()
+			err = process.Set(compiled)
+			if err != nil {
+				return err
+			}
+
+			// Run reduction.
+			for process.Step(1) {
+			}
+
+			// Return the final reduced result.
+			result, err := process.Get()
+			if err != nil {
+				return err
+			}
+
+			output, err := r.Marshal(result)
+			if err != nil {
+				return err
+			}
+
+			return options.Destination.Write(output)
 		},
 	}
 
+	cmd.PersistentFlags().BoolP("verbose", "v", false, "Enable verbose output")
+
 	cmd.AddCommand(LambdaConvert())
 	cmd.AddCommand(LambdaEngine())
-	cmd.AddCommand(LambdaReduce())
 
 	return cmd
 }
@@ -26,6 +88,7 @@ func Lambda() *cobra.Command {
 func main() {
 	lambda := Lambda()
 	if err := lambda.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
 		os.Exit(1)
 	}
 }

cmd/lambda/lambda_convert.go

@@ -6,15 +6,17 @@ import (
 	"path/filepath"
 	"strings"
 
+	"git.maximhutz.com/max/lambda/internal/cli"
 	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
 )
 
 // inferReprFromPath returns the repr type based on file extension.
 func inferReprFromPath(path string) (string, error) {
 	switch ext := strings.ToLower(filepath.Ext(path)); ext {
-	case ".lambda", ".lam", ".lc":
+	case ".lam", ".lambda":
 		return "lambda", nil
-	case ".saccharine", ".sch":
+	case ".sac", ".saccharine":
 		return "saccharine", nil
 	default:
 		return "", fmt.Errorf("unknown file extension '%s'", ext)
@@ -22,33 +24,23 @@ func inferReprFromPath(path string) (string, error) {
 }
 
 func LambdaConvert() *cobra.Command {
-	var inputReprFlag, outputReprFlag string
-
 	cmd := &cobra.Command{
-		Use:          "convert <input-file> <output-file>",
-		Short:        "Convert between lambda calculus representations",
-		SilenceUsage: true,
+		Use:   "convert <input> <output>",
+		Short: "Convert between lambda calculus representations",
+		Args:  cobra.ExactArgs(2),
 		RunE: func(cmd *cobra.Command, args []string) error {
-			if len(args) != 2 {
-				return cmd.Help()
+			inputPath := args[0]
+			outputPath := args[1]
+
+			// Infer repr types from extensions.
+			inputRepr, err := inferReprFromPath(inputPath)
+			if err != nil {
+				return fmt.Errorf("input file: %w", err)
 			}
 
-			var err error
-			inputPath, outputPath := args[0], args[1]
-
-			// Use flag if provided, otherwise infer from extension.
-			inputRepr := inputReprFlag
-			if inputRepr == "" {
-				if inputRepr, err = inferReprFromPath(inputPath); err != nil {
-					return fmt.Errorf("input file: %w", err)
-				}
-			}
-
-			outputRepr := outputReprFlag
-			if outputRepr == "" {
-				if outputRepr, err = inferReprFromPath(outputPath); err != nil {
-					return fmt.Errorf("output file: %w", err)
-				}
+			outputRepr, err := inferReprFromPath(outputPath)
+			if err != nil {
+				return fmt.Errorf("output file: %w", err)
 			}
 
 			// Read input file.
@@ -65,16 +57,29 @@ func LambdaConvert() *cobra.Command {
 				return fmt.Errorf("parsing input: %w", err)
 			}
 
+			if viper.GetBool("verbose") {
+				fmt.Fprintf(os.Stderr, "Parsed %s from %s\n", inputRepr, inputPath)
+			}
+
 			// Convert to output repr if different.
-			result, err := r.ConvertTo(repr, outputRepr)
-			if err != nil {
-				return fmt.Errorf("converting %s to %s: %w", inputRepr, outputRepr, err)
+			var result cli.Repr
+			if inputRepr != outputRepr {
+				result, err = r.ConvertTo(repr, outputRepr)
+				if err != nil {
+					return fmt.Errorf("converting %s to %s: %w", inputRepr, outputRepr, err)
+				}
+
+				if viper.GetBool("verbose") {
+					fmt.Fprintf(os.Stderr, "Converted to %s\n", outputRepr)
+				}
+			} else {
+				result = repr
 			}
 
