a simple solution to hygiene problem

[liufengyun]

This is a simple while practical solution to the hygiene problem: it still allows programmers to do the hack if scala.gestalt.options.unsafe is imported. By default, only fully-qualified name or symbol-based name is supported.

When scala supports literal types, we can do better with the API:

      def Ident(name: "_root_"): Tree
      def Ident(name: "scala")(implcit dummy: C): Tree

[liufengyun]

It's really nice that the implementation of monadless is hygienic, and optional is partly hygienic.

[valdisxp1]

This is great, forcing to use symbols, existing Idents or full paths by default makes sense.
Unsafe can also be imported in small scopes makes for good design.

Other than the two minor comments on implementation, this looks good.

[valdisxp1]

This should be a fold over TypeTree not TermTree.
It is possible to eliminate the recursive calls if we handle the head specially not the last.

parts.tail.foldLeft[TypeTree](TypeSelect(tree,parts.head)){
  (prefix, name) =>
    TypeSelect(prefix, name)
}

[liufengyun]

In a type select such as scala.collection.Set, only the last part is TypeSelect, scala.collection is still Select.

[valdisxp1]

This can be done more easily

parts.foldLeft[TermTree](tree) {
  (prefix, name) =>
       Select(prefix, name)  
 }

[liufengyun]

Indeed, thanks a lot.