What's new?

Version 4.1

• Verbatim strings

• Multiple variables declaration:

  var a, b, c: Func<int, int>

• Shorthand method for function registration on host side:

  compiler.RegisterFunction<Func<int, int>>("doubler", x => x * 2);

• Fixes for char & regex literals with escape sequences

Version 4.0

• Pattern matching

• Shorthand assignment operators:

  x += 1

• Enhanced operator semantics for collections - concatenation via + operator and repetition via *:

  var data = new [1; 2; 3]
  data + data // [1; 2; 3; 1; 2; 3]
  data * 2    // the same

• Improved error reporting in Lens Console

Version 3.0

• Automatic inference for lambda argument types:

  new [1; 2; 3; 4; 5]
      |> Where x -> x**2 < 10 // x is inferred to be int

  Also, braces are no longer required if lambda is the only argument of a method.

• Full support for variadic functions and constructors

• Instantiation of empty arrays by size, like in C#

• Partial application for any callable types:

  let sum = (x:int y:int) -> x + y
  let add3 = sum _ 3

• The using block to manage IDisposable resources:

  using x = new FileStream "file.txt" do
      x.Write "some data"

• Underscore name for unneeded arguments in lambdas and functions

Fixed bugs:

• Loop variables are now closured correctly
• Calling a method of a base interface type on derived one now works
• Built-in types now work properly in saved assemblies

Version 2.0

• The parser has been completely rewritten:

  • FSharp and FParsec dependencies removed
  • Huge speed-up
  • Improved error reporting
  • The entire compiler is now a single assembly of 270 kb.

• The for loop that works as both for and foreach loops:

  for a in 1..10 do
      print "a"

• The pure modifier enables automatic memoization for a function

• Unitialized variables: var x : int

• Multiline object initializers

  var x = new [
      "hello there"
      fmt "{0}, {1} and {2}" 1 true 2.5
  ]

• Various syntax improvements:

  • Function definitions became more clear with arguments in parens:

    fun add:int (x:int y:int) -> x + y

  • No braces around the single argument of a lambda:

    getPoints ()
        |> Where (p:Point -> p.X < 10)
        |> Select (p:Point -> fmt "{0}:{1}" p.X p.Y)

  • No braces for if, while and catch:

    try
        if a > 10 then
            fail "error"
        else
            while a < 10 do
                println "a = {0}" a
                a = a + 1
    catch e:Exception
        print "fail: {0}" e.Message

Version 1.1

• Constant expressions are evaluated at compile time
• finally keyword for the try block
• Several bugfixes

Version 1.0

Initial LENS compiler version.