diff --git a/core/src/core_macros.rs b/core/src/core_macros.rs
new file mode 100644
index 0000000..b819764
--- /dev/null
+++ b/core/src/core_macros.rs
@@ -0,0 +1,74 @@
+use crate::*;
+
+/// Define and reexport submodules.
+#[macro_export] macro_rules! modules(
+    ($($($feat:literal?)? $name:ident),* $(,)?) => { $(
+        $(#[cfg(feature=$feat)])? mod $name;
+        $(#[cfg(feature=$feat)])? pub use self::$name::*;
+    )* };
+    ($($($feat:literal?)? $name:ident $body:block),* $(,)?) => { $(
+        $(#[cfg(feature=$feat)])? mod $name $body
+        $(#[cfg(feature=$feat)])? pub use self::$name::*;
+    )* };
+);
+
+/// Define a trait for various wrapper types. */
+#[macro_export] macro_rules! flex_trait_mut (
+    ($Trait:ident $(<$($A:ident:$T:ident),+>)? {
+        $(fn $fn:ident (&mut $self:ident $(, $arg:ident:$ty:ty)*) -> $ret:ty $body:block)*
+    })=>{
+        pub trait $Trait $(<$($A: $T),+>)? {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret $body)*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for &mut _T_ {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { (*$self).$fn($($arg),*) })*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for Option<_T_> {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret {
+                if let Some(this) = $self { this.$fn($($arg),*) } else { Ok(None) }
+            })*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Mutex<_T_> {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.get_mut().unwrap().$fn($($arg),*) })*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Arc<::std::sync::Mutex<_T_>> {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.lock().unwrap().$fn($($arg),*) })*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::RwLock<_T_> {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.write().unwrap().$fn($($arg),*) })*
+        }
+        impl<$($($A: $T,)+)?  _T_: $Trait $(<$($A),+>)?> $Trait $(<$($A),+>)? for ::std::sync::Arc<::std::sync::RwLock<_T_>> {
+            $(fn $fn (&mut $self $(,$arg:$ty)*) -> $ret { $self.write().unwrap().$fn($($arg),*) })*
+        }
+    };
+);
+
+/// Implement [`Debug`] in bulk.
+#[macro_export] macro_rules! impl_debug(($($S:ty|$self:ident,$w:ident|$body:block)*)=>{
+    $(impl std::fmt::Debug for $S {
+        fn fmt (&$self, $w: &mut std::fmt::Formatter) -> std::fmt::Result $body
+    })* });
+
+/// Implement [`From`] in bulk.
+#[macro_export] macro_rules! from(
+    ($(<$($lt:lifetime),+>)?|$state:ident:$Source:ty|$Target:ty=$cb:expr) => {
+        impl $(<$($lt),+>)? From<$Source> for $Target {
+            fn from ($state:$Source) -> Self { $cb }}};
+    ($($Struct:ty { $(
+        $(<$($l:lifetime),* $($T:ident$(:$U:ident)?),*>)? ($source:ident: $From:ty) $expr:expr
+    );+ $(;)? })*) => { $(
+        $(impl $(<$($l),* $($T$(:$U)?),*>)? From<$From> for $Struct {
+            fn from ($source: $From) -> Self { $expr } })+ )* }; );
+
+/// Implement [Has].
+#[macro_export] macro_rules! has(($T:ty: |$self:ident : $S:ty| $x:expr) => {
+    impl Has<$T> for $S {
+        fn get (&$self) -> &$T { &$x }
+        fn get_mut (&mut $self) -> &mut $T { &mut $x } } };);
+
+/// Implement [MaybeHas].
+#[macro_export] macro_rules! maybe_has(
+    ($T:ty: |$self:ident : $S:ty| $x:block; $y:block $(;)?) => {
+        impl MaybeHas<$T> for $S {
+            fn get (&$self) -> Option<&$T> $x
+            fn get_mut (&mut $self) -> Option<&mut $T> $y } };);
diff --git a/core/src/lib.rs b/core/src/lib.rs
index b06b55e..0c63c05 100644
--- a/core/src/lib.rs
+++ b/core/src/lib.rs
@@ -1,38 +1,13 @@
+mod core_macros;
 pub(crate) use std::error::Error;
 /// Standard result type.
 pub type Usually<T> = Result<T, Box<dyn Error>>;
 /// Standard optional result type.
 pub type Perhaps<T> = Result<Option<T>, Box<dyn Error>>;
-/// Implement [`Debug`] in bulk.
-#[macro_export] macro_rules! impl_debug(($($S:ty|$self:ident,$w:ident|$body:block)*)=>{
-    $(impl std::fmt::Debug for $S {
-        fn fmt (&$self, $w: &mut std::fmt::Formatter) -> std::fmt::Result $body
-    })* });
-/// Implement [`From`] in bulk.
