diff --git a/src/compiler.rs b/src/compiler.rs
index 71556ce..26893cf 100644
--- a/src/compiler.rs
+++ b/src/compiler.rs
@@ -1,12 +1,15 @@
 use std::{
-    any::{Any, TypeId}, collections::{BTreeMap, HashMap}, f64, fmt::Debug, str::FromStr
+    any::{Any, TypeId},
+    collections::{BTreeMap, HashMap},
+    f64,
+    fmt::Debug,
+    str::FromStr,
 };
 
 use cfg_if::cfg_if;
 use derive_new::new;
 use derive_wrapper::{AsRef, From};
 use fasteval::{Compiler as _, EvalNamespace, Evaler, Instruction, Slab};
-use lazy_static::lazy_static;
 use thiserror::Error;
 
 cfg_if! {
@@ -19,30 +22,19 @@ cfg_if! {
 
 #[derive(From, AsRef, Default)]
 #[cfg_attr(test, derive(Debug))]
-pub struct TokenVec<'a>(pub(crate) Vec<Box<dyn Token + 'a>>);
+pub struct TokenVec(pub(crate) Vec<Box<dyn Token>>);
 
 pub trait Type {
     fn type_id(&self) -> TypeId;
 }
 
-macro_rules! impl_type {
-    ($name:ty) => {
-        impl Type for $name {
-            fn type_id(&self) -> std::any::TypeId {
-                <Self as std::any::Any>::type_id(self)
-            }
-        }
-    };
-}
-
-macro_rules! impl_type_life {
-    ($name:ty) => {
-        impl Type for $name {
-            fn type_id(&self) -> TypeId {
-                <$name as Any>::type_id(&Default::default())
-            }
-        }
-    };
+impl<T> Type for T
+where
+    T: Default + 'static,
+{
+    fn type_id(&self) -> TypeId {
+        <Self as Any>::type_id(&Default::default())
+    }
 }
 
 #[cfg(not(test))]
@@ -56,7 +48,7 @@ pub trait Token: Debug + Type {
 }
 
 #[cfg(test)]
-impl PartialEq for TokenVec<'_> {
+impl PartialEq for TokenVec {
     fn eq(&self, other: &Self) -> bool {
         format!("{self:?}") == format!("{other:?}")
     }
@@ -66,8 +58,6 @@ impl PartialEq for TokenVec<'_> {
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub struct Silence;
 
-impl_type!(Silence);
-
 impl Token for Silence {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
         let mut next = context.render(None)?;
@@ -80,8 +70,6 @@ impl Token for Silence {
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub struct Marker;
 
-impl_type!(Marker);
-
 impl Token for Marker {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
         context.result.clear();
@@ -93,8 +81,6 @@ impl Token for Marker {
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub struct Note(pub u8);
 
-impl_type!(Note);
-
 impl Token for Note {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
         let mut next = context.render(Some(self.0))?;
@@ -107,20 +93,22 @@ impl Token for Note {
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub struct VariableChange(pub char, pub Expression);
 
-impl_type!(VariableChange);
+impl AsRef<VariableChange> for VariableChange {
+    fn as_ref(&self) -> &VariableChange {
+        self
+    }
+}
 
 impl Token for VariableChange {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
-        *context.get_mut(self.0)? = context.eval(&self.1)?;
+        *context.get_mut(self.0)? = context.eval(self.1.as_ref())?;
         Ok(context)
     }
 }
 
 #[derive(Default)]
 #[cfg_attr(test, derive(Debug, PartialEq))]
-pub struct Loop<'a>(pub LoopCount, pub TokenVec<'a>);
-
-impl_type_life!(Loop<'_>);
+pub struct Loop(pub LoopCount, pub TokenVec);
 
 #[cfg_attr(test, derive(Debug, PartialEq))]
 pub enum LoopCount {
@@ -134,7 +122,7 @@ impl Default for LoopCount {
     }
 }
 
