diff --git a/src/input.rs b/src/input.rs
index 1a35cd0..a304855 100644
--- a/src/input.rs
+++ b/src/input.rs
@@ -160,20 +160,29 @@ impl<'a> Input for &'a str {
     }
 }
 
-pub trait InputMatch<Pat> {
-    fn match_left(&self, pat: &'static Pat) -> Option<usize>;
-    fn match_right(&self, pat: &'static Pat) -> Option<usize>;
+pub trait InputMatch<Pat: ?Sized> {
+    fn match_left(&self, pat: &Pat) -> Option<usize>;
+    fn match_right(&self, pat: &Pat) -> Option<usize>;
 }
 
-impl<T: PartialEq> InputMatch<&'static [T]> for [T] {
-    fn match_left(&self, pat: &&[T]) -> Option<usize> {
+impl<I: ?Sized + InputMatch<Pat>, Pat: ?Sized> InputMatch<&'_ Pat> for I {
+    fn match_left(&self, &pat: &&Pat) -> Option<usize> {
+        self.match_left(pat)
+    }
+    fn match_right(&self, &pat: &&Pat) -> Option<usize> {
+        self.match_right(pat)
+    }
+}
+
+impl<T: PartialEq> InputMatch<[T]> for [T] {
+    fn match_left(&self, pat: &[T]) -> Option<usize> {
         if self.starts_with(pat) {
             Some(pat.len())
         } else {
             None
         }
     }
-    fn match_right(&self, pat: &&[T]) -> Option<usize> {
+    fn match_right(&self, pat: &[T]) -> Option<usize> {
         if self.ends_with(pat) {
             Some(pat.len())
         } else {
@@ -201,15 +210,15 @@ impl<T: PartialOrd> InputMatch<RangeInclusive<T>> for [T] {
     }
 }
 
-impl InputMatch<&'static str> for str {
-    fn match_left(&self, pat: &&str) -> Option<usize> {
+impl InputMatch<str> for str {
+    fn match_left(&self, pat: &str) -> Option<usize> {
         if self.starts_with(pat) {
             Some(pat.len())
         } else {
             None
         }
     }
-    fn match_right(&self, pat: &&str) -> Option<usize> {
+    fn match_right(&self, pat: &str) -> Option<usize> {
         if self.ends_with(pat) {
             Some(pat.len())
         } else {
diff --git a/src/parser.rs b/src/parser.rs
index c76534a..7474e2d 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -6,27 +6,27 @@ use std::collections::HashMap;
 use std::fmt;
 use std::hash::Hash;
 
-pub struct Parser<'a, 'i, G: GrammarReflector, I: Input> {
-    state: &'a mut ParserState<'i, G, I>,
+pub struct Parser<'a, 'i, G: GrammarReflector, I: Input, Pat> {
+    state: &'a mut ParserState<'i, G, I, Pat>,
     result: Range<'i>,
     remaining: Range<'i>,
 }
 
-struct ParserState<'i, G: GrammarReflector, I: Input> {
+struct ParserState<'i, G: GrammarReflector, I: Input, Pat> {
     forest: ParseForest<'i, G, I>,
     last_input_pos: Index<'i, Unknown>,
-    expected_pats: Vec<&'static dyn fmt::Debug>,
+    expected_pats: Vec<Pat>,
 }
 
 #[derive(Debug)]
-pub struct ParseError<A> {
+pub struct ParseError<A, Pat> {
     pub at: A,
-    pub expected: Vec<&'static dyn fmt::Debug>,
+    pub expected: Vec<Pat>,
 }
 
-pub type ParseResult<A, T> = Result<T, ParseError<A>>;
+pub type ParseResult<A, Pat, T> = Result<T, ParseError<A, Pat>>;
 