-#[macro_export] macro_rules! from(
-    ($(<$($lt:lifetime),+>)?|$state:ident:$Source:ty|$Target:ty=$cb:expr) => {
-        impl $(<$($lt),+>)? From<$Source> for $Target {
-            fn from ($state:$Source) -> Self { $cb }}};
-    ($($Struct:ty { $(
-        $(<$($l:lifetime),* $($T:ident$(:$U:ident)?),*>)? ($source:ident: $From:ty) $expr:expr
-    );+ $(;)? })*) => { $(
-        $(impl $(<$($l),* $($T$(:$U)?),*>)? From<$From> for $Struct {
-            fn from ($source: $From) -> Self { $expr } })+ )* }; );
 /// Type-dispatched `get` and `get_mut`.
 pub trait Has<T>: Send + Sync { fn get (&self) -> &T; fn get_mut (&mut self) -> &mut T; }
-/// Implement [Has].
-#[macro_export] macro_rules! has(($T:ty: |$self:ident : $S:ty| $x:expr) => {
-    impl Has<$T> for $S {
-        fn get (&$self) -> &$T { &$x }
-        fn get_mut (&mut $self) -> &mut $T { &mut $x } } };);
 /// Type-dispatched `get` and `get_mut` that return an [Option]-wrapped result.
 pub trait MaybeHas<T>: Send + Sync { fn get (&self) -> Option<&T>; fn get_mut (&mut self) -> Option<&mut T>; }
-/// Implement [MaybeHas].
-#[macro_export] macro_rules! maybe_has(
-    ($T:ty: |$self:ident : $S:ty| $x:block; $y:block $(;)?) => {
-        impl MaybeHas<$T> for $S {
-            fn get (&$self) -> Option<&$T> $x
-            fn get_mut (&mut $self) -> Option<&mut $T> $y } };);
 /// May compute a `RetVal` from `Args`.
 pub trait Eval<Args, RetVal> {
     /// A custom operation on [Args] that may return [Result::Err] or [Option::None].
diff --git a/dsl/src/dsl.rs b/dsl/src/dsl.rs
index 530e4f5..8f83589 100644
--- a/dsl/src/dsl.rs
+++ b/dsl/src/dsl.rs
@@ -1,5 +1,6 @@
 //#![feature(adt_const_params)]
 //#![feature(type_alias_impl_trait)]
+#![feature(if_let_guard)]
 #![feature(impl_trait_in_fn_trait_return)]
 #![feature(const_precise_live_drops)]
 extern crate const_panic;
@@ -31,10 +32,6 @@ impl Dsl for std::sync::Arc<str> {
     fn src (&self) -> &str { self.as_ref() }
 }
 
-impl<D: Dsl> Dsl for Option<D> {
-    fn src (&self) -> &str { if let Some(dsl) = self { dsl.src() } else { "" } }
-}
-
 impl<D: Dsl> Dsl for &D {
     fn src (&self) -> &str { (*self).src() }
 }
@@ -43,6 +40,14 @@ impl<D: Dsl> Dsl for &mut D {
     fn src (&self) -> &str { (**self).src() }
 }
 
+impl<D: Dsl> Dsl for std::sync::Arc<D> {
+    fn src (&self) -> &str { (*self).src() }
+}
+
+impl<D: Dsl> Dsl for Option<D> {
+    fn src (&self) -> &str { if let Some(dsl) = self { dsl.src() } else { "" } }
+}
+
 /// DSL-specific result type.
 pub type DslResult<T> = Result<T, DslError>;
 
diff --git a/dsl/src/dsl_types.rs b/dsl/src/dsl_types.rs
index 0a5402d..c9d69a1 100644
--- a/dsl/src/dsl_types.rs
+++ b/dsl/src/dsl_types.rs
@@ -1,9 +1,7 @@
 use crate::*;
-
 macro_rules! iter_chars(($source:expr => |$i:ident, $c:ident|$val:expr)=>{
     while let Some((($i, $c), next)) = char_indices($source).next() {
         $source = next.as_str(); $val } });
-
 macro_rules! def_peek_seek(($peek:ident, $seek:ident, $seek_start:ident, $seek_length:ident)=>{
     /// Find a slice corrensponding to a syntax token.
