C: add const specifiers where appropriate

As a hint whether values are eaten.

README.adoc

@@ -59,7 +59,7 @@ When evaluating a command, the first argument is typically a string with its
 name and it is resolved as if `set` was called on it.  Lists are left for
 execution as they are.
 
-The last expression in a block is the return value.
+The last expression in a block is the block's return value.
 
 Special Forms
 -------------
@@ -172,13 +172,16 @@ Install development packages for GNU Readline to get a REPL for toying around:
  $ make repl
  $ ./repl
 
+The Go port can be built using standard Go tools and behaves the same.
+
 Possible Ways of Complicating
 -----------------------------
  * `local [_a _b _rest] @args` would elegantly solve the problem of varargs,
    that is, unpack a list when names are list, and make the last element a list
    when there are more arguments than names
- * reference counting: currently all values are always copied as needed, which
-   is good enough for all imaginable use cases, simpler and less error-prone
+ * reference counting: in the C version, currently all values are always copied
+   as needed, which is good enough for all imaginable use cases, simpler and
+   less error-prone
 
 Contributing and Support
 ------------------------

cmd/interpreter/main.go

@@ -49,15 +49,11 @@ func main() {
 		os.Exit(1)
 	}
 
-	var args *ell.V
-	tail := &args
+	var args []ell.V
 	for i := 2; i < len(os.Args); i++ {
-		*tail = ell.NewString([]byte(os.Args[i]))
-		tail = &(*tail).Next
+		args = append(args, *ell.NewString(os.Args[i]))
 	}
-
-	var result *ell.V
-	if !L.EvalBlock(program, args, &result) {
+	if _, ok := L.EvalBlock(program, args); !ok {
 		fmt.Printf("%s: %s\n", "runtime error", L.Error)
 	}
 }

cmd/repl/main.go

@@ -28,9 +28,8 @@ import (
 	"janouch.name/ell/ell"
 )
 
-func run(L *ell.Ell, program *ell.V) {
-	var result *ell.V
-	if !L.EvalBlock(program, nil, &result) {
+func run(L *ell.Ell, program []ell.V) {
+	if result, ok := L.EvalBlock(program, nil); !ok {
 		fmt.Printf("\x1b[31m%s: %s\x1b[0m\n", "runtime error", L.Error)
 		L.Error = ""
 	} else {
@@ -39,21 +38,23 @@ func run(L *ell.Ell, program *ell.V) {
 	}
 }
 
-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)
+func complete(L *ell.Ell, line string, pos int) (
+	head string, completions []string, tail string) {
+	tail = string([]rune(line)[pos:])
 
-	line = strings.ToLower(line)
-	for v := L.Globals; v != nil; v = v.Next {
-		name := string(v.Head.String)
+	lastSpace := strings.LastIndexAny(string([]rune(line)[:pos]), " ()[]{};\n")
+	if lastSpace > -1 {
+		head, line = line[:lastSpace+1], line[lastSpace+1:]
+	}
+
+	for name := range L.Globals {
 		if strings.HasPrefix(strings.ToLower(name), line) {
-			res = append(res, name)
+			completions = append(completions, name)
 		}
 	}
 	for name := range L.Native {
 		if strings.HasPrefix(strings.ToLower(name), line) {
-			res = append(res, name)
+			completions = append(completions, name)
 		}
 	}
 	return
@@ -66,7 +67,10 @@ func main() {
 	}
 
 	line := liner.NewLiner()
-	line.SetCompleter(func(line string) []string { return complete(L, line) })
+	line.SetWordCompleter(func(line string, pos int) (
+		string, []string, string) {
+		return complete(L, line, pos)
+	})
 	line.SetMultiLineMode(true)
 	line.SetTabCompletionStyle(liner.TabPrints)
 

ell.c

@@ -793,12 +793,14 @@ ell_can_modify_error (struct ell *ell) {
 	return !ell->memory_failure && ell->error[0] != '_';
 }
 
