Include trailing newline in pretty print output

Along with this comes the decision to no longer track whitespace and
comments across desugarings in most cases. The main reason for this
decision is that not having to track whitespace simplifies the code and
reasoning necessary.

While implementing desugarings, I also realized that the current comment
model doesn't let me accurately track whitespace across desugarings. I'm
fairly sure I haven't yet found a good model for whitespace and
comments. Once I find one, adding pretty printing support for those
should hopefully be easy though.

src/ast/basic.rs

@@ -2,6 +2,8 @@ use std::fmt;
 
 use crate::span::{HasSpan, Span};
 
+use super::{TableConstr, TableConstrElem, TableLit, TableLitElem};
+
 #[derive(Clone)]
 pub enum Line {
     Empty,
@@ -37,17 +39,6 @@ impl Space {
             span,
         }
     }
-
-    pub fn then(mut self, other: Self) -> Self {
-        self.lines.extend(other.lines);
-        self.span = self.span.join(other.span);
-        self
-    }
-
-    pub fn then_line(mut self, line: Line) -> Self {
-        self.lines.push(line);
-        self
-    }
 }
 
 #[derive(Clone)]
@@ -78,21 +69,76 @@ impl HasSpan for Ident {
 }
 
 #[derive(Debug, Clone)]
-pub enum Separated<E, S1, S2> {
-    Empty(Span),
-    NonEmpty {
-        first_elem: E,
-        last_elems: Vec<(S1, E)>,
-        trailing: Option<S2>,
-        span: Span,
-    },
+pub struct BoundedSeparated<E> {
+    pub elems: Vec<(Space, E, Space)>,
+    pub trailing: Option<Space>,
+    pub span: Span,
 }
 
-impl<E, S1, S2> HasSpan for Separated<E, S1, S2> {
+impl<E> HasSpan for BoundedSeparated<E> {
     fn span(&self) -> Span {
-        match self {
-            Self::Empty(span) => *span,
-            Self::NonEmpty { span, .. } => *span,
-        }
+        self.span
+    }
+}
+
+impl<E> BoundedSeparated<E> {
+    pub fn new(span: Span) -> Self {
+        Self {
+            elems: vec![],
+            trailing: None,
+            span,
+        }
+    }
+
+    pub fn then(mut self, elem: E) -> Self {
+        self.elems
+            .push((Space::empty(self.span), elem, Space::empty(self.span)));
+        self
+    }
+
+    pub fn map<E2>(self, f: impl Fn(E) -> E2) -> BoundedSeparated<E2> {
+        let elems = self
+            .elems
+            .into_iter()
+            .map(|(s0, e, s1)| (s0, f(e), s1))
+            .collect::<Vec<_>>();
+
+        BoundedSeparated {
+            elems,
+            trailing: self.trailing,
+            span: self.span,
+        }
+    }
+
+    pub fn remove_map<E1, E2>(
+        self,
+        f: impl Fn(E) -> Result<E1, E2>,
+    ) -> (BoundedSeparated<E1>, Vec<(Space, E2, Space)>) {
+        let mut kept = vec![];
+        let mut removed = vec![];
+        for (s0, elem, s1) in self.elems {
+            match f(elem) {
+                Ok(elem) => kept.push((s0, elem, s1)),
+                Err(elem) => removed.push((s0, elem, s1)),
+            }
+        }
+        let new = BoundedSeparated {
+            elems: kept,
+            trailing: self.trailing,
+            span: self.span,
+        };
+        (new, removed)
+    }
+}
+
+impl BoundedSeparated<TableLitElem> {
+    pub fn table_lit(self) -> TableLit {
+        TableLit(self)
+    }
+}
+
+impl BoundedSeparated<TableConstrElem> {
+    pub fn table_constr(self) -> TableConstr {
+        TableConstr(self)
     }
 }

