Sunday, July 22, 2012

Phrase Building

Tangent compilation is troublesome compared to traditional languages. The first place this shows up is in Phrase Building. Once the source is parsed, pretty much everything is referred to by a phrase. These phrases need to be curried such that they're boiled down into unary functions that return other functions, on downward until you get to the end of the phrase. In this way, Tangent can work with them in a nice consistent form.

It is one of the core pieces of Tangent though, and over all of its iterations, the implementation has gotten far cleaner and robust. This time though, things are broken up enough to make testing at least mildly sane:

public void ComplexExample() {  
  var parsedSource = Parser.Parse(
    @"(param b:int) (T: kind of any) ++foo (c:string) bar baz (x:int) 
:: module {};"
  var analyzer = new TypeAnalysis_Accessor(
    new List<TypeDefinition>() { parsedSource });  
  var anchor = analyzer.FindAnchorIn(parsedSource.Phrase);  
  var result = analyzer.DeterminePhraseOrder(
    new List<int>() { 2,3,4,1,0,5,6,7,8 }

Wednesday, July 4, 2012

Document update

With the module changes discussed in the previous post, the spec has been updated to include the changes. Slight modifications include:

  • (this). is now optional for field declarations.
  • Initializers are now required for fields except for:
    • Non-abstract types.
    • Enums (the first value is used).
    • Delegates that result in void (a no-op anonymous method is used).
  • Enums may now inherit from other enums. The values list of the sub-enum may not contain values that are not part of the base-enum.
  • Syntax for inferring generic types have been added to all phrases that take parameters (which includes classes and modules).