     const fn $peek (source: &str) -> DslPerhaps<&str> {
@@ -22,27 +20,56 @@ macro_rules! def_peek_seek(($peek:ident, $seek:ident, $seek_start:ident, $seek_l
             Ok(None) => Ok(None),
             Err(e) => Err(e) } } });
 
-const fn is_whitespace (c: char) -> bool { matches!(c, ' '|'\n'|'\r'|'\t') }
+pub const fn peek (mut src: &str) -> DslPerhaps<&str> {
+    Ok(Some(match () {
+        _ if let Ok(Some(exp))  = exp_peek(src) => exp,
+        _ if let Ok(Some(sym))  = sym_peek(src) => sym,
+        _ if let Ok(Some(key))  = key_peek(src) => key,
+        _ if let Ok(Some(num))  = num_peek(src) => num,
+        _ if let Ok(Some(text)) = text_peek(src) => text,
+        _ => {
+            iter_chars!(src => |_i, c| if !is_whitespace(c) {
+                return Err(Unexpected(c))
+            });
+            return Ok(None)
+        }
+    }))
+}
 
-pub trait DslExp: Dsl {
-    fn exp (&self) -> DslPerhaps<impl DslExp> {
-        todo!();
-        Ok(Some(self))
+pub const fn seek (mut src: &str) -> DslPerhaps<(usize, usize)> {
+    Ok(Some(match () {
+        _ if let Ok(Some(exp))  = exp_seek(src) => exp,
+        _ if let Ok(Some(sym))  = sym_seek(src) => sym,
+        _ if let Ok(Some(key))  = key_seek(src) => key,
+        _ if let Ok(Some(num))  = num_seek(src) => num,
+        _ if let Ok(Some(text)) = text_seek(src) => text,
+        _ => {
+            iter_chars!(src => |_i, c| if !is_whitespace(c) {
+                return Err(Unexpected(c))
+            });
+            return Ok(None)
+        }
+    }))
+}
+
+const fn is_whitespace (c: char) -> bool { matches!(c, ' '|'\n'|'\r'|'\t') }
+pub trait DslExp<'s>: Dsl + From<&'s str> {
+    fn exp (&'s self) -> DslPerhaps<Self> {
+        Ok(exp_peek(self.src())?.map(Into::into))
     }
-    fn exp_head (&self) -> DslPerhaps<impl Dsl> {
-        todo!();
-        Ok(Some(self))
+    fn head (&'s self) -> DslPerhaps<Self> {
+        Ok(peek(&self.src()[1..])?.map(Into::into))
     }
-    fn exp_tail (&self) -> DslPerhaps<impl DslExp> {
-        todo!();
-        Ok(Some(self))
-    }
-    fn exp_next (&mut self) -> DslPerhaps<impl Dsl> {
-        todo!();
-        Ok(Some(self))
+    fn tail (&'s self) -> DslPerhaps<Self> {
+        Ok(if let Some((head_start, head_len)) = seek(&self.src()[1..])? {
+            peek(&self.src()[(1+head_start+head_len)..])?.map(Into::into)
+        } else {
+            None
+        })
     }
 }
-impl<D: Dsl> DslExp for D {}
+//impl<'s, D: DslExp<'s>> DslExp<'s> for Option<D> {}
+impl<'s, D: Dsl + From<&'s str>> DslExp<'s> for D {}
 def_peek_seek!(exp_peek, exp_seek, exp_seek_start, exp_seek_length);
 const fn is_exp_start (c: char) -> bool { matches!(c, '(') }
 const fn is_exp_end (c: char) -> bool { matches!(c, ')') }
diff --git a/input/src/input_dsl.rs b/input/src/input_dsl.rs
index 0bec9a8..8e87506 100644
--- a/input/src/input_dsl.rs
+++ b/input/src/input_dsl.rs
@@ -54,20 +54,37 @@ impl<E: Clone + Ord, C> EventMap<E, C> {
     }
     /// Create event map from string.
     pub fn from_source (source: impl AsRef<str>) -> Usually<Self> where E: From<Arc<str>> {
-        Self::from_dsl(source.as_ref())
+        Self::from_dsl(&mut source.as_ref())
     }
     /// Create event map from DSL tokenizer.