src/ast/call.rs

@@ -46,3 +46,38 @@ impl HasSpan for Call {
         }
     }
 }
+
+impl Call {
+    pub fn arg(base: Box<Expr>, arg: Box<Expr>, span: Span) -> Self {
+        Self::Arg {
+            expr: base,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            arg,
+            s2: Space::empty(span),
+            span,
+        }
+    }
+
+    pub fn no_arg(base: Box<Expr>, span: Span) -> Self {
+        Self::NoArg {
+            expr: base,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            span,
+        }
+    }
+
+    pub fn constr(base: Box<Expr>, constr: TableConstr, span: Span) -> Self {
+        Self::Constr {
+            expr: base,
+            s0: Space::empty(span),
+            constr,
+            span,
+        }
+    }
+
+    pub fn expr(self) -> Expr {
+        Expr::Call(self)
+    }
+}

src/ast/expr.rs

@@ -242,3 +242,9 @@ impl HasSpan for Expr {
         }
     }
 }
+
+impl Expr {
+    pub fn boxed(self) -> Box<Self> {
+        Box::new(self)
+    }
+}

src/ast/field.rs

@@ -67,3 +67,34 @@ impl HasSpan for Field {
         }
     }
 }
+
+impl Field {
+    pub fn access(base: Box<Expr>, index: Box<Expr>, span: Span) -> Self {
+        Self::Access {
+            expr: base,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            index,
+            s2: Space::empty(span),
+            span,
+        }
+    }
+
+    pub fn assign(base: Box<Expr>, index: Box<Expr>, value: Box<Expr>, span: Span) -> Self {
+        Self::Assign {
+            expr: base,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            index,
+            s2: Space::empty(span),
+            s3: Space::empty(span),
+            s4: Space::empty(span),
+            value,
+            span,
+        }
+    }
+
+    pub fn expr(self) -> Expr {
+        Expr::Field(self)
+    }
+}

src/ast/func_def.rs

@@ -99,3 +99,41 @@ impl HasSpan for FuncDef {
         }
     }
 }
+
+impl FuncDef {
+    pub fn anon_no_arg(body: Box<Expr>, span: Span) -> Self {
+        Self::AnonNoArg {
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            s2: Space::empty(span),
+            body,
+            span,
+        }
+    }
+
+    pub fn anon_arg(arg: Ident, body: Box<Expr>, span: Span) -> Self {
+        Self::AnonArg {
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            arg,
+            s2: Space::empty(span),
+            s3: Space::empty(span),
+            body,
+            span,
+        }
+    }
+
+    pub fn anon_destr(pattern: TablePattern, body: Box<Expr>, span: Span) -> Self {
+        Self::AnonDestr {
+            s0: Space::empty(span),
+            pattern,
+            s1: Space::empty(span),
+            body,
+            span,
+        }
+    }
+
+    pub fn expr(self) -> Expr {
+        Expr::FuncDef(self)
+    }
+}

src/ast/lit.rs

@@ -3,7 +3,7 @@ use std::fmt;
 use crate::builtin::Builtin;
 use crate::span::{HasSpan, Span};
 
-use super::{Expr, Ident, Separated, Space};
+use super::{BoundedSeparated, Expr, Ident, Space};
 
 #[derive(Clone)]
 pub enum NumLitStr {
@@ -93,6 +93,19 @@ pub struct StringLit {
     pub span: Span,
 }
 
+impl StringLit {
+    pub fn from_ident(ident: Ident) -> Self {
+        Self {
+            elems: vec![StringLitElem::Plain(ident.name)],
+            span: ident.span,
+        }
+    }
+
+    pub fn lit(self) -> Lit {
+        Lit::String(self)
+    }
+}
+
 impl HasSpan for StringLit {
     fn span(&self) -> Span {
         self.span
@@ -125,20 +138,31 @@ impl HasSpan for TableLitElem {
     }
 }
 
