diff --git a/proc/src/lib.rs b/proc/src/lib.rs
index 38c8b15..82cb6c8 100644
--- a/proc/src/lib.rs
+++ b/proc/src/lib.rs
@@ -1,3 +1,5 @@
+#![feature(str_as_str)]
+
 extern crate proc_macro;
 
 pub(crate) use std::collections::{BTreeMap, BTreeSet};
@@ -27,7 +29,7 @@ mod proc_command;
 #[proc_macro_attribute]
 pub fn view (meta: TokenStream, item: TokenStream) -> TokenStream {
     use self::proc_view::{ViewDef, ViewMeta, ViewImpl};
-    write_macro(ViewDef(
+    write(ViewDef(
         parse_macro_input!(meta as ViewMeta),
         parse_macro_input!(item as ViewImpl),
     ))
@@ -36,7 +38,7 @@ pub fn view (meta: TokenStream, item: TokenStream) -> TokenStream {
 #[proc_macro_attribute]
 pub fn expose (meta: TokenStream, item: TokenStream) -> TokenStream {
     use self::proc_expose::{ExposeDef, ExposeMeta, ExposeImpl};
-    write_macro(ExposeDef(
+    write(ExposeDef(
         parse_macro_input!(meta as ExposeMeta),
         parse_macro_input!(item as ExposeImpl),
     ))
@@ -45,14 +47,28 @@ pub fn expose (meta: TokenStream, item: TokenStream) -> TokenStream {
 #[proc_macro_attribute]
 pub fn command (meta: TokenStream, item: TokenStream) -> TokenStream {
     use self::proc_command::{CommandDef, CommandMeta, CommandImpl};
-    write_macro(CommandDef(
+    write(CommandDef(
         parse_macro_input!(meta as CommandMeta),
         parse_macro_input!(item as CommandImpl),
     ))
 }
 
-fn write_macro <T: ToTokens> (t: T) -> TokenStream {
+pub(crate) fn write <T: ToTokens> (t: T) -> TokenStream {
     let mut out = TokenStream2::new();
     t.to_tokens(&mut out);
     out.into()
 }
+
+pub(crate) fn write_quote (quote: TokenStream2) -> TokenStream2 {
+    let mut out = TokenStream2::new();
+    for token in quote {
+        out.append(token);
+    }
+    out
+}
+
+pub(crate) fn write_quote_to (out: &mut TokenStream2, quote: TokenStream2) {
+    for token in quote {
+        out.append(token);
+    }
+}
diff --git a/proc/src/proc_command.rs b/proc/src/proc_command.rs
index 8b16dec..8ad7776 100644
--- a/proc/src/proc_command.rs
+++ b/proc/src/proc_command.rs
@@ -4,73 +4,79 @@ use crate::*;
 pub(crate) struct CommandDef(pub(crate) CommandMeta, pub(crate) CommandImpl);
 
 #[derive(Debug, Clone)]
-pub(crate) struct CommandMeta {
-    target: Ident,
-}
+pub(crate) struct CommandMeta(Ident);
 
 #[derive(Debug, Clone)]
 pub(crate) struct CommandImpl(ItemImpl, BTreeMap<Arc<str>, CommandArm>);
 
 #[derive(Debug, Clone)]
-struct CommandVariant(Ident, Vec<FnArg>);
+struct CommandArm(Ident, Vec<FnArg>, ReturnType);
 
 #[derive(Debug, Clone)]
-struct CommandArm(Arc<str>, Ident, Vec<FnArg>, ReturnType);
+struct CommandVariant(Ident, Vec<FnArg>);
 
 impl Parse for CommandMeta {
     fn parse (input: ParseStream) -> Result<Self> {
-        Ok(Self {
-            target: input.parse::<Ident>()?,
-        })
+        Ok(Self(input.parse::<Ident>()?))
     }
 }
 
 impl Parse for CommandImpl {
     fn parse (input: ParseStream) -> Result<Self> {
-        let block = input.parse::<ItemImpl>()?;
+        let block   = input.parse::<ItemImpl>()?;
+        let exposed = Self::collect(&block.items).map_err(|e|input.error(e))?;
+        Ok(Self(block, exposed))
+    }
+}
+
+impl CommandImpl {
+    fn collect (items: &Vec<ImplItem>)
+        -> std::result::Result<BTreeMap<Arc<str>, CommandArm>, String>
+    {
         let mut exposed: BTreeMap<Arc<str>, CommandArm> = Default::default();
-        for item in block.items.iter() {
-            if let ImplItem::Fn(ImplItemFn {
-                sig: Signature { ident, inputs, output, .. }, ..
-            }) = item {
-                let key: Arc<str> =
-                    format!("{}", AsKebabCase(format!("{}", &ident))).into();
-                let variant: Arc<str> =
-                    format!("{}", AsUpperCamelCase(format!("{}", &ident))).into();
+        for item in items.iter() {
+            if let ImplItem::Fn(
+                ImplItemFn { sig: Signature { ident, inputs, output, .. }, .. }
+            ) = item {
+                let key = CommandArm::ident_to_key(&ident);
                 if exposed.contains_key(&key) {
-                    return Err(input.error(format!("already defined: {ident}")));
+                    return Err(format!("already defined: {ident}"));
                 }
                 exposed.insert(key, CommandArm(
-                    variant,
                     ident.clone(),
                     inputs.iter().map(|x|x.clone()).collect(),
                     output.clone(),
                 ));
             }
         }
-        Ok(Self(block, exposed))
+        Ok(exposed)
     }
 }
 
