Pnuts Highlights

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First Impression - Hello World
public class HelloWorld { public static void main(String args[]) { System.out.println("Hello World"); } } System.out.println("Hello World")

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Second Impression - Higher-Level Functions, Loops and Data Types
import java.util.*; public class HelloWorld { public static void main (String args[]) { List countries = new ArrayList(); countries.add("Canada"); countries.add("Austria"); countries.add("Brazil"); Collections.sort(countries); for (Iterator it = countries.iterator(); it.hasNext()) System.out.println("Hello " + it.next()); } } use("pnuts.lib") // Standard module that makes sort, println and other functions available. countries = ["Canada", "Austria", "Brazil"] sort(countries) for (country : countries) println("Hello " + country)

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Full Access to the Java API

Pnuts provides far more expressive power than Java, yet retains access to all Java classes. Many times the code can be written nearly identically. You can choose when to use the more expressive Pnuts features. This makes Pnuts very easy for Java developers to pick up.
import java.util.*; List countries = new ArrayList(); countries.add("Brazil"); System.out.println("Hello " + countries.get(0)); import java.util.*; countries = new ArrayList(); countries.add("Brazil"); System.out.println("Hello " + countries.get(0)); countries = ["Brazil"] System.out.println("Hello " + countries[0])

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Automatic Bean Property Access import javax.swing.JFrame frame = JFrame("Example") frame.setSize(640, 480) frame.defaultCloseOperation = JFrame.DISPOSE_ON_CLOSE frame.visible = true System.out.println(frame.title)

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Built-In Syntax for Arrays and Lists
Object[] a = new Object[] { new Integer(1), new Integer(2), new Integer(3) }; System.out.println(a[1]); List l = new ArrayList(); l.add(new Integer(4)); l.add(new Integer(5)); l.add(new Integer(6)); System.out.println(l[2]); use("pnuts.lib") a = [1, 2, 3] println(a[1]) l = list([4, 5, 6]) println(l[2])

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Built-In Syntax for Maps
Map map = new HashMap(); map.put("one", new Integer(1)); map.put("two", new Integer(2)); map.put("three", new Integer(3)); System.out.println(map.get("one")); map = {"one" => 1, "two" => 2, "three" => 3} System.out.println(map["one"])

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More Array, List, and Map Examples

Nested Arrays
a = [1, 2, [4, 5], "hello"] Ranges
sub = l[1..20] sub = l[5..] sub = l[..12] Operator Overloading
[1,2,3] + [4,5,6]

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Element Selection for Arrays and Collections
public List getAddressesInCountry (List addresses, String country) { List result = new ArrayList(); for(Iterator i = data.iterator(); i.hasNext();) { Address address = (Address)i.next(); if (country.equals(address.getCountry())) result.add(address); } return result; } List result = collectCountry(addresses, "Canada"); result = addresses[country == "Canada"]

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Generators and Generator Selection
function integers() { i = 0 while (true) yield i++ } for (i : integers()) { if (i > 5) break System.out.println(i) } gen = integers() System.out.println(gen[45]) for (i : gen[10..14]) System.out.println(i)

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Loop and Index Strings
x = "abc" for (i : x) System.out.println(i) System.out.println(x[1]) // b

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Literal Strings
System.out.println("Literal strings use the backtick character and\n" + "can have characters such as \\, \", \', or newlines\n" + "without the need for escaping.") System.out.println(`Literal strings use the backtick character and can have characters such as \, ", ', or newlines without the need for escaping.`)

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Exception Handling

Pnuts gives detailed error messages when an exception occurs. The Pnuts script and line number even appears in the Java stacktrace. Also, error messages are localized. System.out.println("Hello") System.out.cow() // Exception Exception in thread "main" [file:/C:/pnuts/test.pnut line: 2 column: 1]: java.io.PrintStream@a084f8.cow() [file:/C:/pnuts/test.pnut: line: 2 column: 1] pnuts.lang.PnutsException : no such method: cow target: java.io.PrintStream args: [] at pnuts.compiler.DynamicRuntime._callMethod(DynamicRuntime.java:76) at pnuts.lang.JavaBeansConfiguration.callMethod(JavaBeansConfiguration.java:182) at pnuts.lang.Java2Configuration.callMethod(Java2Configuration.java:200) at pnuts.lang.Runtime.callMethod(Runtime.java:195) at _pnuts_.exec(test.pnut:2) // Script file and line number shows in stacktrace. at pnuts.lang.Runtime.run(Runtime.java:137) at pnuts.compiler.Compiler.execute(Compiler.java:227) at pnuts.compiler.Compiler._start(Compiler.java:469) at pnuts.compiler.Compiler.start(Compiler.java:259) at pnuts.compiler.Compiler.startSet(Compiler.java:253) at pnuts.lang.SimpleNode.accept(SimpleNode.java:174) at pnuts.compiler.CompilerPnutsImpl.accept(CompilerPnutsImpl.java:69) at pnuts.lang.PnutsImpl.load(PnutsImpl.java:186) at pnuts.lang.PnutsImpl.loadFile(PnutsImpl.java:138) at pnuts.lang.Pnuts.loadFile(Pnuts.java:360) at test.Test.main(Test.java:15)

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Performance

Pnuts scripts can be compiled to JVM bytecode for ultimate performance. Pnuts can be run in interpreted mode, it can compile on the fly, or scripts can be compiled beforehand.