-/// `'{ a, foo: b }`
-///
-/// Structure: `'{ s0 elems s1 }`
-#[derive(Debug, Clone)]
-pub struct TableLit {
-    pub s0: Space,
-    pub elems: Separated<TableLitElem, (Space, Space), Space>,
-    pub s1: Space,
-    pub span: Span,
+impl TableLitElem {
+    pub fn named(name: Ident, value: Box<Expr>, span: Span) -> Self {
+        Self::Named {
+            name,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            value,
+            span,
+        }
+    }
 }
 
+/// `'{ a, foo: b }`
+#[derive(Debug, Clone)]
+pub struct TableLit(pub BoundedSeparated<TableLitElem>);
+
 impl HasSpan for TableLit {
     fn span(&self) -> Span {
-        self.span
+        self.0.span()
+    }
+}
+
+impl TableLit {
+    pub fn lit(self) -> Lit {
+        Lit::Table(self)
     }
 }
 
@@ -196,3 +220,9 @@ impl HasSpan for Lit {
         }
     }
 }
+
+impl Lit {
+    pub fn expr(self) -> Expr {
+        Expr::Lit(self)
+    }
+}

src/ast/program.rs

@@ -1,6 +1,6 @@
 use crate::span::{HasSpan, Span};
 
-use super::{Expr, Separated, Space, TableLitElem};
+use super::{BoundedSeparated, Expr, Space, TableLitElem};
 
 #[derive(Debug, Clone)]
 pub enum Program {
@@ -12,12 +12,10 @@ pub enum Program {
         span: Span,
     },
 
-    /// Structure: `s0 module s1 elems s2`
+    /// Structure: `s0 module elems`
     Module {
         s0: Space,
-        s1: Space,
-        elems: Separated<TableLitElem, (Space, Space), Space>,
-        s2: Space,
+        elems: BoundedSeparated<TableLitElem>,
         span: Span,
     },
 }

src/ast/table_constr.rs

@@ -1,6 +1,6 @@
 use crate::span::{HasSpan, Span};
 
-use super::{Expr, Separated, Space, TableLitElem};
+use super::{BoundedSeparated, Expr, Ident, Space, TableLitElem};
 
 #[derive(Debug, Clone)]
 pub enum TableConstrElem {
@@ -30,19 +30,28 @@ impl HasSpan for TableConstrElem {
     }
 }
 
-/// `{ a, b, foo: c, [d]: e }`
-///
-/// Structure: `{ s0 elems s1 }`
-#[derive(Debug, Clone)]
-pub struct TableConstr {
-    pub s0: Space,
-    pub elems: Separated<TableConstrElem, (Space, Space), Space>,
-    pub s1: Space,
-    pub span: Span,
+impl TableConstrElem {
+    pub fn positional(value: Box<Expr>) -> Self {
+        Self::Lit(TableLitElem::Positional(value))
+    }
+
+    pub fn named(name: Ident, value: Box<Expr>, span: Span) -> Self {
+        Self::Lit(TableLitElem::named(name, value, span))
+    }
 }
 
+/// `{ a, b, foo: c, [d]: e }`
+#[derive(Debug, Clone)]
+pub struct TableConstr(pub BoundedSeparated<TableConstrElem>);
+
 impl HasSpan for TableConstr {
     fn span(&self) -> Span {
-        self.span
+        self.0.span()
+    }
+}
+
+impl TableConstr {
+    pub fn expr(self) -> Expr {
+        Expr::TableConstr(self)
     }
 }

src/ast/table_destr.rs

@@ -1,6 +1,6 @@
 use crate::span::{HasSpan, Span};
 
-use super::{Expr, Ident, Separated, Space};
+use super::{BoundedSeparated, Expr, Ident, Space};
 
