Major refactor: extract datamodel package.

HACKME.md

@@ -57,16 +57,16 @@ effective instructions for how one could build a copy of that node, using
 the same implementation details.
 
 By example, if some node `n` was made as a `basicnode.plainString`,
-then `n.Prototype()` will be `basicnode.Prototype__String{}`,
+then `n.Prototype()` will be `basicnode.Prototype.String`,
 and `n.Prototype().NewBuilder().AssignString("xyz")` can be presumed to work.
 
 Note there are also limits to this: if a node was built in a flexible way,
 the prototype it reports later may only report what it is now, and not return
 that same flexibility again.
 By example, if something was made as an "any" -- i.e.,
-via `basicnode.Prototype__Any{}.NewBuilder()`, and then *happened* to be assigned a string value --
+via `basicnode.Prototype.Any.NewBuilder()`, and then *happened* to be assigned a string value --
 the resulting node will still carry a `Prototype()` property that returns
-`Prototype__String` -- **not** `Prototype__Any`.
+`basicnode.Prototype.String` -- **not** `basicnode.Prototype.Any`.
 
 #### NodePrototype meets generic transformation
 
@@ -102,7 +102,7 @@ and might be wrapped with additional rules (such as map key uniqueness, field
 name expectations, etc).
 
 (Note that it's also not an exclusive statement about what `AssignNode(Node)` will
-accept; e.g. in many situations, while a `Prototype__MyStringType` might be the prototype
+accept; e.g. in many situations, while a `Prototype.MyStringType` might be the prototype
 returned, any string kinded node can be used in `AssignNode(Node)` and will be
 appropriately converted.)
 

README.md

@@ -28,7 +28,7 @@ if you want to write your own extensions, whether for new Node implementations
 or new codecs, or new higher-order order functions!)
 
 - `github.com/ipld/go-ipld-prime` -- imported as just `ipld` -- contains the core interfaces for IPLD.  The most important interfaces are `Node`, `NodeBuilder`, `Path`, and `Link`.
-- `github.com/ipld/go-ipld-prime/node/basic` -- imported as `basicnode` -- provides concrete implementations of `Node` and `NodeBuilder` which work for any kind of data.
+- `github.com/ipld/go-ipld-prime/node/basicnode` -- imported as `basicnode` -- provides concrete implementations of `Node` and `NodeBuilder` which work for any kind of data.
 - `github.com/ipld/go-ipld-prime/traversal` -- contains higher-order functions for traversing graphs of data easily.
 - `github.com/ipld/go-ipld-prime/traversal/selector` -- contains selectors, which are sort of like regexps, but for trees and graphs of IPLD data!
 - `github.com/ipld/go-ipld-prime/codec` -- parent package of all the codec implementations!