-impl Token for Loop<'_> {
+impl Token for Loop {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
         let mut old_result = context.result.clone();
         let count = match self.0 {
@@ -157,11 +145,9 @@ impl Token for Loop<'_> {
 
 #[derive(Default)]
 #[cfg_attr(test, derive(Debug, PartialEq))]
-pub struct Tuplet<'a>(pub TokenVec<'a>);
+pub struct Tuplet(pub TokenVec);
 
-impl_type_life!(Tuplet<'_>);
-
-impl Token for Tuplet<'_> {
+impl Token for Tuplet {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
         let mut old_result = context.result.clone();
         context.result.clear();
@@ -194,22 +180,15 @@ impl Token for Tuplet<'_> {
     }
 }
 
+#[derive(new, Default)]
 #[cfg_attr(test, derive(Debug, PartialEq))]
-pub struct Slope<'a>(pub &'a VariableChange, pub TokenVec<'a>);
+pub struct Slope(pub VariableChange, pub TokenVec);
 
-lazy_static! {
-    static ref VARIABLE_CHANGE_DEFAULT: VariableChange = Default::default();
-}
-
-impl Type for Slope<'_> {
-    fn type_id(&self) -> TypeId {
-        <Slope as Any>::type_id(&Slope(&VARIABLE_CHANGE_DEFAULT, Default::default()))
-    }
-}
-
-impl Token for Slope<'_> {
+impl Token for Slope {
     fn apply(&self, mut context: Context) -> Result<Context, CompilerError> {
-        context.slopes.push((self.0.0, self.0.1.clone()));
+        context
+            .slopes
+            .push((self.0.as_ref().0, self.0.as_ref().1.as_ref().clone()));
         context = self
             .1
             .0
@@ -228,6 +207,12 @@ pub struct Expression {
     pub(crate) slab: Slab,
 }
 
+impl AsRef<Expression> for Expression {
+    fn as_ref(&self) -> &Expression {
+        self
+    }
+}
+
 impl Clone for Expression {
     fn clone(&self) -> Self {
         self.from
diff --git a/src/parser.rs b/src/parser.rs
index 2c909ef..9b64364 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -1,9 +1,6 @@
-use std::{
-    collections::{BTreeMap, HashMap},
-    fmt::Display,
-};
+use std::{borrow::Borrow, collections::BTreeMap, marker::PhantomData};
 
-use derive_builder::Builder;
+use derive_new::new;
 use fasteval::Evaler;
 use nom::{
     AsChar, Compare, Finish, IResult, Input, Parser as NomParser,
@@ -25,18 +22,35 @@ use crate::compiler::{
     VariableChange,
 };
 
-#[derive(Builder)]
-pub struct Parser<'n, 's, 'v, N: AsRef<str> + Clone> {
-    notes: &'n [N],
-    slopes: &'s HashMap<String, VariableChange>,
-    variables: &'v [char],
+#[derive(new)]
+pub struct Parser<N, NS, S, SS, SV, V>
+where
+    N: AsRef<[NS]>,
+    NS: AsRef<str>,
+    S: IntoIterator<Item = (SS, SV)>,
+    SS: AsRef<str>,
+    SV: Borrow<VariableChange>,
+    V: AsRef<[char]>,
+{
+    notes: N,
+    slopes: S,
+    variables: V,
+    phantom: PhantomData<(NS, SS)>,
 }
 
-impl<'a, 's, N: AsRef<str> + Clone> Parser<'_, 's, '_, N> {
+impl<'a, N, NS, S, SS, SV, V> Parser<N, NS, S, SS, SV, V>
+where
+    N: AsRef<[NS]>,
+    NS: AsRef<str>,
+    S: IntoIterator<Item = (SS, SV)> + Clone,
+    SS: AsRef<str>,
+    SV: Borrow<VariableChange>,
+    V: AsRef<[char]>,
+{
     pub fn parse_all(
         &self,
         input: &'a str,
-    ) -> Result<TokenVec<'s>, Error<nom_locate::LocatedSpan<&'a str>>> {
+    ) -> Result<TokenVec, Error<nom_locate::LocatedSpan<&'a str>>> {
         token_parser(self)
             .parse_complete(LocatedSpan::new(input))
             .finish()
@@ -44,14 +58,19 @@ impl<'a, 's, N: AsRef<str> + Clone> Parser<'_, 's, '_, N> {
     }
 }
 