 // TODO Make table patterns recursive
 
@@ -34,16 +34,11 @@ impl HasSpan for TablePatternElem {
 ///
 /// Structure: `{ s0 elems s1 }`
 #[derive(Debug, Clone)]
-pub struct TablePattern {
-    pub s0: Space,
-    pub elems: Separated<TablePatternElem, (Space, Space), Space>,
-    pub s1: Space,
-    pub span: Span,
-}
+pub struct TablePattern(pub BoundedSeparated<TablePatternElem>);
 
 impl HasSpan for TablePattern {
     fn span(&self) -> Span {
-        self.span
+        self.0.span()
     }
 }
 
@@ -66,3 +61,26 @@ impl HasSpan for TableDestr {
         self.span
     }
 }
+
+impl TableDestr {
+    pub fn new(local: bool, pattern: TablePattern, value: Box<Expr>, span: Span) -> Self {
+        let local = if local {
+            Some(Space::empty(span))
+        } else {
+            None
+        };
+
+        Self {
+            local,
+            pattern,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            value,
+            span,
+        }
+    }
+
+    pub fn expr(self) -> Expr {
+        Expr::TableDestr(self)
+    }
+}

src/ast/var.rs

@@ -56,3 +56,54 @@ impl HasSpan for Var {
         }
     }
 }
+
+impl Var {
+    pub fn access(index: Box<Expr>, span: Span) -> Self {
+        Self::Access {
+            s0: Space::empty(span),
+            index,
+            s1: Space::empty(span),
+            span,
+        }
+    }
+
+    pub fn assign(local: bool, index: Box<Expr>, value: Box<Expr>, span: Span) -> Self {
+        let local = if local {
+            Some(Space::empty(span))
+        } else {
+            None
+        };
+
+        Self::Assign {
+            local,
+            s0: Space::empty(span),
+            index,
+            s1: Space::empty(span),
+            s2: Space::empty(span),
+            s3: Space::empty(span),
+            value,
+            span,
+        }
+    }
+
+    pub fn assign_ident(local: bool, name: Ident, value: Box<Expr>, span: Span) -> Self {
+        let local = if local {
+            Some(Space::empty(span))
+        } else {
+            None
+        };
+
+        Self::AssignIdent {
+            local,
+            name,
+            s0: Space::empty(span),
+            s1: Space::empty(span),
+            value,
+            span,
+        }
+    }
+
+    pub fn expr(self) -> Expr {
+        Expr::Var(self)
+    }
+}

src/builtin.rs

@@ -12,6 +12,21 @@ pub enum Builtin {
     Scope,
     Arg,
     Destructure,
+    Neg,
+    Not,
+    Mul,
+    Div,
+    Mod,
+    Add,
+    Sub,
+    Eq,
+    Ne,
+    Gt,
+    Ge,
+    Lt,
+    Le,
+    And,
+    Or,
 }
 
 impl fmt::Debug for Builtin {
@@ -26,6 +41,21 @@ impl fmt::Debug for Builtin {
             Self::Scope => write!(f, "'scope"),
             Self::Arg => write!(f, "'arg"),
             Self::Destructure => write!(f, "'destructure"),
+            Self::Neg => write!(f, "'neg"),
+            Self::Not => write!(f, "'not"),
+            Self::Mul => write!(f, "'mul"),
+            Self::Div => write!(f, "'div"),
+            Self::Mod => write!(f, "'mod"),
+            Self::Add => write!(f, "'add"),
+            Self::Sub => write!(f, "'sub"),
+            Self::Eq => write!(f, "'eq"),
+            Self::Ne => write!(f, "'ne"),
+            Self::Gt => write!(f, "'gt"),
+            Self::Ge => write!(f, "'ge"),
+            Self::Lt => write!(f, "'lt"),
+            Self::Le => write!(f, "'le"),
+            Self::And => write!(f, "'and"),
+            Self::Or => write!(f, "'or"),
         }
     }
 }

src/desugar.rs

@@ -2,6 +2,9 @@ mod basic;
 mod call;
 mod expr;
 mod field;
+mod func_def;
 mod lit;
 mod program;
+mod table_constr;
+mod table_destr;
 mod var;

src/desugar/basic.rs

@@ -1,36 +1,24 @@
-use crate::ast::Separated;
+use crate::ast::BoundedSeparated;
 
