prowocessing: add documentation of trait experiment

crates/prowocessing/src/experimental/trait_based/element.rs

@@ -1,17 +1,23 @@
+//! The trait and type representations
+
 use crate::experimental::trait_based::data::io::Inputs;
 
 use super::data::io::Outputs;
 
 pub(crate) trait PipelineElement {
+    /// return a static runner function pointer to avoid dynamic dispatch during pipeline execution - Types MUST match the signature
     fn runner(&self) -> fn(&Inputs) -> Outputs;
-    fn signature(&self) -> ElementIo;
+    /// return the signature of the element
+    fn signature(&self) -> ElementSignature;
 }
 
-pub(crate) struct ElementIo {
+/// Type signature for an element used for static checking
+pub(crate) struct ElementSignature {
     pub inputs: Vec<DataType>,
     pub outputs: Vec<DataType>,
 }
 
+/// Data type enum
 #[derive(Clone, Copy, PartialEq, Eq, Debug)]
 pub enum DataType {
     String,