-impl<'i, P, G, I: Input> Parser<'_, 'i, G, I>
+impl<'i, P, G, I: Input, Pat> Parser<'_, 'i, G, I, Pat>
 where
     // FIXME(eddyb) these shouldn't be needed, as they are bounds on
     // `GrammarReflector::ParseNodeKind`, but that's ignored currently.
@@ -36,8 +36,8 @@ where
     pub fn parse_with(
         grammar: G,
         input: I,
-        f: impl for<'i2> FnOnce(Parser<'_, 'i2, G, I>) -> Option<ParseNode<'i2, P>>,
-    ) -> ParseResult<I::SourceInfoPoint, OwnedParseForestAndNode<G, P, I>> {
+        f: impl for<'i2> FnOnce(Parser<'_, 'i2, G, I, Pat>) -> Option<ParseNode<'i2, P>>,
+    ) -> ParseResult<I::SourceInfoPoint, Pat, OwnedParseForestAndNode<G, P, I>> {
         ErasableL::indexing_scope(input.to_container(), |lifetime, input| {
             let range = Range(input.range());
             let mut state = ParserState {
@@ -99,7 +99,7 @@ where
         &'a mut self,
         result: Range<'i>,
         remaining: Range<'i>,
-    ) -> Parser<'a, 'i, G, I> {
+    ) -> Parser<'a, 'i, G, I, Pat> {
         // HACK(eddyb) enforce that `result` and `remaining` are inside `self`.
         assert_eq!(self.result, Range(self.remaining.frontiers().0));
         let full_new_range = result.join(remaining.0).unwrap();
@@ -113,19 +113,19 @@ where
         }
     }
 
-    pub fn input_consume_left<'a, Pat: fmt::Debug>(
+    pub fn input_consume_left<'a, SpecificPat: Into<Pat>>(
         &'a mut self,
-        pat: &'static Pat,
-    ) -> Option<Parser<'a, 'i, G, I>>
+        pat: SpecificPat,
+    ) -> Option<Parser<'a, 'i, G, I, Pat>>
     where
-        I::Slice: InputMatch<Pat>,
+        I::Slice: InputMatch<SpecificPat>,
     {
         let start = self.remaining.first();
         if start > self.state.last_input_pos {
             self.state.last_input_pos = start;
             self.state.expected_pats.clear();
         }
-        match self.state.forest.input(self.remaining).match_left(pat) {
+        match self.state.forest.input(self.remaining).match_left(&pat) {
             Some(n) => {
                 let (matching, after, _) = self.remaining.split_at(n);
                 if n > 0 {
@@ -140,22 +140,22 @@ where
             }
             None => {
                 if start == self.state.last_input_pos {
-                    self.state.expected_pats.push(pat);
+                    self.state.expected_pats.push(pat.into());
                 }
                 None
             }
         }
     }
 
-    pub fn input_consume_right<'a, Pat>(
+    pub fn input_consume_right<'a, SpecificPat>(
         &'a mut self,
-        pat: &'static Pat,
-    ) -> Option<Parser<'a, 'i, G, I>>
+        pat: SpecificPat,
+    ) -> Option<Parser<'a, 'i, G, I, Pat>>
     where
-        I::Slice: InputMatch<Pat>,
+        I::Slice: InputMatch<SpecificPat>,
     {
         // FIXME(eddyb) implement error reporting support like in `input_consume_left`
-        match self.state.forest.input(self.remaining).match_right(pat) {
+        match self.state.forest.input(self.remaining).match_right(&pat) {
             Some(n) => {
                 let (before, matching, _) = self.remaining.split_at(self.remaining.len() - n);
                 Some(Parser {
diff --git a/src/proc_macro.rs b/src/proc_macro.rs
index 4a6a0f7..ba73e78 100644
--- a/src/proc_macro.rs
+++ b/src/proc_macro.rs
@@ -3,6 +3,8 @@ use crate::scannerless::Pat as SPat;
 pub use proc_macro2::{
     Delimiter, Ident, LexError, Literal, Punct, Spacing, Span, TokenStream, TokenTree,
 };
+use std::fmt;
+use std::ops::Deref;
 use std::str::FromStr;
 
 pub type Context = crate::context::Context<Pat>;
@@ -46,7 +48,7 @@ pub fn builtin(cx: &mut Context) -> crate::Grammar {
 }
 
 #[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
-pub struct Pat(pub Vec<FlatTokenPat<String>>);
+pub struct Pat<Pats = Vec<FlatTokenPat<String>>>(pub Pats);
 
 impl FromStr for Pat {
     type Err = LexError;
@@ -72,6 +74,12 @@ impl From<&str> for Pat {
     }
 }
 
+impl<Pats> From<Pats> for Pat<Pats> {
+    fn from(pats: Pats) -> Self {
+        Pat(pats)
+    }
+}
+
 impl From<FlatTokenPat<String>> for Pat {
     fn from(pat: FlatTokenPat<String>) -> Self {
         Pat(vec![pat])
@@ -100,7 +108,7 @@ pub enum FlatToken {
     Literal(Literal),
 }
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum FlatTokenPat<S: AsRef<str>> {
     Delim(char),
     Ident(Option<S>),
@@ -111,6 +119,51 @@ pub enum FlatTokenPat<S: AsRef<str>> {
     Literal,
 }
 
