doc/guide/src/SXML.adoc

   1 SXML
   2 ====
   3
   4 <:SXML:> is an <:IntermediateLanguage:>, translated from <:XML:> by
   5 <:Monomorphise:>, optimized by <:SXMLSimplify:>, and translated by
   6 <:ClosureConvert:> to <:SSA:>.
   7
   8 == Description ==
   9
  10 SXML is a simply-typed version of <:XML:>.
  11
  12 == Implementation ==
  13
  14 * <!ViewGitFile(mlton,master,mlton/xml/sxml.sig)>
  15 * <!ViewGitFile(mlton,master,mlton/xml/sxml.fun)>
  16 * <!ViewGitFile(mlton,master,mlton/xml/sxml-tree.sig)>
  17
  18 == Type Checking ==
  19
  20 <:SXML:> shares the type checker for <:XML:>.
  21
  22 == Details and Notes ==
  23
  24 There are only two differences between <:XML:> and <:SXML:>.  First,
  25 <:SXML:> `val`, `fun`, and `datatype` declarations always have an
  26 empty list of type variables.  Second, <:SXML:> variable references
  27 always have an empty list of type arguments.  Constructors uses can
  28 only have a nonempty list of type arguments if the constructor is a
  29 primitive.
  30
  31 Although we could rely on the type system to enforce these constraints
  32 by parameterizing the <:XML:> signature, <:StephenWeeks:> did so in a
  33 previous version of the compiler, and the software engineering gains
  34 were not worth the effort.