Add a port to Go

README.adoc

@@ -6,8 +6,9 @@ ell
 a programming language implementable with as little code as possible while
 still being reasonably comfortable to use.
 
-This package is an implementation of said language, meant to be self-contained,
-portable and reusable.  Performance is specifically not an intent.
+This package contains two implementations of said language--one in C and
+another in Go--which are meant to be self-contained, portable and reusable.
+Performance is specifically not an intent.
 
 The project is currently in a "proof of concept" stage with many useful data
 operations missing but I believe it won't be a problem to implement them as

cmd/interpreter/main.go

@@ -0,0 +1,63 @@
+//
+// Copyright (c) 2018, Přemysl Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+// Program interpreter is a basic ell interpreter.
+package main
+
+import (
+	"fmt"
+	"io/ioutil"
+	"os"
+
+	"janouch.name/ell/ell"
+)
+
+func main() {
+	var script []byte
+	var err error
+
+	if len(os.Args) < 2 {
+		script, err = ioutil.ReadAll(os.Stdin)
+	} else {
+		script, err = ioutil.ReadFile(os.Args[1])
+	}
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+
+	L := ell.New()
+	if !ell.StdInitialize(L) {
+		fmt.Printf("runtime library initialization failed: %s\n", L.Error)
+	}
+
+	program, err := ell.NewParser(script).Run()
+	if err != nil {
+		fmt.Printf("%s: %s\n", "parse error", err)
+		os.Exit(1)
+	}
+
+	var args *ell.V
+	tail := &args
+	for i := 2; i < len(os.Args); i++ {
+		*tail = ell.NewString([]byte(os.Args[i]))
+		tail = &(*tail).Next
+	}
+
+	var result *ell.V
+	if !L.EvalBlock(program, args, &result) {
+		fmt.Printf("%s: %s\n", "runtime error", L.Error)
+	}
+}

cmd/repl/main.go

@@ -0,0 +1,91 @@
+//
+// Copyright (c) 2018, Přemysl Janouch <p@janouch.name>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+//
+
+// Program repl is an interactive ell interpreter.
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	// This library is rather simplistic but it's going to serve us fine.
+	"github.com/peterh/liner"
+
+	"janouch.name/ell/ell"
+)
+
+func run(L *ell.Ell, program *ell.V) {
+	var result *ell.V
+	if !L.EvalBlock(program, nil, &result) {
+		fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "runtime error", L.Error)
+		L.Error = ""
+	} else {
+		ell.PrintSeq(os.Stdout, result)
+		os.Stdout.WriteString("\n")
+	}
+}
+
+func complete(L *ell.Ell, line string) (res []string) {
+	// This never actually completes anything, just shows the options,
+	// we'd have to figure out the longest common prefix.
+	res = append(res, line)
+
+	line = strings.ToLower(line)
+	for v := L.Globals; v != nil; v = v.Next {
+		name := string(v.Head.String)
+		if strings.HasPrefix(strings.ToLower(name), line) {
+			res = append(res, name)
+		}
+	}
+	for name := range L.Native {
+		if strings.HasPrefix(strings.ToLower(name), line) {
+			res = append(res, name)
+		}
+	}
+	return
+}
+
+func main() {
+	L := ell.New()
+	if !ell.StdInitialize(L) {
+		fmt.Printf("runtime library initialization failed: %s\n", L.Error)
+	}
+
+	line := liner.NewLiner()
+	line.SetCompleter(func(line string) []string { return complete(L, line) })
+	line.SetMultiLineMode(true)
+	line.SetTabCompletionStyle(liner.TabPrints)
+
+	for {
+		script, err := line.Prompt("> ")
+		if err == nil {
+			line.AppendHistory(script)
+
+			p := ell.NewParser([]byte(script))
+			if program, err := p.Run(); err != nil {
+				fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "parse error", err)
+			} else {
+				run(L, program)
+			}
+		} else if err == liner.ErrPromptAborted || err == io.EOF {
+			break
+		} else {
+			fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "error", err)
+		}
+	}
+	os.Stdout.WriteString("\n")
+}