-impl<E, S1, S2> Separated<E, S1, S2> {
-    pub fn desugar_elem(self, desugar_elem: impl Fn(E) -> (E, bool)) -> (Self, bool) {
-        match self {
-            Self::Empty(span) => (Self::Empty(span), false),
-
-            Self::NonEmpty {
-                first_elem,
-                last_elems,
-                trailing,
-                span,
-            } => {
-                let (new_first_elem, mut desugared) = desugar_elem(first_elem);
-                let mut new_last_elems = vec![];
-                for (separator, elem) in last_elems {
-                    if desugared {
-                        new_last_elems.push((separator, elem));
-                    } else {
-                        let (elem, elem_desugared) = desugar_elem(elem);
-                        desugared = desugared || elem_desugared;
-                        new_last_elems.push((separator, elem));
-                    }
-                }
-
-                let new = Self::NonEmpty {
-                    first_elem: new_first_elem,
-                    last_elems: new_last_elems,
-                    trailing,
-                    span,
-                };
-                (new, desugared)
+impl<E> BoundedSeparated<E> {
+    pub fn desugar(self, desugar_elem: impl Fn(E) -> (E, bool)) -> (Self, bool) {
+        let mut desugared = false;
+        let mut elems = vec![];
+        for (s0, elem, s1) in self.elems {
+            if desugared {
+                elems.push((s0, elem, s1));
+            } else {
+                let (elem, elem_desugared) = desugar_elem(elem);
+                desugared = desugared || elem_desugared;
+                elems.push((s0, elem, s1));
             }
         }
+
+        let new = Self {
+            elems,
+            trailing: self.trailing,
+            span: self.span,
+        };
+        (new, desugared)
     }
 }

src/desugar/call.rs

@@ -1,4 +1,4 @@
-use crate::ast::{Call, Expr, Ident, Lit, Separated, Space, TableLit, TableLitElem};
+use crate::ast::{BoundedSeparated, Call, Expr, Ident, Lit, TableLitElem};
 
 // TODO Add span for just the parentheses to ast, or limit span to parentheses
 
@@ -7,74 +7,37 @@ impl Call {
         match self {
             Self::Arg {
                 expr,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 arg,
-                s2,
+                s2: _,
                 span,
             } => {
-                // `expr s0 ( s1 arg s2 )`
-                // -> `'{ s0 call: expr, arg: s1 arg s2 }`
-                let call = TableLitElem::Named {
-                    name: Ident::new("call", span),
-                    s0: Space::empty(span),
-                    s1: Space::empty(span),
-                    value: expr,
-                    span,
-                };
-                let arg = TableLitElem::Named {
-                    name: Ident::new("arg", span),
-                    s0: Space::empty(span),
-                    s1,
-                    value: arg,
-                    span,
-                };
-                let elems = Separated::NonEmpty {
-                    first_elem: call,
-                    last_elems: vec![((Space::empty(span), Space::empty(span)), arg)],
-                    trailing: None,
-                    span,
-                };
-                let new = Expr::Lit(Lit::Table(TableLit {
-                    s0,
-                    elems,
-                    s1: s2,
-                    span,
-                }));
-                (new, true)
+                let new = BoundedSeparated::new(span)
+                    .then(TableLitElem::named(Ident::new("call", span), expr, span))
+                    .then(TableLitElem::named(Ident::new("arg", span), arg, span))
+                    .table_lit();
+                (new.lit().expr(), true)
             }
 