+impl<S: AsRef<str>> fmt::Debug for FlatTokenPat<S> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            FlatTokenPat::Delim(c) | FlatTokenPat::Punct { ch: Some(c), .. } => {
+                write!(f, "\"{}\"", c)
+            }
+            FlatTokenPat::Ident(None) => f.write_str("IDENT"),
+            FlatTokenPat::Ident(Some(ident)) => write!(f, "\"{}\"", ident.as_ref()),
+            FlatTokenPat::Punct { ch: None, .. } => f.write_str("PUNCT"),
+            FlatTokenPat::Literal => f.write_str("LITERAL"),
+        }
+    }
+}
+
+// FIXME(eddyb) can't use `Pats: AsRef<[FlatTokenPat<S>]` as it doesn't constrain `S`.
+impl<S: AsRef<str>, Pats: Deref<Target = [FlatTokenPat<S>]>> fmt::Debug for Pat<Pats> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match &self.0[..] {
+            [] => f.write_str("\"\""),
+            [pat] => pat.fmt(f),
+            pats => {
+                let mut was_joint = true;
+                f.write_str("\"")?;
+                for pat in pats {
+                    if !was_joint {
+                        f.write_str(" ")?;
+                    }
+                    match pat {
+                        FlatTokenPat::Punct { ch: Some(c), joint } => {
+                            write!(f, "{}", c)?;
+                            was_joint = *joint == Some(true);
+                        }
+                        FlatTokenPat::Ident(Some(ident)) => {
+                            write!(f, "\"{}\"", ident.as_ref())?;
+                            was_joint = false;
+                        }
+                        _ => unreachable!(),
+                    }
+                }
+                f.write_str("\"")
+            }
+        }
+    }
+}
+
 impl FlatToken {
     pub fn span(&self) -> Span {
         match self {
diff --git a/src/proc_macro_input.rs b/src/proc_macro_input.rs
index 53d6fa2..f7a0c77 100644
--- a/src/proc_macro_input.rs
+++ b/src/proc_macro_input.rs
@@ -52,8 +52,8 @@ impl Input for TokenStream {
     }
 }
 
-impl InputMatch<&'static [FlatTokenPat<&'static str>]> for [FlatToken] {
-    fn match_left(&self, &pat: &&[FlatTokenPat<&str>]) -> Option<usize> {
+impl InputMatch<[FlatTokenPat<&'_ str>]> for [FlatToken] {
+    fn match_left(&self, pat: &[FlatTokenPat<&str>]) -> Option<usize> {
         if self
             .iter()
             .zip(pat)
@@ -66,7 +66,7 @@ impl InputMatch<&'static [FlatTokenPat<&'static str>]> for [FlatToken] {
             None
         }
     }
-    fn match_right(&self, &pat: &&[FlatTokenPat<&str>]) -> Option<usize> {
+    fn match_right(&self, pat: &[FlatTokenPat<&str>]) -> Option<usize> {
         if self
             .iter()
             .zip(pat)
diff --git a/src/scannerless.rs b/src/scannerless.rs
index 0f0edc3..4139177 100644
--- a/src/scannerless.rs
+++ b/src/scannerless.rs
@@ -1,15 +1,35 @@
 use crate::rule::{MatchesEmpty, MaybeKnown};
 use std::char;
+use std::fmt;
 use std::ops::{self, Bound, RangeBounds};
 
 pub type Context<S = String> = crate::context::Context<Pat<S>>;
 
-#[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
+#[derive(Copy, Clone, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Pat<S = String, C = char> {
     String(S),
     Range(C, C),
 }
 
+impl<S: fmt::Debug> fmt::Debug for Pat<S> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Pat::String(s) => s.fmt(f),
+            &Pat::Range(start, end) => {
+                if start != '\0' {
+                    start.fmt(f)?;
+                }
+                f.write_str("..")?;
+                if end != char::MAX {
+                    f.write_str("=")?;
+                    end.fmt(f)?;
+                }
+                Ok(())
+            }
+        }
+    }
+}
+
 impl<'a, C> From<&'a str> for Pat<&'a str, C> {
     fn from(s: &'a str) -> Self {
         Pat::String(s)