The Slash Programming Language

Slash is a new programming language for the web. It is mainly inspired by Ruby and PHP, with hints of Python and Perl.

PHP is a great tool that is virtually unmatched in its domain - ie. ‘slap a script on a server and have it run’. The problem is that PHP’s idiosyncrasies make it awkward and sometimes even painful to program in.

Slash combines PHP’s simple execution model with the elegance of Ruby’s object model. The result is a language that lets you achieve results quickly while being a joy to use.

Overview

<%
    db = MySQL.new("localhost", "my-user", "s3cr3t");
    db.use("my-database");
%>
<h1>People</h1>
<ul>
    <% for person in db.query("SELECT * FROM people") { %>
        <li><%= person["name"] %></li>
    <% } else { %>
        <li><em>No people found!</em></li>
    <% } %>
</ul>

Features

• Singleton methods

  obj = Object.new;
  def obj.foo {
      1 + 2;
  }
  print(obj.foo); # => 3
  

• Yada-yada operator

  def solve_halting_problem {
      ...;
  }
  solve_halting_problem(); # !! NotImplementedError
  

• Unicode friendly

  print("你好世界".length); # => 4
  
  print("åéîøü".upper); # => ÅÉÎØÜ
  

• Destructuring assignment

  def what {
      "switcheroo old the".split;
  }
  [c, b, a] = what();
  print(a, b, c); # => the old switcheroo
  

• Lambda expressions

  def foo(callable) {
      callable.call(9);
  }
  
  print(foo(\x { x * x }), "\n"); # => 81
  
  print(foo(λ x . x ** x), "\n"); # => 387420489
  

• Method binding syntax

  print([1, 2, 3, 4].map(2:*)); # => [2, 4, 6, 8]
  

• Everything is an expression

  obj = class X {
      print(def to_s {
          if false {
              "nope";
          } else {
              "an instance of X";
          }
      }, "\n"); # => #<Method:0xdeadbeef>
  }.new;
  print(obj); # => an instance of X
  

• Regular expression literals

  md = %r{It's (?<weather>\w+) in (?<city>\w+)}.match("It's raining in Melbourne");
  print(md["city"], ": ", md["weather"]); # => Melbourne: raining
  

• Functional enumerable manipulation

  print((1..100)
        .filter(\x { x % 2 == 0 })
        .map(\x { x * x })
        .reduce(\(a, b) { a + b })); # => 171700
  

• Postfix conditionals

  print("hello") if true;        # => hello
  print("goodbye") unless false; # => goodbye
  

• HTML escaping by default

  Username: <%= user.username %> <!-- => Username: &lt;script&gt;alert(&quot;xss&quot;)&lt;/script&gt; -->
  

• Raw output if you really need it

  <%!! render_markdown(doc.source) %> <!-- => <b>hello world</b> -->
  

• Compound and conditional assignment

  x = 3;
  x *= 2;
  x += 1;
  print(x); # => 7
  
  @cache ||= expensive_operation();
  

• Automatic bignum promotion

  x = 100;
  print(x, " :: ", x.class, "\n"); # => 100 :: Int
  x *= 1000;
  x *= 10000;
  x *= 100000;
  x *= 1000000;
  print(x, " :: ", x.class, "\n"); # => 100000000000000000000 :: Bignum
  

• Operator overloading and magic methods

  class Dots {
      def init(count) {
          @dots = "." * count;
      }
  
      def to_s {
          @dots;
      }
  
      def count {
          @dots.length;
      }
  
      def +(other) {
          Dots.new(self.count + other.count);
      }
  
      def succ {
          self + Dots.new(1);
      }
  
      def <=(other) {
          self.count <= other.count;
      }
  }
  
  three = Dots.new(3);
  five = Dots.new(5);
  print(three + five, "\n"); # => ........
  
  print((three..five).join("; ")); # => ...; ....; .....
  

• Exception stack frames are objects

  def bar {
      throw Error.new;
  }
  
  def foo {
      bar();
  }
  
  try {
      foo();
  } catch e {
      for frame in e.backtrace {
          print(e.method, " ", e.file, ":", e.line, "\n");
      }
  }