-static bool ell_eval_statement (struct ell *, struct ell_v *, struct ell_v **);
+static bool ell_eval_statement
+	(struct ell *, const struct ell_v *, struct ell_v **);
 static bool ell_eval_block
-	(struct ell *, struct ell_v *, struct ell_v *, struct ell_v **);
+	(struct ell *, const struct ell_v *, struct ell_v *, struct ell_v **);
 
 static bool
-ell_eval_args (struct ell *ell, struct ell_v *args, struct ell_v **result) {
+ell_eval_args (struct ell *ell,
+	const struct ell_v *args, struct ell_v **result) {
 	size_t i = 0;
 	struct ell_v *res = NULL, **out = &res;
 	for (; args; args = args->next) {
@@ -828,7 +830,7 @@ error:
 }
 
 static bool
-ell_eval_native (struct ell *ell, const char *name, struct ell_v *args,
+ell_eval_native (struct ell *ell, const char *name, const struct ell_v *args,
 	struct ell_v **result) {
 	struct ell_native_fn *fn = ell_native_find (ell, name);
 	if (!fn)
@@ -844,8 +846,8 @@ ell_eval_native (struct ell *ell, const char *name, struct ell_v *args,
 }
 
 static bool
-ell_eval_resolved (struct ell *ell, struct ell_v *body, struct ell_v *args,
-	struct ell_v **result) {
+ell_eval_resolved (struct ell *ell,
+	const struct ell_v *body, const struct ell_v *args, struct ell_v **result) {
 	// Resolving names recursively could be pretty fatal, let's not do that
 	if (body->type == ELL_STRING)
 		return ell_check (ell, (*result = ell_clone (body)));
@@ -855,13 +857,16 @@ ell_eval_resolved (struct ell *ell, struct ell_v *body, struct ell_v *args,
 }
 
 static bool
-ell_eval_value (struct ell *ell, struct ell_v *body, struct ell_v **result) {
-	struct ell_v *args = body->next;
+ell_eval_value (struct ell *ell, const struct ell_v *body,
+	struct ell_v **result) {
+	const struct ell_v *args = body->next;
 	if (body->type == ELL_STRING) {
 		const char *name = body->string;
-		if (!strcmp (name, "block"))
-			return (!args || ell_check (ell, (args = ell_clone_seq (args))))
-				&& ell_check (ell, (*result = ell_list (args)));
+		if (!strcmp (name, "block")) {
+			struct ell_v *cloned = NULL;
+			return (!args || ell_check (ell, (cloned = ell_clone_seq (args))))
+				&& ell_check (ell, (*result = ell_list (cloned)));
+		}
 		if ((body = ell_get (ell, name)))
 			return ell_eval_resolved (ell, body, args, result);
 		return ell_eval_native (ell, name, args, result);
@@ -885,7 +890,7 @@ ell_eval_value (struct ell *ell, struct ell_v *body, struct ell_v **result) {
 
 static bool
 ell_eval_statement
-	(struct ell *ell, struct ell_v *statement, struct ell_v **result) {
+	(struct ell *ell, const struct ell_v *statement, struct ell_v **result) {
 	if (statement->type == ELL_STRING)
 		return ell_check (ell, (*result = ell_clone (statement)));
 
@@ -931,7 +936,7 @@ args_to_scope (struct ell *ell, struct ell_v *args, struct ell_v **scope) {
 
 /// Execute a block and return whatever the last statement returned, eats args
 static bool
-ell_eval_block (struct ell *ell, struct ell_v *body, struct ell_v *args,
+ell_eval_block (struct ell *ell, const struct ell_v *body, struct ell_v *args,
 	struct ell_v **result) {
 	struct ell_v *scope = NULL;
 	if (!args_to_scope (ell, args, &scope)) {
@@ -961,13 +966,14 @@ ell_eval_block (struct ell *ell, struct ell_v *body, struct ell_v *args,
 	(struct ell *ell, struct ell_v *args, struct ell_v **result)
 
 static bool
-ell_eval_any (struct ell *ell, struct ell_v *body, struct ell_v *arg,
-	struct ell_v **result) {
+ell_eval_any (struct ell *ell,
+	const struct ell_v *body, const struct ell_v *arg, struct ell_v **result) {
 	if (body->type == ELL_STRING)
 		return ell_check (ell, (*result = ell_clone (body)));
-	if (arg && !ell_check (ell, (arg = ell_clone (arg))))
+	struct ell_v *cloned_arg = NULL;
+	if (arg && !ell_check (ell, (cloned_arg = ell_clone (arg))))
 		return false;
-	return ell_eval_block (ell, body->head, arg, result);
+	return ell_eval_block (ell, body->head, cloned_arg, result);
 }
 