 impl ToTokens for CommandDef {
     fn to_tokens (&self, out: &mut TokenStream2) {
-        let Self(CommandMeta { target }, CommandImpl(block, exposed)) = self;
-        let enumeration = &block.self_ty;
-        let definitions = exposed.values().map(|x|CommandVariant(
-            x.1.clone(),
-            x.2.clone(),
-        ));
-        let implementations = exposed.values().map(|x|CommandArm(
-            x.0.clone(),
-            x.1.clone(),
-            x.2.clone(),
-            x.3.clone(),
-        ));
-        for token in quote! {
-            #block
-            enum #enumeration {
-                #(#definitions)*
+        let Self(CommandMeta(target), CommandImpl(block, exposed)) = self;
+        let enumeration     = &block.self_ty;
+        let variants        = exposed.values().map(|x|CommandArm::to_enum_variant(x, true, true, false));
+        let matchers        = exposed.values().map(CommandArm::to_matcher);
+        let implementations = exposed.values().map(CommandArm::to_implementation);
+        write_quote_to(out, quote! {
+            /// Generated by [tengri_proc].
+            pub enum #enumeration {
+                #(#variants)*
             }
+            #block
+            /// Generated by [tengri_proc].
+            impl<'a> TryFromDsl<'a, #target> for #enumeration {
+                fn try_from_expr (state: &#target, iter: TokenIter) -> Option<Self> {
+                    let mut iter = iter.clone();
+                    match iter.next() {
+                        #(#matchers)*
+                        _ => None
+                    }
+                }
+            }
+            /// Generated by [tengri_proc].
             impl Command<#target> for #enumeration {
                 fn execute (self, state: &mut #target) -> Perhaps<Self> {
                     match self {
@@ -78,12 +84,107 @@ impl ToTokens for CommandDef {
                     }
                 }
             }
-        } {
-            out.append(token)
+        });
+        if exposed.len() > 0 {
+            //panic!("\n{}", quote! {#out});
         }
     }
 }
 
