wip: start replacing EdnViewData with EdnProvide

input/src/edn_command.rs

@@ -2,21 +2,51 @@ use crate::*;
 use EdnItem::*;
 
 #[macro_export] macro_rules! edn_command {
-    ($Command:ty : |$state:ident:$State:ty| {
-        $(($key:literal [$($arg:ident : $type:ty),*] $command:expr))*
-    }) => {
+    ($Command:ty : |$state:ident:$State:ty| { $((
+        // identifier
+        $key:literal [
+            // named parameters
+            $(
+                // argument name
+                $arg:ident
+                // if type is not provided defaults to EdnItem
+                $(
+                    // type:name separator
+                    :
+                    // argument type
+                    $type:ty
+                )?
+            ),* 
+            // rest of parameters
+            $(, ..$rest:ident)?
+        ]
+        // bound command:
+        $command:expr
+    ))* }) => {
         impl EdnCommand<$State> for $Command {
             fn from_edn <'a> ($state: &$State, head: &EdnItem<&str>, tail: &'a [EdnItem<String>]) -> Self {
-                match (head, tail) {
-                    $((EdnItem::Key($key), [$($arg),*]) => {
-                        $(let $arg: $type = EdnProvide::<$type>::get_or_fail($state, $arg);)*
-                        $command
-                    },)*
-                    _ => panic!("no such command")
-                }
+                $(if let (EdnItem::Key($key), [ // if the identifier matches
+                    // bind argument ids
+                    $($arg),*
+                    // bind rest parameters
+                    $(, $rest @ ..)?
+                ]) = (head, tail) {
+                    $(
+                        $(let $arg: Option<$type> = EdnProvide::<$type>::get($state, $arg);)?
+                    )*
+                    //$(edn_command!(@bind $state => $arg $(?)? : $type);)*
+                    return $command
+                })*
+                panic!("no such command")
             }
         }
-    }
+    };
+    (@bind $state:ident =>$arg:ident ? : $type:ty) => {
+        let $arg: Option<$type> = EdnProvide::<$type>::get($state, $arg);
+    };
+    (@bind $state:ident => $arg:ident : $type:ty) => {
+        let $arg: $type = EdnProvide::<$type>::get_or_fail($state, $arg);
+    };
 }
 
 /// Turns an EDN symbol sequence into a command enum variant.

input/src/edn_provide.rs

@@ -23,3 +23,12 @@ pub trait EdnProvide<U> {
         self.get(edn).expect("no value")
     }
 }
+
+impl<T: EdnProvide<U>, U> EdnProvide<U> for &T {
+    fn get <S: AsRef<str>> (&self, edn: &EdnItem<S>) -> Option<U> {
+        (*self).get(edn)
+    }
+    fn get_or_fail <S: AsRef<str>> (&self, edn: &EdnItem<S>) -> U {
+        (*self).get_or_fail(edn)
+    }
+}