 static struct ell_v *

ell/stdlib.go

@@ -0,0 +1,513 @@
+//
+// 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.
+//
+
+package ell
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+)
+
+// --- Standard library --------------------------------------------------------
+
+// EvalAny evaluates any value and appends to the result.
+func EvalAny(ell *Ell, body *V, arg *V) (result []V, ok bool) {
+	if body.Type == VTypeString {
+		return []V{*body}, true
+	}
+	var args []V
+	if arg != nil {
+		args = append(args, *arg.Clone())
+	}
+	if res, ok := ell.EvalBlock(body.List, args); ok {
+		return res, true
+	}
+	return nil, false
+}
+
+// NewNumber creates a new string value containing a number.
+func NewNumber(n float64) *V {
+	s := fmt.Sprintf("%f", n)
+	i := len(s)
+	for i > 0 && s[i-1] == '0' {
+		i--
+	}
+	if s[i-1] == '.' {
+		i--
+	}
+	return NewString(s[:i])
+}
+
+// Truthy decides whether any value is logically true.
+func Truthy(v *V) bool {
+	return v != nil && (len(v.List) > 0 || len(v.String) > 0)
+}
+
+// NewBoolean creates a new string value copying the boolean's truthiness.
+func NewBoolean(b bool) *V {
+	if b {
+		return NewString("1")
+	}
+	return NewString("")
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+func fnLocal(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) == 0 || args[0].Type != VTypeList {
+		return ell.Errorf("first argument must be a list")
+	}
+
+	// Duplicates or non-strings don't really matter to us, user's problem.
+	scope := ell.scopes[len(ell.scopes)-1]
+
+	values := args[1:]
+	for _, name := range args[0].List {
+		if len(values) > 0 {
+			scope[name.String] = *values[0].Clone()
+			values = values[1:]
+		}
+	}
+	return nil, true
+}
+
+func fnSet(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) == 0 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+
+	if len(args) > 1 {
+		result = []V{*args[1].Clone()}
+		ell.Set(args[0].String, &result[0])
+		return result, true
+	}
+
+	// We return an empty list for a nil value.
+	if v := ell.Get(args[0].String); v != nil {
+		result = []V{*v.Clone()}
+	} else {
+		result = []V{*NewList(nil)}
+	}
+	return result, true
+}
+
+func fnList(ell *Ell, args []V) (result []V, ok bool) {
+	return []V{*NewList(args)}, true
+}
+
+func fnValues(ell *Ell, args []V) (result []V, ok bool) {
+	return args, true
+}
+
+func fnIf(ell *Ell, args []V) (result []V, ok bool) {
+	var cond, body, keyword int
+	for cond = 0; ; cond = keyword + 1 {
+		if cond >= len(args) {
+			return ell.Errorf("missing condition")
+		}
+		if body = cond + 1; body >= len(args) {
+			return ell.Errorf("missing body")
+		}
+
+		var res []V
+		if res, ok = EvalAny(ell, &args[cond], nil); !ok {
+			return nil, false
+		}
+		if len(res) > 0 && Truthy(&res[0]) {
+			return EvalAny(ell, &args[body], nil)
+		}
+
+		if keyword = body + 1; keyword >= len(args) {
+			break
+		}
+		if args[keyword].Type != VTypeString {
+			return ell.Errorf("expected keyword, got list")
+		}
+
+		switch kw := args[keyword].String; kw {
+		case "else":
+			if body = keyword + 1; body >= len(args) {
+				return ell.Errorf("missing body")
+			}
+			return EvalAny(ell, &args[body], nil)
+		case "elif":
+		default:
+			return ell.Errorf("invalid keyword: %s", kw)
+		}
+	}
+	return nil, true
+}
+
+func fnMap(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 {
+		return ell.Errorf("first argument must be a function")
+	}
+	if len(args) < 2 || args[0].Type != VTypeList {
+		return ell.Errorf("second argument must be a list")
+	}
+
+	body, values := &args[0], &args[1]
+	for _, v := range values.List {
+		res, ok := EvalAny(ell, body, &v)
+		if !ok {
+			return nil, false
+		}
+		result = append(result, res...)
+	}
+	return []V{*NewList(result)}, true
+}
+
