refactor!: replace pack! macros with derive-based pipeline types

Remove the `pack!`, `pack_err!`, `pack_structural!`, and
`pack_err_structural!` macros, replacing all pipeline type definitions
with `#[derive(Grouped)]` and `#[derive(Grouped, Wrap)]` attributes.
This changes the generated struct shape from named-field structs with an
`inner` field to tuple structs accessed via `.0`, and removes the
auto-generated `name` and `info` fields from error types.

1 files changed, 4 insertions, 2 deletions

diff --git a/examples/example-pathfinder/src/sub/mod.rs b/examples/example-pathfinder/src/sub/mod.rs
index cf0a97a..b90c618 100644
--- a/examples/example-pathfinder/src/sub/mod.rs
+++ b/examples/example-pathfinder/src/sub/mod.rs
@@ -3,12 +3,14 @@ use mingling::prelude::*;
 use std::io::Write;
 
 dispatcher!("greet", EntryGreet);
-pack!(ResultName = String);
+
+#[derive(Grouped, Wrap)]
+pub struct ResultName(String);
 
 #[chain]
 pub fn handle_greet(args: EntryGreet) -> Next {
     let name: ResultName = args
-        .inner
+        .0
         .first()
         .cloned()
         .unwrap_or_else(|| "World".to_string())