 			// Marshal output.
 			output, err := r.Marshal(result)
 			if err != nil {
-				return fmt.Errorf("unmarshaling output: %w", err)
+				return fmt.Errorf("marshaling output: %w", err)
 			}
 
 			// Write output file.
@@ -83,12 +88,13 @@ func LambdaConvert() *cobra.Command {
 				return fmt.Errorf("writing output file: %w", err)
 			}
 
+			if viper.GetBool("verbose") {
+				fmt.Fprintf(os.Stderr, "Wrote %s to %s\n", outputRepr, outputPath)
+			}
+
 			return nil
 		},
 	}
 
-	cmd.Flags().StringVar(&inputReprFlag, "from", "", "Input representation (inferred from extension if unset)")
-	cmd.Flags().StringVar(&outputReprFlag, "to", "", "Output representation (inferred from extension if unset)")
-
 	return cmd
 }

cmd/lambda/lambda_reduce.go

@@ -1,109 +0,0 @@
-package main
-
-import (
-	"fmt"
-
-	"github.com/spf13/cobra"
-
-	"git.maximhutz.com/max/lambda/internal/cli"
-	"git.maximhutz.com/max/lambda/internal/config"
-)
-
-func LambdaReduce() *cobra.Command {
-	var inputReprFlag string
-	var engineFlag string
-
-	cmd := &cobra.Command{
-		Use:          "reduce <input-file>",
-		Short:        "Reduce a lambda calculus expression",
-		SilenceUsage: true,
-		Aliases:      []string{"run"},
-		RunE: func(cmd *cobra.Command, args []string) error {
-			var err error
-			if len(args) != 1 {
-				return cmd.Help()
-			}
-
-			inputPath := args[0]
-
-			// Get input source.
-			var source config.Source
-			if inputPath == "-" {
-				source = config.StdinSource{}
-			} else {
-				source = config.FileSource{Path: inputPath}
-			}
-
-			destination := config.StdoutDestination{}
-
-			r := GetRegistry()
-
-			// Get input.
-			input, err := source.Extract()
-			if err != nil {
-				return err
-			}
-
-			// Use flag if provided, otherwise infer from extension.
-			inputRepr := inputReprFlag
-			if inputRepr == "" {
-				if inputRepr, err = inferReprFromPath(inputPath); err != nil {
-					return fmt.Errorf("input file: %w", err)
-				}
-			}
-
-			// Find engine.
-			var engine cli.Engine
-			if engineFlag == "" {
-				if engine, err = r.GetDefaultEngine(inputRepr); err != nil {
-					return err
-				}
-			} else {
-				if engine, err = r.GetEngine(engineFlag); err != nil {
-					return err
-				}
-			}
-
-			// Parse code into syntax tree.
-			repr, err := r.Unmarshal(input, inputRepr)
-			if err != nil {
-				return err
-			}
-
-			// Compile expression to lambda calculus.
-			compiled, err := r.ConvertTo(repr, "lambda")
-			if err != nil {
-				return err
-			}
-
-			// Create process.
-			process := engine.Load()
-			err = process.Set(compiled)
-			if err != nil {
-				return err
-			}
-
-			// Run reduction.
-			for process.Step(1) {
-			}
-
-			// Return the final reduced result.
-			result, err := process.Get()
-			if err != nil {
-				return err
-			}
-
-			output, err := r.Marshal(result)
-			if err != nil {
-				return err
-			}
-
-			return destination.Write(output)
-		},
-	}
-
-	cmd.Flags().StringVar(&inputReprFlag, "from", "", "Input representation (inferred from extension if unset)")
-	cmd.Flags().StringVarP(&engineFlag, "engine", "e", "", "Reduction engine (inferred from '--input' if unset)")
-
-	return cmd
-}

go.mod

@@ -2,9 +2,25 @@ module git.maximhutz.com/max/lambda
 
 go 1.25.5
 
-require github.com/spf13/cobra v1.10.2
+require github.com/stretchr/testify v1.11.1
 