+func fnPrint(ell *Ell, args []V) (result []V, ok bool) {
+	for _, arg := range args {
+		if arg.Type != VTypeString {
+			PrintV(os.Stdout, &arg)
+		} else if _, err := os.Stdout.WriteString(arg.String); err != nil {
+			return ell.Errorf("write failed: %s", err)
+		}
+	}
+	return nil, true
+}
+
+func fnCat(ell *Ell, args []V) (result []V, ok bool) {
+	buf := bytes.NewBuffer(nil)
+	for _, arg := range args {
+		if arg.Type != VTypeString {
+			PrintV(buf, &arg)
+		} else {
+			buf.WriteString(arg.String)
+		}
+	}
+	return []V{*NewString(buf.String())}, true
+}
+
+func fnSystem(ell *Ell, args []V) (result []V, ok bool) {
+	var argv []string
+	for _, arg := range args {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		argv = append(argv, arg.String)
+	}
+	if len(argv) == 0 {
+		return ell.Errorf("command name required")
+	}
+
+	cmd := exec.Command(argv[0], argv[1:]...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	// Approximation of system(3) return value to match C ell at least a bit.
+	if err := cmd.Run(); err == nil {
+		return []V{*NewNumber(0)}, true
+	} else if _, ok := err.(*exec.Error); ok {
+		return ell.Errorf("%s", err)
+	} else {
+		return []V{*NewNumber(1)}, true
+	}
+}
+
+func fnParse(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+
+	res, err := NewParser([]byte(args[0].String)).Run()
+	if err != nil {
+		return ell.Errorf("%s", err)
+	}
+	return []V{*NewList(res)}, true
+}
+
+func fnTry(ell *Ell, args []V) (result []V, ok bool) {
+	var body, handler *V
+	if len(args) < 1 {
+		return ell.Errorf("first argument must be a function")
+	}
+	if len(args) < 2 {
+		return ell.Errorf("second argument must be a function")
+	}
+	body, handler = &args[0], &args[1]
+	if result, ok = EvalAny(ell, body, nil); ok {
+		return
+	}
+
+	msg := NewString(ell.Error)
+	ell.Error = ""
+	return EvalAny(ell, handler, msg)
+}
+
+func fnThrow(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+	return ell.Errorf("%s", args[0].String)
+}
+
+func fnPlus(ell *Ell, args []V) (result []V, ok bool) {
+	res := 0.
+	for _, arg := range args {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		var value float64
+		if n, _ := fmt.Sscan(arg.String, &value); n < 1 {
+			return ell.Errorf("invalid number: %s", arg.String)
+		}
+		res += value
+	}
+	return []V{*NewNumber(res)}, true
+}
+
+func fnMinus(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+
+	var res float64
+	if n, _ := fmt.Sscan(args[0].String, &res); n < 1 {
+		return ell.Errorf("invalid number: %f", args[0].String)
+	}
+	if len(args) == 1 {
+		res = -res
+	}
+
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		var value float64
+		if n, _ := fmt.Sscan(arg.String, &value); n < 1 {
+			return ell.Errorf("invalid number: %f", arg.String)
+		}
+		res -= value
+	}
+	return []V{*NewNumber(res)}, true
+}
+
+func fnMultiply(ell *Ell, args []V) (result []V, ok bool) {
+	res := 1.
+	for _, arg := range args {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		var value float64
+		if n, _ := fmt.Sscan(arg.String, &value); n < 1 {
+			return ell.Errorf("invalid number: %s", arg.String)
+		}
+		res *= value
+	}
+	return []V{*NewNumber(res)}, true
+}
+
+func fnDivide(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+
+	var res float64
+	if n, _ := fmt.Sscan(args[0].String, &res); n < 1 {
+		return ell.Errorf("invalid number: %f", args[0].String)
+	}
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		var value float64
+		if n, _ := fmt.Sscan(arg.String, &value); n < 1 {
+			return ell.Errorf("invalid number: %f", arg.String)
+		}
+		res /= value
+	}
+	return []V{*NewNumber(res)}, true
+}
+
+func fnNot(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 {
+		return ell.Errorf("missing argument")
+	}
+	return []V{*NewBoolean(!Truthy(&args[0]))}, true
+}
+
