Basic Type System

[maxitg]

Changes

• Implements translations and raw properties of the Yellowstone type system system.
• Composite properties (properties depending on other properties) are not yet implemented.

Comments

• This will mostly be used for Multihistory, however, the Multihistory itself is not yet implemented.
• There are currently no types, so SetReplaceTypeConvert, while implemented, cannot be used for anything.

Examples

• Examples below do not work directly because they use fake types. In order to try them out, do something like

  AppendTo[$ContextPath, "SetReplace`PackageScope`"];

  and then evaluate the definitions (line 15 to 68) from typeSystem.wlt.

• If you do that and then evaluate

  AppendTo[$ContextPath, "SetReplace`A1$typeSystem`PackagePrivate`"];
  Graph[$typeGraph,
       VertexLabels -> {type[name_] :> name, property[name_] :> ToString[name] <> "[...]"},
       VertexStyle -> {type[_] -> Black, property[_] -> White},
       EdgeStyle -> {DirectedEdge[type[_], type[_]] -> Black,
                     DirectedEdge[type[_], property[_]] -> Lighter[Blue, 0.3],
                     DirectedEdge[property[_], property[_]] -> Gray}]

  you will get a type graph from the test file:

  

• You will also be able to do things like these. Here, "EvenInteger" type is converted to "HalfInteger":

  In[] := SetReplaceTypeConvert["HalfInteger"] @ evenInteger[4]
  Out[] = halfInteger[2]

• Here, multipliedHalf property is used on a "HalfInteger" directly:

  In[] := multipliedHalf[5] @ halfInteger[3]
  Out[] = 15

• Here, "HalfInteger" is automatically converted to an "EvenInteger", and then description property is called.

  In[] := description @ halfInteger[3]
  Out[] = "I am an integer 6."

• And here, "EvenInteger" is converted to "HalfInteger" first:

  In[] := multipliedHalf[evenInteger[4], 4]
  Out[] = 8

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This change is 

[maxitg]

I think there is a problem though. If the type system is generic, what do we do with TypeConvert? Surely, it is almost guaranteed to cause namespace collisions. And using packages without adding them to $ContextPath is horribly broken in WL at the moment.

[maxitg]

I renamed TypeConvert -> SetReplaceTypeConvert. This has no possibility of collisions, and I think is more user-friendly than SetReplace`PackageScope`TypeConvert.