-fn token_parser<'a, 's, I, N>(
-    parser: &Parser<'_, 's, '_, N>,
-) -> impl NomParser<I, Output = TokenVec<'s>, Error = nom::error::Error<I>>
+fn token_parser<'a, I, N, NS, S, SS, SV, V>(
+    parser: &Parser<N, NS, S, SS, SV, V>,
+) -> impl NomParser<I, Output = TokenVec, Error = nom::error::Error<I>>
 where
     I: Input + AsRef<str> + for<'z> nom::Compare<&'z str> + Copy,
     <I as Input>::Item: AsChar,
     <I as Input>::Item: PartialEq<char>,
-    N: AsRef<str> + Clone,
+    N: AsRef<[NS]>,
+    NS: AsRef<str>,
+    S: IntoIterator<Item = (SS, SV)> + Clone,
+    SS: AsRef<str>,
+    SV: Borrow<VariableChange>,
+    V: AsRef<[char]>,
 {
     let space_or_comment = || {
         value(
@@ -64,8 +83,8 @@ where
         alt((
             Silence::parser().map(into_box),
             Marker::parser().map(into_box),
-            Note::parser(parser.notes).map(into_box),
-            VariableChange::parser(parser.variables).map(into_box),
+            Note::parser(parser.notes.as_ref()).map(into_box),
+            VariableChange::parser(&parser.variables).map(into_box),
             Loop::parser(parser).map(into_box),
             Tuplet::parser(parser).map(into_box),
             Slope::parser(parser).map(into_box),
@@ -100,60 +119,87 @@ impl Marker {
 }
 
 impl Note {
-    fn parser<'n, N, I>(
-        notes: &'n [N],
-    ) -> impl NomParser<I, Output = Self, Error = nom::error::Error<I>>
+    fn parser<'a, N, NS, I>(
+        notes: N,
+    ) -> impl NomParser<I, Output = Self, Error = nom::error::Error<I>> + 'a
     where
-        N: AsRef<str> + Clone,
+        N: IntoIterator<Item = NS>,
+        NS: AsRef<str>,
         I: Input + for<'z> Compare<&'z str>,
     {
-        |input: I| {
-            let mut parsers: Vec<Box<dyn Fn(I) -> IResult<I, Self>>> = {
-                let mut sorted = notes.iter().enumerate().collect::<Vec<(usize, &N)>>();
-                sorted.sort_by_key(|(_, n)| n.as_ref().len());
-                sorted
-            }
-            .drain(..)
-            .rev()
-            .map(|(i, t)| {
-                Box::new(move |input: I| value(Note(i as u8), tag(t.clone().as_ref())).parse(input))
-                    as Box<dyn Fn(I) -> IResult<I, Self>>
-            })
-            .collect();
+        let notes = {
+            let mut sorted = notes
+                .into_iter()
+                .map(|s| s.as_ref().to_string())
+                .enumerate()
+                .collect::<Vec<_>>();
+            sorted.sort_by_key(|(_, n)| n.len());
+            sorted
+        };
+        move |input: I| {
+            let mut parsers: Vec<Box<dyn Fn(I) -> IResult<I, Self>>> = notes
+                .clone()
+                .drain(..)
+                .rev()
+                .map(|(i, t)| {
+                    Box::new(move |input: I| {
+                        value(Note(i as u8), tag(t.clone().as_ref())).parse(input)
+                    }) as Box<dyn Fn(I) -> IResult<I, Self>>
+                })
+                .collect();
             alt(parsers.as_mut_slice()).parse(input)
         }
     }
 }
 