 require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/fsnotify/fsnotify v1.9.0 // indirect
+	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/sagikazarmark/locafero v0.11.0 // indirect
+	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
+	github.com/spf13/afero v1.15.0 // indirect
+	github.com/spf13/cast v1.10.0 // indirect
+	github.com/spf13/cobra v1.10.2 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
+	github.com/spf13/viper v1.21.0 // indirect
+	github.com/subosito/gotenv v1.6.0 // indirect
+	go.yaml.in/yaml/v3 v3.0.4 // indirect
+	golang.org/x/sys v0.29.0 // indirect
+	golang.org/x/text v0.28.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -1,11 +1,42 @@
 github.com/cpuguy83/go-md2man/v2 v2.0.6/go.mod h1:oOW0eioCTA6cOiMLiUPZOpcVxMig6NIQQ7OS05n1F4g=
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
+github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
+github.com/go-viper/mapstructure/v2 v2.4.0 h1:EBsztssimR/CONLSZZ04E8qAkxNYq4Qp9LvH92wZUgs=
+github.com/go-viper/mapstructure/v2 v2.4.0/go.mod h1:oJDH3BJKyqBA2TXFhDsKDGDTlndYOZ6rGS0BRZIxGhM=
 github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
 github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
+github.com/pelletier/go-toml/v2 v2.2.4/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/sagikazarmark/locafero v0.11.0 h1:1iurJgmM9G3PA/I+wWYIOw/5SyBtxapeHDcg+AAIFXc=
+github.com/sagikazarmark/locafero v0.11.0/go.mod h1:nVIGvgyzw595SUSUE6tvCp3YYTeHs15MvlmU87WwIik=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 h1:+jumHNA0Wrelhe64i8F6HNlS8pkoyMv5sreGx2Ry5Rw=
+github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8/go.mod h1:3n1Cwaq1E1/1lhQhtRK2ts/ZwZEhjcQeJQ1RuC6Q/8U=
+github.com/spf13/afero v1.15.0 h1:b/YBCLWAJdFWJTN9cLhiXXcD7mzKn9Dm86dNnfyQw1I=
+github.com/spf13/afero v1.15.0/go.mod h1:NC2ByUVxtQs4b3sIUphxK0NioZnmxgyCrfzeuq8lxMg=
+github.com/spf13/cast v1.10.0 h1:h2x0u2shc1QuLHfxi+cTJvs30+ZAHOGRic8uyGTDWxY=
+github.com/spf13/cast v1.10.0/go.mod h1:jNfB8QC9IA6ZuY2ZjDp0KtFO2LZZlg4S/7bzP6qqeHo=
 github.com/spf13/cobra v1.10.2 h1:DMTTonx5m65Ic0GOoRY2c16WCbHxOOw6xxezuLaBpcU=
 github.com/spf13/cobra v1.10.2/go.mod h1:7C1pvHqHw5A4vrJfjNwvOdzYu0Gml16OCs2GRiTUUS4=
 github.com/spf13/pflag v1.0.9/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/spf13/pflag v1.0.10 h1:4EBh2KAYBwaONj6b2Ye1GiHfwjqyROoF4RwYO+vPwFk=
 github.com/spf13/pflag v1.0.10/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+github.com/spf13/viper v1.21.0 h1:x5S+0EU27Lbphp4UKm1C+1oQO+rKx36vfCoaVebLFSU=
+github.com/spf13/viper v1.21.0/go.mod h1:P0lhsswPGWD/1lZJ9ny3fYnVqxiegrlNrEmgLjbTCAY=
+github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
+github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
+github.com/subosito/gotenv v1.6.0 h1:9NlTDc1FTs4qu0DDq7AEtTPNw6SVm7uBMsUCUjABIf8=
+github.com/subosito/gotenv v1.6.0/go.mod h1:Dk4QP5c2W3ibzajGcXpNraDfq2IrhjMIvMSWPKKo0FU=
+go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
 go.yaml.in/yaml/v3 v3.0.4/go.mod h1:DhzuOOF2ATzADvBadXxruRBLzYTpT36CKvDb3+aBEFg=
+golang.org/x/sys v0.29.0 h1:TPYlXGxvx1MGTn2GiZDhnjPA9wZzZeGKHHmKhHYvgaU=
+golang.org/x/sys v0.29.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.28.0 h1:rhazDwis8INMIwQ4tpjLDzUhx6RlXqZNPEM0huQojng=
+golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/cli/conversion.go