Pnuts is one of the fastest scripting languages for the JVM. One secret of the efficient implementation is sophisticated method caching. Usually Pnuts does not use the Reflection API to call methods, even when accessing JavaBean properties. Pnuts generates method proxies on the fly and reuses them. The Reflection API is used only when a method proxy can't be used because of a classloader mismatch. It is true that searching appropriate methods from actual arguments is expensive, but the impact is almost completely invisible, thanks to the method cache. In fact, method calls in Pnuts are even faster than that of Ruby.

Click the images below for more information.

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Modules

The core Pnuts language is kept small and simple. More advanced functionality is provided by a powerful extension module system. This makes Pnuts syntax simple and easy to learn while not losing any advanced functionality. Many other languages tend to add more and more to the core of the language and eventually end up monolithic, difficult to read, and harder to learn.

Pnuts has over 70 modules available here, here, and in source control. Here are some examples of the various modules: IO functions, aspect oriented scripting, Hibernate, POSIX functions, HTML parsing, functional programming, VB script emulation, JSR-223, Jakarta BSF, Win32 COM object access, regular expressions, etc.

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pnuts.servlet Module: Pnuts Server Side Scripting

Pnuts can be used in a servlet container (eg, Tomcat) as the server side scripting language for web applications. Pnuts script can be embedded into HTML pages. This allows Pnuts to be used as a replacement for JSP, PHP, ASP, etc. Pnuts includes a debugger that can be used to step through and inspect your web application scripts. The full power of Java with the ease of scripting in Pnuts makes for a powerful web development tool.

The pnuts.servlet module also includes the ability to perform regex based URL rewriting (eg, Apache's mod_rewrite). This can simplify URLs and help with search engine optimization.

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pnuts.xml Module: XML Node Access
use("pnuts.lib") use("pnuts.xml") doc = readDocument(getURL("http://jroller.com/rss/tomatsu")) nodeAccess(true) // Field access returns nodes as a List. println(doc.rss[0].channel[0].item[2].title[0].text) // Third title. // Index access returns first node. println(doc["rss"]["channel"]["item"]["title"].text) // First title. // Field access on a List of nodes returns a List of values for each of the nodes. allItems = doc["rss"]["channel"].item for (title : allItems.title) println(title.text)

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pnuts.xml Module: XML Node Creation
use("pnuts.xml") nodeEdit(true) // Undefined variables are interpreted as tag functions. xml = html(head(title("pnutsblog")), body(p("test")))() // <html><head><title>pnutsblog</title></head><body><p>test</p></body></html> writeDocument(xml)

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pnuts.lib Module: Aggregate Mode

When aggregate mode is on, field access of a Collection applies the operation to each element and returns a Collection of results.
use("pnuts.lib") x = list([date(1), date(2), date(3)]) aggregateMode(true) println(x.time) // [1, 2, 3] When aggregate mode is on, "Collection[boolExpr]" returns a Collection containing elements where the boolean expression is true.
use("pnuts.lib") x = list([date(1), date(2), date(3)]) aggregateMode(true) println(x[time % 2 == 1].time) // [1, 3] The same can also be done without aggregate mode.
use("pnuts.lib") x = list([date(1), date(2), date(3)]) printAll(x[function (y) y.time % 2 == 1].time) // 1, 3 When aggregate mode is on, "Collection.property = value" sets the bean property or public field on all elements and "Collection[boolExpr] = value" does so where the boolean expression is true.
use("pnuts.lib") x = list([date(1), date(2), date(3)]) aggregateMode(true) x[time % 2 == 1].time = 99 println(x.time) // [99, 2, 99] x.time = 0 println(x.time) // [0, 0, 0] When aggregate mode is on, the binary operations +, -, and * are defined for java.util.Set.
use("pnuts.lib") aggregateMode(true) s1 = set([1,2,3]) s2 = set([1,3,5]) println(s1 + s2) // [1,2,3,5] println(s1 - s2) // [2] println(s1 * s2) // [1, 3]

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metaobject Module: Prototype Based Programming
use("metaobject") function stack(size) { p = prototype() p.array = Object[size] p.pos = 0 p.push = function(this, obj) this.array[this.pos++] = obj p.pop = function (this) this.array[--this.pos] p } s = stack(10) s.push("foo") s.peek = function (this) this.array[this.pos - 1] System.out.println(s.peek())

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pnuts.jdbc Module

Many modules, such as pnuts.jdbc, simply provide a higher level API over an existing Java API. In most cases this allows you to write much less code. However, since access to all of Java is still available, you can use the standard Java API if you like.
use("pnuts.jdbc") conn = openJDBC("org.gjt.mm.mysql.Driver", "jdbc:mysql://localhost/mysql", "root", "") conn.execute("CREATE DATABASE pnuts") try { conn.execute("USE pnuts") conn.execute("CREATE TABLE names (name VARCHAR(30), number INTEGER)") conn.insert("names", {"name" => "Nate", "number" => 999}) conn.update("names", {"name" => "Nate"}, {"number" => 25}) for (row : conn.query("SELECT number FROM names WHERE name='Nate'")) print("Selected row number: " + row["number"] + "<br>") for (row : conn.query("SELECT name FROM names WHERE number=?", [25])) print("Selected row name: " + row["name"] + "<br>") } finally { conn.execute("DROP DATABASE pnuts") conn.close() }

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Written for the JVM

Many other langauges have a mismatch between the JVM and their own type system and other semantics. Pnuts was written from the beginning to be a JVM langauge.

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Conclusion

With Pnuts, you get easy to write code with far more expressive power than the default JVM language (Java).

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Resources

The Pnuts Language
Pnuts User's Guide
Pnuts syntax quick reference
Pnuts downloads
Quickstart Guide
Other articles

Author: Nathan Sweet