-    pub fn from_dsl (mut dsl: impl Dsl) -> Usually<Self> where E: From<Arc<str>> {
+    pub fn from_dsl <'s, D: DslExp<'s> + 's> (dsl: &'s mut D) -> Usually<Self> where E: From<Arc<str>> {
         let mut map: Self = Default::default();
-        while let Some(dsl) = dsl.exp_next()? {
-            if let Some(path) = dsl.text()? {
-                map.0.extend(Self::from_path(PathBuf::from(path.as_ref() as &str))?.0)
-            } else if dsl.exp_head()?.key()? == Some("if") {
-                todo!()
-                //map.add(sym.into(), Binding::from_dsl(dsl.exp_tail())?);
-            } else if let Some(sym) = dsl.exp_head()?.sym()? {
-                todo!()
-                //map.add(sym.into(), Binding::from_dsl(dsl.exp_tail())?);
+        let mut head: Option<D> = dsl.head()?;
+        let mut tail: Option<D> = dsl.tail()?;
+        loop {
+            if let Some(ref token) = head {
+                if let Some(ref text) = token.text()? {
+                    map.0.extend(Self::from_path(PathBuf::from(text))?.0);
+                    continue
+                }
+                //if let Some(ref exp) = token.exp()? {
+                    ////_ if let Some(sym) = token.head()?.sym()?.as_ref() => {
+                        ////todo!()
+                    ////},
+                    ////_ if Some(&"if") == token.head()?.key()?.as_ref() => {
+                        ////todo!()
+                    ////},
+                    //return Err(format!("unexpected: {:?}", token.exp()).into())
+                //}
+                return Err(format!("unexpected: {token:?}").into())
+            } else {
+                break
+            }
+            if let Some(next) = tail {
+                head = next.head()?;
+                tail = next.tail()?;
+            } else {
+                break
             }
         }
         Ok(map)
diff --git a/input/src/input_handle.rs b/input/src/input_handle.rs
index 2be276c..ed13cdc 100644
--- a/input/src/input_handle.rs
+++ b/input/src/input_handle.rs
@@ -35,43 +35,48 @@ pub trait Input: Sized {
     }
 }
 
-/// Handle input
-pub trait Handle<E: Input> {
+flex_trait_mut!(Handle <E: Input> {
     fn handle (&mut self, _input: &E) -> Perhaps<E::Handled> {
         Ok(None)
     }
-}
-impl<E: Input, H: Handle<E>> Handle<E> for &mut H {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        (*self).handle(context)
-    }
-}
-impl<E: Input, H: Handle<E>> Handle<E> for Option<H> {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        if let Some(handle) = self {
-            handle.handle(context)
-        } else {
-            Ok(None)
-        }
-    }
-}
-impl<H, E: Input> Handle<E> for Mutex<H> where H: Handle<E> {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        self.get_mut().unwrap().handle(context)
-    }
-}
-impl<H, E: Input> Handle<E> for Arc<Mutex<H>> where H: Handle<E> {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        self.lock().unwrap().handle(context)
-    }
-}
-impl<H, E: Input> Handle<E> for RwLock<H> where H: Handle<E> {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        self.write().unwrap().handle(context)
-    }
-}
-impl<H, E: Input> Handle<E> for Arc<RwLock<H>> where H: Handle<E> {
-    fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
-        self.write().unwrap().handle(context)
-    }
-}
+});
+
+//pub trait Handle<E: Input> {
+    //fn handle (&mut self, _input: &E) -> Perhaps<E::Handled> {
+        //Ok(None)
+    //}
+//}
+//impl<E: Input, H: Handle<E>> Handle<E> for &mut H {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //(*self).handle(context)
+    //}
+//}
+//impl<E: Input, H: Handle<E>> Handle<E> for Option<H> {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //if let Some(handle) = self {
+            //handle.handle(context)
+        //} else {
+            //Ok(None)
+        //}
+    //}
+//}
+//impl<H, E: Input> Handle<E> for Mutex<H> where H: Handle<E> {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //self.get_mut().unwrap().handle(context)
+    //}
+//}
+//impl<H, E: Input> Handle<E> for Arc<Mutex<H>> where H: Handle<E> {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //self.lock().unwrap().handle(context)
+    //}
+//}
+//impl<H, E: Input> Handle<E> for RwLock<H> where H: Handle<E> {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //self.write().unwrap().handle(context)
+    //}
+//}
+//impl<H, E: Input> Handle<E> for Arc<RwLock<H>> where H: Handle<E> {
+    //fn handle (&mut self, context: &E) -> Perhaps<E::Handled> {
+        //self.write().unwrap().handle(context)
+    //}
+//}
diff --git a/proc/src/proc_view.rs b/proc/src/proc_view.rs
index bd44c96..13a5d5c 100644
--- a/proc/src/proc_view.rs
+++ b/proc/src/proc_view.rs
@@ -56,13 +56,13 @@ impl ViewDef {
         let builtins = builtins_with_boxes_output(quote! { #output })
             .map(|(builtin, builtin_ty)|match builtin {
                 Single(name) => quote! {
-                    if dsl.exp_head()?.key()? == Some(#name) {
+                    if dsl.head()?.key()? == Some(#name) {
                         return Ok(Some(#builtin_ty::from_dsl_or_else(self, dsl,
                             ||format!("failed to load builtin").into())?.boxed()))
                     }
                 },
                 Prefix(name) => quote! {
-                    if let Some(key) = dsl.exp_head()?.key()? && key.starts_with(#name) {
+                    if let Some(key) = dsl.head()?.key()? && key.starts_with(#name) {
                         return Ok(Some(#builtin_ty::from_dsl_or_else(self, dsl,
                             ||format!("failed to load builtin").into())?.boxed()))
                     }