-            Self::NoArg { expr, s0, s1, span } => {
-                // `expr s0 ( s1 )`
-                // -> `expr s0 ( s1 nil )`
-                let new = Expr::Call(Self::Arg {
-                    expr,
-                    s0,
-                    s1,
-                    arg: Box::new(Expr::Lit(Lit::Nil(span))),
-                    s2: Space::empty(span),
-                    span,
-                });
-                (new, true)
+            Self::NoArg {
+                expr,
+                s0: _,
+                s1: _,
+                span,
+            } => {
+                let new = Self::arg(expr, Lit::Nil(span).expr().boxed(), span);
+                (new.expr(), true)
             }
 
             Self::Constr {
                 expr,
-                s0,
+                s0: _,
                 constr,
                 span,
             } => {
-                // `expr s0 {..}`
-                // -> `expr s0 ( {..} )`
-                let new = Expr::Call(Self::Arg {
-                    expr,
-                    s0,
-                    s1: Space::empty(span),
-                    arg: Box::new(Expr::TableConstr(constr)),
-                    s2: Space::empty(span),
-                    span,
-                });
-                (new, true)
+                let new = Self::arg(expr, constr.expr().boxed(), span);
+                (new.expr(), true)
             }
         }
     }

src/desugar/expr.rs

@@ -1,84 +1,78 @@
-use crate::ast::Expr;
+use crate::ast::{BinOp, BoundedSeparated, Call, Expr, Lit, TableConstrElem};
+use crate::builtin::Builtin;
 
 impl Expr {
     pub fn desugar(self) -> (Self, bool) {
         match self {
             Self::Lit(lit) => {
                 let (lit, desugared) = lit.desugar();
-                (Self::Lit(lit), desugared)
+                (lit.expr(), desugared)
             }
 
             Self::Call(call) => call.desugar(),
             Self::Field(field) => field.desugar(),
             Self::Var(var) => var.desugar(),
-
-            Self::TableConstr(constr) => (Self::TableConstr(constr), false), // TODO Implement
-            Self::TableDestr(destr) => (Self::TableDestr(destr), false),     // TODO Implement
-            Self::FuncDef(def) => (Self::FuncDef(def), false),               // TODO Implement
+            Self::TableConstr(constr) => constr.desugar(),
+            Self::TableDestr(destr) => destr.desugar(),
+            Self::FuncDef(def) => def.desugar(),
 
             Self::Paren {
-                s0,
+                s0: _,
                 inner,
-                s1,
-                span,
-            } => (
-                Self::Paren {
-                    s0,
-                    inner,
-                    s1,
-                    span,
-                },
-                false,
-            ), // TODO Implement
+                s1: _,
+                span: _,
+            } => (*inner, true),
 
             Self::Neg {
                 minus,
-                s0,
+                s0: _,
                 expr,
                 span,
-            } => (
-                Self::Neg {
-                    minus,
-                    s0,
-                    expr,
-                    span,
-                },
-                false,
-            ), // TODO Implement
+            } => {
+                let new = Call::arg(Lit::Builtin(Builtin::Neg, minus).expr().boxed(), expr, span);
+                (new.expr(), true)
+            }
 
             Self::Not {
                 not,
-                s0,
+                s0: _,
                 expr,
                 span,
-            } => (
-                Self::Not {
-                    not,
-                    s0,
-                    expr,
-                    span,
-                },
-                false,
-            ), // TODO Implement
+            } => {
+                let new = Call::arg(Lit::Builtin(Builtin::Not, not).expr().boxed(), expr, span);
+                (new.expr(), true)
+            }
 