 impl VariableChange {
-    fn parser<I>(variables: &[char]) -> impl Fn(I) -> IResult<I, Self>
+    fn parser<I, V>(variables: V) -> impl Fn(I) -> IResult<I, Self>
     where
         I: Input + AsRef<str> + Copy,
         <I as Input>::Item: AsChar,
+        V: AsRef<[char]>,
     {
         move |i: I| {
-            preceded(char('$'), one_of(variables))
-                .and(expression_parser(variables))
-                .map(|(name, change)| VariableChange(name, change))
-                .parse(i)
+            preceded(
+                char('$'),
+                one_of(variables.as_ref().iter().collect::<String>().as_str()),
+            )
+            .and(expression_parser(variables.as_ref()))
+            .map(|(name, change)| VariableChange(name, change))
+            .parse(i)
         }
     }
 }
 
-impl<'s> Loop<'s> {
-    fn parser<'n, 'v, I, N>(parser: &Parser<'n, 's, 'v, N>) -> impl Fn(I) -> IResult<I, Self>
+impl Loop {
+    fn parser<I, N, NS, S, SS, SV, V>(
+        parser: &Parser<N, NS, S, SS, SV, V>,
+    ) -> impl Fn(I) -> IResult<I, Self>
     where
         I: Input + AsRef<str> + for<'z> nom::Compare<&'z str> + Copy,
         <I as Input>::Item: AsChar,
         <I as Input>::Item: PartialEq<char>,
-        N: AsRef<str> + Clone,
+        N: AsRef<[NS]>,
+        NS: AsRef<str>,
+        S: IntoIterator<Item = (SS, SV)> + Clone,
+        SS: AsRef<str>,
+        SV: Borrow<VariableChange>,
+        V: AsRef<[char]>,
     {
-        |input| {
+        move |input| {
             delimited(
                 char('('),
                 opt(alt((
                     usize.map(LoopCount::Litteral),
-                    one_of(parser.variables).map(LoopCount::Variable),
+                    one_of(
+                        parser
+                            .variables
+                            .as_ref()
+                            .iter()
+                            .collect::<String>()
+                            .as_str(),
+                    )
+                    .map(LoopCount::Variable),
                 )))
                 .and(token_parser(parser)),
                 char(')'),
@@ -164,13 +210,20 @@ impl<'s> Loop<'s> {
     }
 }
 
-impl<'s> Tuplet<'s> {
-    fn parser<'n, 'v, I, N>(parser: &Parser<'n, 's, 'v, N>) -> impl Fn(I) -> IResult<I, Self>
+impl Tuplet {
+    fn parser<I, N, NS, S, SS, SV, V>(
+        parser: &Parser<N, NS, S, SS, SV, V>,
+    ) -> impl Fn(I) -> IResult<I, Self>
     where
         I: Input + for<'z> Compare<&'z str> + AsRef<str> + Copy,
         <I as Input>::Item: AsChar,
         <I as Input>::Item: PartialEq<char>,
-        N: AsRef<str> + Clone,
+        N: AsRef<[NS]>,
+        NS: AsRef<str>,
+        S: IntoIterator<Item = (SS, SV)> + Clone,
+        SS: AsRef<str>,
+        SV: Borrow<VariableChange>,
+        V: AsRef<[char]>,
     {
         |input| {
             delimited(char('['), token_parser(parser), char(']'))
@@ -180,54 +233,70 @@ impl<'s> Tuplet<'s> {
     }
 }
 
