Impulse

A small, dynamically typed, message based prototypical language written with simplicity in mind.

Impulse is a small, dynamically typed, message based prototypical language written with simplicity in mind. Its syntax and semantics are derived mostly from Ruby, Io, Smalltalk and Dylan, and it's purpose is to be a smarter 'scripting' language, with features such as trait composition, extension methods (wich solves monkey-patching), and constructor field initialization. A core goal is to keep the language, both the implementation and the syntax, small and lightweight.

Examples

100 Doors [http://rosettacode.org/wiki/100_doors]

// Unoptimized version

doors = [false] ** 100

(1..100) each: |i| do
   (i..100) each: |j| do
      doors[j] = doors[j] not
   end, step: i
end

// Optimized version

doors = [false] ** 100

(1..100 sqrt) each: |i| do
   doors[i * i] = true
end

Transform a few names into a different format

names = ["mark twain", "john smith"]

result = names map: |name| do
   name split: " " $ map: #capitalize $ reverse $ join: ", "
end

// The $ operator simply groups expressions. This is equivalent:

result = names map: |name| do
   (((name split: " ") map: #capitalize) reverse) join: ", "
end

Generate an 8-bit binary literal (not yet valid in Impulse)

"0b" ++ (0..1 $ sample: 8 $ join: "")

// This creates a string such as:

"0b01100110"

Different ways to compose messages

"abc" upper-case                   // A normal message-send
"abc" with: #upper-case            // Passing a symbol to use as the message
"abc" with: |c| c upper-case       // Passing a block, useful for ad-hoc chaining
"abc" send: #upper-case, args: []  // Meta-message-send with symbol and arguments array

Define a simple bank-account object

object <bank-account>

   field balance = 0
   
   method deposit: amount
      self.balance = self.balance + amount
   end

end

account = <bank-account> [#balance => 100]

Download

The latest implementation is written in Ruby, which facilitates rapid prototyping, provides garbage collection, etc., and can be found here: https://github.com/mikeaustin/impulse-language/tree/master/ruby2

You can run the interactive interpreter, or REPL, by typing:

ruby impulse.rb

To execute code in a file, simply add the filename afterwards. For example,

ruby impulse.rb tests.im

Reference

• The Impulse Programming Language
• Impulse: Why Another New Language?
• Impulse Runtime Documentation
• Impulse Example: Standard Library
• Impulse Runtime Class Reference

Related

• Predicate Dispatching: A Unified Theory of Dispatch
• Dylan Singleton Types [Dylan Reference Manual]
• Haskell/Pattern matching
• The Self Programming Language
• Prototypes with Multiple Dispatch [PDF]

Contact

You can reach me with any questions or comments at mike AT mike-austin DOT com