+func fnAnd(ell *Ell, args []V) (result []V, ok bool) {
+	if args == nil {
+		return []V{*NewBoolean(true)}, true
+	}
+	for _, arg := range args {
+		result, ok = EvalAny(ell, &arg, nil)
+		if !ok {
+			return nil, false
+		}
+		if len(result) < 1 || !Truthy(&result[0]) {
+			return []V{*NewBoolean(false)}, true
+		}
+	}
+	return result, true
+}
+
+func fnOr(ell *Ell, args []V) (result []V, ok bool) {
+	for _, arg := range args {
+		result, ok = EvalAny(ell, &arg, nil)
+		if !ok {
+			return nil, false
+		}
+		if len(result) > 0 && Truthy(&result[0]) {
+			return result, true
+		}
+	}
+	return []V{*NewBoolean(false)}, true
+}
+
+func fnEq(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+	etalon, res := args[0].String, true
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		if res = etalon == arg.String; !res {
+			break
+		}
+	}
+	return []V{*NewBoolean(res)}, true
+}
+
+func fnLt(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+	etalon, res := args[0].String, true
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		if res = etalon < arg.String; !res {
+			break
+		}
+		etalon = arg.String
+	}
+	return []V{*NewBoolean(res)}, true
+}
+
+func fnEquals(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+	var first, second float64
+	if n, _ := fmt.Sscan(args[0].String, &first); n < 1 {
+		return ell.Errorf("invalid number: %f", args[0].String)
+	}
+	res := true
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		if n, _ := fmt.Sscan(arg.String, &second); n < 1 {
+			return ell.Errorf("invalid number: %f", arg.String)
+		}
+		if res = first == second; !res {
+			break
+		}
+		first = second
+	}
+	return []V{*NewBoolean(res)}, true
+}
+
+func fnLess(ell *Ell, args []V) (result []V, ok bool) {
+	if len(args) < 1 || args[0].Type != VTypeString {
+		return ell.Errorf("first argument must be string")
+	}
+	var first, second float64
+	if n, _ := fmt.Sscan(args[0].String, &first); n < 1 {
+		return ell.Errorf("invalid number: %f", args[0].String)
+	}
+	res := true
+	for _, arg := range args[1:] {
+		if arg.Type != VTypeString {
+			return ell.Errorf("arguments must be strings")
+		}
+		if n, _ := fmt.Sscan(arg.String, &second); n < 1 {
+			return ell.Errorf("invalid number: %f", arg.String)
+		}
+		if res = first < second; !res {
+			break
+		}
+		first = second
+	}
+	return []V{*NewBoolean(res)}, true
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
+var stdNative = map[string]Handler{
+	"local":  fnLocal,
+	"set":    fnSet,
+	"list":   fnList,
+	"values": fnValues,
+	"if":     fnIf,
+	"map":    fnMap,
+	"print":  fnPrint,
+	"..":     fnCat,
+	"system": fnSystem,
+	"parse":  fnParse,
+	"try":    fnTry,
+	"throw":  fnThrow,
+	"+":      fnPlus,
+	"-":      fnMinus,
+	"*":      fnMultiply,
+	"/":      fnDivide,
+	"not":    fnNot,
+	"and":    fnAnd,
+	"or":     fnOr,
+	"eq?":    fnEq,
+	"lt?":    fnLt,
+	"=":      fnEquals,
+	"<":      fnLess,
+}
+
+var stdComposed = `
+set unless { if (not (@1)) @2 }
+set filter { local [_body _list] @1 @2;
+ map { if (@_body @1) { @1 } } @_list }
+set for { local [_list _body] @1 @2;
+ try { map { @_body @1 } @_list } { if (ne? @1 _break) { throw @1 } } }
+
+set break { throw _break }
+
+# TODO: we should be able to apply them to all arguments
+set ne? { not (eq? @1 @2) }; set le? { ge? @2 @1 }
+set ge? { not (lt? @1 @2) }; set gt? { lt? @2 @1 }
+set <>  { not (= @1 @2)   }; set <=  { >= @2 @1  }
+set >=  { not (< @1 @2)   }; set >   { <  @2 @1  }`
+
+// StdInitialize initializes the ell standard library.
+func StdInitialize(ell *Ell) bool {
+	for name, handler := range stdNative {
+		ell.Native[name] = handler
+	}
+
+	p := NewParser([]byte(stdComposed))
+	program, err := p.Run()
+	if err != nil {
+		return false
+	}
+
+	_, ok := ell.EvalBlock(program, nil)
+	return ok
+}