-impl<'s> Slope<'s> {
-    fn parser<'n, 'v, I, N>(parser: &Parser<'n, 's, 'v, N>) -> impl Fn(I) -> IResult<I, Self>
+impl Slope {
+    fn parser<'p, I, N, NS, S, SS, SV, V>(
+        parser: &'p Parser<N, NS, S, SS, SV, V>,
+    ) -> impl Fn(I) -> IResult<I, Self>
     where
         I: Input + for<'z> Compare<&'z str> + AsRef<str> + Copy,
         <I as Input>::Item: AsChar,
         <I as Input>::Item: PartialEq<char>,
-        N: AsRef<str> + Clone,
+        N: AsRef<[NS]>,
+        NS: AsRef<str>,
+        S: IntoIterator<Item = (SS, SV)> + Clone,
+        SS: AsRef<str>,
+        SV: Borrow<VariableChange>,
+        V: AsRef<[char]>,
     {
-        |input| {
-            let iter: std::iter::Rev<std::vec::IntoIter<(&'s String, &'s VariableChange)>> = {
+        move |input| {
+            let slopes = {
                 let mut vec = parser
                     .slopes
-                    .iter()
-                    .collect::<Vec<(&'s String, &'s VariableChange)>>();
+                    .clone()
+                    .into_iter()
+                    .map(|(s1, s2)| (s1.as_ref().to_string(), s2.borrow().clone()))
+                    .collect::<Vec<(String, VariableChange)>>();
                 vec.sort_by_key(|(name, _)| name.len());
                 vec
-            }
-            .into_iter()
-            .rev();
+            };
+            let iter: std::iter::Rev<std::vec::IntoIter<(String, VariableChange)>> =
+                slopes.into_iter().rev();
             delimited(
                 char('{'),
                 alt(iter
                     .map(|(k, v)| {
-                        Box::new(move |input: I| value(v, tag(k.as_str())).parse(input))
-                            as Box<dyn 's + Fn(I) -> IResult<I, &'s VariableChange>>
+                        Box::new(move |input: I| value(v.clone(), tag(k.as_str())).parse(input))
+                            as Box<dyn Fn(I) -> IResult<I, VariableChange>>
                     })
-                    .collect::<Vec<Box<dyn 's + Fn(I) -> IResult<I, &'s VariableChange>>>>()
+                    .collect::<Vec<Box<dyn Fn(I) -> IResult<I, VariableChange>>>>()
                     .as_mut_slice())
                 .and(token_parser(parser)),
                 char('}'),
             )
-            .map(|(i, v)| Self(i, v))
+            .map(|(i, v)| Self::new(i, v))
             .parse(input)
         }
     }
 }
 
 /// Will return the longest valid fasteval expression
-fn expression_parser<I: Input + AsRef<str> + Copy, C: Into<char> + Ord + Display>(
-    variables: &[C],
-) -> impl Fn(I) -> IResult<I, Expression> {
-    |input: I| {
+fn expression_parser<'v, I, V, C>(variables: V) -> impl 'v + Fn(I) -> IResult<I, Expression>
+where
+    I: Input + AsRef<str> + Copy,
+    V: IntoIterator<Item = C>,
+    C: Borrow<char>,
+{
+    let variables: Vec<(String, f64)> = variables
+        .into_iter()
+        .map(|v| (v.borrow().to_string(), 0.0))
+        .collect();
+    move |input: I| {
         take_while_map(|i: I| {
             i.as_ref().parse::<Expression>().ok().and_then(|e| {
                 e.instruction
                     .eval(
                         &e.slab,
-                        &mut BTreeMap::from_iter(variables.iter().map(|v| (v.to_string(), 0.0))),
+                        &mut BTreeMap::from_iter(variables.clone().drain(..)),
                     )
                     .ok()
                     .is_some()
@@ -261,9 +330,11 @@ where
 
 #[cfg(test)]
 mod tests {
+    use super::Parser;
+
     use std::collections::HashMap;
 
-    use nom::{IResult, Parser};
+    use nom::{IResult, Parser as _};
 
     use crate::{
         compiler::{
@@ -272,7 +343,31 @@ mod tests {
         parser::expression_parser,
     };
 
-    use super::ParserBuilder;
+    fn very_fancy_slope() -> VariableChange {
+        VariableChange('n', "1+1".parse().unwrap())
+    }
+
+    fn normal_slope() -> VariableChange {
+        VariableChange('n', "1".parse().unwrap())
+    }
+
+    fn parser_generator() -> Parser<
+        [&'static str; 3],
+        &'static str,
+        HashMap<String, VariableChange>,
+        String,
+        VariableChange,
+        [char; 1],
+    > {
+        Parser::new(
+            ["do", "ré", "mi"],
+            HashMap::from([
+                ("nor".to_string(), very_fancy_slope()),
+                ("normal".to_string(), normal_slope()),
+            ]),
+            ['n'],
+        )
+    }
 