@@ -21,7 +21,7 @@ type forwardCodec[T, U any] struct {
 func (c forwardCodec[T, U]) Run(r Repr) (Repr, error) {
 	t, ok := r.Data().(T)
 	if !ok {
-		return nil, fmt.Errorf("could not parse '%v' as '%s'", t, c.inType)
+		return nil, fmt.Errorf("could not parse '%v' as '%s'", t, c.outType)
 	}
 
 	u, err := c.codec.Encode(t)
@@ -29,7 +29,7 @@ func (c forwardCodec[T, U]) Run(r Repr) (Repr, error) {
 		return nil, err
 	}
 
-	return NewRepr(c.outType, u), nil
+	return NewRepr(c.inType, u), nil
 }
 
 func (c forwardCodec[T, U]) InType() string { return c.inType }
@@ -44,7 +44,7 @@ type backwardCodec[T, U any] struct {
 func (c backwardCodec[T, U]) Run(r Repr) (Repr, error) {
 	u, ok := r.Data().(U)
 	if !ok {
-		return nil, fmt.Errorf("could not parse '%v' as '%s'", r, c.outType)
+		return nil, fmt.Errorf("could not parse '%v' as '%s'", r, c.inType)
 	}
 
 	t, err := c.codec.Decode(u)
@@ -52,7 +52,7 @@ func (c backwardCodec[T, U]) Run(r Repr) (Repr, error) {
 		return nil, err
 	}
 
-	return NewRepr(c.inType, t), nil
+	return NewRepr(c.outType, t), nil
 }
 
 func (c backwardCodec[T, U]) InType() string { return c.outType }

internal/cli/marshaler.go

@@ -2,7 +2,6 @@ package cli
 
 import (
 	"fmt"
-	"reflect"
 
 	"git.maximhutz.com/max/lambda/pkg/codec"
 )
@@ -30,9 +29,7 @@ func (c convertedMarshaler[T]) Decode(s string) (Repr, error) {
 func (c convertedMarshaler[T]) Encode(r Repr) (string, error) {
 	t, ok := r.Data().(T)
 	if !ok {
-		dataType := reflect.TypeOf(r.Data())
-		allowedType := reflect.TypeFor[T]()
-		return "", fmt.Errorf("marshaler for '%s' cannot parse '%s'", allowedType, dataType)
+		return "", fmt.Errorf("could not parse '%v' as 'string'", t)
 	}
 
 	return c.codec.Encode(t)

internal/registry_new/conversion.go

@@ -1,9 +0,0 @@
-package registrynew
-
-// Conversion
-type Conversion interface {
-	InRepr() string
-	OutRepr() string
-
-	Run(Expr) (Expr, error)
-}

internal/registry_new/engine.go

@@ -1,12 +0,0 @@
-package registrynew
-
-type Process interface {
-	Get() (Expr, error)
-	Step(int) bool
-}
-
-type Engine interface {
-	Load(Expr) Process
-	Name() string
-	InRepr() string
-}

internal/registry_new/expr.go

@@ -1,7 +0,0 @@
-package registrynew
-
-type Expr interface {
-	Repr() string
-
-	Data() any
-}

internal/registry_new/marshaler.go

@@ -1,5 +0,0 @@
-package registrynew
-
-type Marshaler interface {
-	InType() string
-}

internal/registry_new/registry.go

@@ -1,10 +0,0 @@
-package registrynew
-
-import "iter"
-
-type Registry interface {
-	ListEngines() iter.Seq[string]
-	GetEngine(name string) (Engine, error)
-
-	ListReprs() iter.Seq[string]
-}

internal/registry_new/repr.go

@@ -1,4 +0,0 @@
-package registrynew
-
-type Repr interface {
-}