+impl CommandArm {
+    fn to_key (&self) -> Arc<str> {
+        Self::ident_to_key(&self.0)
+    }
+    fn to_enum_variant_ident (&self) -> Ident {
+        Ident::new(&Self::ident_to_enum_variant(&self.0), Span::call_site())
+    }
+    fn ident_to_key (ident: &Ident) -> Arc<str> {
+        format!("{}", AsKebabCase(format!("{ident}"))).into()
+    }
+    fn ident_to_enum_variant (ident: &Ident) -> Arc<str> {
+        format!("{}", AsUpperCamelCase(format!("{ident}"))).into()
+    }
+    fn to_enum_variant (&self, with_types: bool, trailing_comma: bool, with_values: bool) -> TokenStream2 {
+        let mut out = TokenStream2::new();
+        out.append(self.to_enum_variant_ident());
+        let ident = &self.0;
+        if self.1.len() > 2 {
+            out.append(Group::new(Delimiter::Brace, {
+                let mut out = TokenStream2::new();
+                for arg in self.1.iter().skip(2) {
+                    if let FnArg::Typed(PatType { attrs, pat, colon_token, ty }) = arg {
+                        write_quote_to(&mut out, quote! { #pat });
+                        if with_types && with_values {
+                            unreachable!();
+                        }
+                        if with_types {
+                            write_quote_to(&mut out, quote! { : #ty });
+                        }
+                        if with_values {
+                            let take_err = LitStr::new(&format!("{}: missing argument \"{}\" ({})",
+                                quote!{#ident}, quote!{#pat}, quote!{#ty}), Span::call_site());
+                            write_quote_to(&mut out, quote! {
+                                : Context::get(state, &iter.next().expect(#take_err).value)
+                            });
+                        }
+                    } else {
+                        unreachable!("only typed args should be present at this position")
+                    }
+                }
+                out
+            }));
+        }
+        if trailing_comma {
+            out.append(Punct::new(',', Alone));
+        }
+        out
+    }
+    fn to_matcher (&self) -> TokenStream2 {
+        let mut out = TokenStream2::new();
+        let key     = LitStr::new(&self.to_key(), Span::call_site());
+        let ident   = &self.0;
+        let take_args = self.1.iter().skip(2).map(|arg|{
+            if let FnArg::Typed(PatType { attrs, pat, colon_token, ty }) = arg {
+                let take_err = LitStr::new(&format!("{}: missing argument \"{}\" ({})",
+                    quote!{#ident}, quote!{#pat}, quote!{#ty}), Span::call_site());
+                write_quote(quote! {
+                    let #pat: #ty = Context::<#ty>::get(
+                        state,
+                        &iter.next().expect(#take_err).value
+                    );
+                })
+            } else {
+                unreachable!("only typed args should be present at this position")
+            }
+        }).collect::<Vec<_>>();
+        let variant = Self::ident_to_enum_variant(&self.0);
+        let variant = self.to_enum_variant(false, false, true);
+        write_quote(quote! {
+            Some(::tengri::dsl::Token { value: ::tengri::dsl::Value::Key(#key), .. }) => {
+                let mut iter = iter.clone();
+                //#(#take_args)*
+                //let rest = iter; // TODO
+                Some(Self::#variant)
+            },
+        })
+    }
+    fn to_implementation (&self) -> TokenStream2 {
+        let ident = &self.0;
+        let variant = self.to_enum_variant(false, false, false);
+        let mut give_rest = write_quote(quote! {  });
+        let give_args = self.1.iter().skip(2).map(|arg|{
+            if let FnArg::Typed(PatType { attrs, pat, colon_token, ty }) = arg {
+                //let give_err = LitStr::new(&format!("{}: missing value \"{}\" ({})",
+                    //quote!{#ident}, quote!{#pat}, quote!{#ty}), Span::call_site());
+                write_quote(quote! { #pat, })
+            } else {
+                unreachable!("only typed args should be present at this position")
+            }
+        }).collect::<Vec<_>>();
+        write_quote(quote! { Self::#variant => self.#ident(state, #(#give_args)* #give_rest), })
+    }
+}
+
 impl ToTokens for CommandVariant {
     fn to_tokens (&self, out: &mut TokenStream2) {
         let Self(ident, args) = self;
@@ -92,9 +193,7 @@ impl ToTokens for CommandVariant {
         out.append(Group::new(Delimiter::Parenthesis, {
             let mut out = TokenStream2::new();
             for arg in args.iter() {
-                if let FnArg::Typed(PatType {
-                    attrs, pat, colon_token, ty
-                }) = arg {
+                if let FnArg::Typed(PatType { attrs, pat, colon_token, ty }) = arg {
                     out.append(LitStr::new(
                         &format!("{}", quote! { #ty }),
                         Span::call_site()
@@ -110,34 +209,30 @@ impl ToTokens for CommandVariant {
 
 impl ToTokens for CommandArm {
     fn to_tokens (&self, out: &mut TokenStream2) {
-        let Self(symbol, ident, args, returnType) = self;
-        out.append(Punct::new(':', Joint));
-        out.append(Punct::new(':', Alone));
-        out.append(Ident::new("tengri", Span::call_site()));
-        out.append(Punct::new(':', Joint));
-        out.append(Punct::new(':', Alone));
-        out.append(Ident::new("dsl", Span::call_site()));
-        out.append(Punct::new(':', Joint));
-        out.append(Punct::new(':', Alone));
-        out.append(Ident::new("Value", Span::call_site()));
-        out.append(Punct::new(':', Joint));
-        out.append(Punct::new(':', Alone));
-        out.append(Ident::new("Sym", Span::call_site()));
+        let Self(ident, args, returnType) = self;
+        for ident in ["tengri", "dsl", "Value", "Sym"].iter() {
+            out.append(Punct::new(':', Joint));
+            out.append(Punct::new(':', Alone));
+            out.append(Ident::new(ident, Span::call_site()));
+        }
         out.append(Group::new(Delimiter::Parenthesis, {
             let mut out = TokenStream2::new();
+            out.append(self.to_enum_variant_ident());
             for arg in args.iter() {
-                out.append(LitStr::new(&symbol, Span::call_site()).token());
             }
             out
         }));
         out.append(Punct::new('=', Joint));
         out.append(Punct::new('>', Alone));
-        out.append(LitStr::new(&format!("{}", ident), Span::call_site()).token());
+        out.append(Ident::new("self", Span::call_site()));
+        out.append(Punct::new('.', Alone));
+        out.append(ident.clone());
         out.append(Group::new(Delimiter::Parenthesis, {
             let mut out = TokenStream2::new();
             for arg in args.iter() {
                 // TODO
-                //out.append(LitStr::new(&symbol, Span::call_site()).token());
+                out.append(LitStr::new(&self.to_key(), Span::call_site()).token());
+                out.append(Punct::new(',', Alone));
             }
             out
         }));