     #[test]
     fn expression_parser_test() {
@@ -435,17 +530,9 @@ mod tests {
         let slopes = Default::default();
         fn parser_builder<'s>(
             slopes: &'s HashMap<String, VariableChange>,
-        ) -> impl Fn(&str) -> IResult<&str, Loop<'s>> {
+        ) -> impl Fn(&str) -> IResult<&str, Loop> {
             move |input: &str| {
-                Loop::parser(
-                    &ParserBuilder::create_empty()
-                        .notes(&["do", "ré", "mi"])
-                        .slopes(slopes)
-                        .variables(&['n'])
-                        .build()
-                        .unwrap(),
-                )
-                .parse(input)
+                Loop::parser(&Parser::new(["do", "ré", "mi"], slopes, ['n'])).parse(input)
             }
         }
         let parser = parser_builder(&slopes);
@@ -497,17 +584,9 @@ mod tests {
         let slopes = Default::default();
         fn parser_builder<'s>(
             slopes: &'s HashMap<String, VariableChange>,
-        ) -> impl Fn(&str) -> IResult<&str, Tuplet<'s>> {
+        ) -> impl Fn(&str) -> IResult<&str, Tuplet> {
             move |input: &str| {
-                Tuplet::parser(
-                    &ParserBuilder::create_empty()
-                        .notes(&["do", "ré", "mi"])
-                        .slopes(slopes)
-                        .variables(&['n'])
-                        .build()
-                        .unwrap(),
-                )
-                .parse(input)
+                Tuplet::parser(&Parser::new(["do", "ré", "mi"], slopes, ['n'])).parse(input)
             }
         }
         let parser = parser_builder(&slopes);
@@ -542,46 +621,30 @@ mod tests {
 
     #[test]
     fn slope() {
-        let normal = || VariableChange('n', "1".parse().unwrap());
-        let very_fancy = || VariableChange('n', "1+1".parse().unwrap());
-        let slopes = HashMap::from([
-            ("nor".to_string(), very_fancy()),
-            ("normal".to_string(), normal()),
-        ]);
-        fn parser_builder<'s>(
-            slopes: &'s HashMap<String, VariableChange>,
-        ) -> impl Fn(&str) -> IResult<&str, Slope<'s>> {
-            move |input: &str| {
-                Slope::parser(
-                    &ParserBuilder::create_empty()
-                        .notes(&["do", "ré", "mi"])
-                        .slopes(slopes)
-                        .variables(&['n'])
-                        .build()
-                        .unwrap(),
-                )
-                .parse(input)
-            }
-        }
-        let parser = parser_builder(&slopes);
-        let normal_value = normal();
-        let very_fancy_value = very_fancy();
+        let p = parser_generator();
+        let parser_builder = || Slope::parser(&p);
+        let parser = parser_builder();
+        let normal_value = normal_slope();
+        let very_fancy_value = very_fancy_slope();
         let mut working_cases = vec![
             (
                 "{normal.%}",
                 (
                     "",
                     Slope(
-                        &normal_value,
+                        normal_value.clone(),
                         TokenVec(vec![Box::new(Silence), Box::new(Marker)]),
                     ),
                 ),
             ),
-            ("{normal}", ("", Slope(&normal_value, TokenVec(vec![])))),
-            ("{nor}", ("", Slope(&very_fancy_value, TokenVec(vec![])))),
+            (
+                "{normal}",
+                ("", Slope(normal_value.clone(), TokenVec(vec![]))),
+            ),
+            ("{nor}", ("", Slope(very_fancy_value, TokenVec(vec![])))),
             (
                 "{normal do}f",
-                ("f", Slope(&normal_value, TokenVec(vec![Box::new(Note(0))]))),
+                ("f", Slope(normal_value, TokenVec(vec![Box::new(Note(0))]))),
             ),
         ];
         let mut not_working_cases = vec![