             Self::BinOp {
                 left,
-                s0,
+                s0: _,
                 op,
-                s1,
+                s1: _,
                 right,
                 span,
-            } => (
-                Self::BinOp {
-                    left,
-                    s0,
-                    op,
-                    s1,
-                    right,
-                    span,
-                },
-                false,
-            ), // TODO Implement
+            } => {
+                let builtin = match op {
+                    BinOp::Mul => Builtin::Mul,
+                    BinOp::Div => Builtin::Div,
+                    BinOp::Mod => Builtin::Mod,
+                    BinOp::Add => Builtin::Add,
+                    BinOp::Sub => Builtin::Sub,
+                    BinOp::Eq => Builtin::Eq,
+                    BinOp::Neq => Builtin::Ne,
+                    BinOp::Gt => Builtin::Gt,
+                    BinOp::Ge => Builtin::Ge,
+                    BinOp::Lt => Builtin::Lt,
+                    BinOp::Le => Builtin::Le,
+                    BinOp::And => Builtin::And,
+                    BinOp::Or => Builtin::Or,
+                };
+                let constr = BoundedSeparated::new(span)
+                    .then(TableConstrElem::positional(left))
+                    .then(TableConstrElem::positional(right))
+                    .table_constr();
+                let new = Call::constr(Lit::Builtin(builtin, span).expr().boxed(), constr, span);
+                (new.expr(), true)
+            }
         }
     }
 }

src/desugar/field.rs

@@ -1,7 +1,4 @@
-use crate::ast::{
-    Call, Expr, Field, Line, Lit, Separated, Space, StringLit, StringLitElem, TableConstr,
-    TableConstrElem, TableLitElem,
-};
+use crate::ast::{BoundedSeparated, Call, Expr, Field, Lit, StringLit, TableConstrElem};
 use crate::builtin::Builtin;
 
 impl Field {
@@ -9,133 +6,80 @@ impl Field {
         match self {
             Self::Access {
                 expr,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 index,
-                s2,
+                s2: _,
                 span,
             } => {
-                // ` expr s0 [ s1 index s2 ]`
-                // -> `'get s0 { expr, s1 index s2 }`
-                let elems = Separated::NonEmpty {
-                    first_elem: TableConstrElem::Lit(TableLitElem::Positional(expr)),
-                    last_elems: vec![(
-                        (Space::empty(span), s1),
-                        TableConstrElem::Lit(TableLitElem::Positional(index)),
-                    )],
-                    trailing: None,
-                    span,
-                };
-                let constr = TableConstr {
-                    s0: Space::empty(span),
-                    elems,
-                    s1: s2,
-                    span,
-                };
-                let new = Expr::Call(Call::Constr {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Get, span))),
-                    s0,
+                let constr = BoundedSeparated::new(span)
+                    .then(TableConstrElem::positional(expr))
+                    .then(TableConstrElem::positional(index))
+                    .table_constr();
+                let new = Call::constr(
+                    Lit::Builtin(Builtin::Get, span).expr().boxed(),
                     constr,
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
 
             Self::Assign {
                 expr,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 index,
-                s2,
-                s3,
-                s4,
+                s2: _,
+                s3: _,
+                s4: _,
                 value,
                 span,
             } => {
-                // `expr s0 [ s1 index s2 ] s3 = s4 value`
-                // -> `'set s0 { expr, s1 index s2, s3 s4 value }`
-                let elems = Separated::NonEmpty {
-                    first_elem: TableConstrElem::Lit(TableLitElem::Positional(expr)),
-                    last_elems: vec![
-                        (
-                            (Space::empty(span), s1),
-                            TableConstrElem::Lit(TableLitElem::Positional(index)),
-                        ),
-                        (
-                            (s2, s3.then_line(Line::Empty).then(s4)),
-                            TableConstrElem::Lit(TableLitElem::Positional(value)),
-                        ),
-                    ],
-                    trailing: None,
-                    span,
-                };
-                let constr = TableConstr {
-                    s0: Space::empty(span),
-                    elems,
-                    s1: Space::empty(span),
-                    span,
-                };
-                let new = Expr::Call(Call::Constr {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Set, span))),
-                    s0,
+                let constr = BoundedSeparated::new(span)
+                    .then(TableConstrElem::positional(expr))
+                    .then(TableConstrElem::positional(index))
+                    .then(TableConstrElem::positional(value))
+                    .table_constr();
+                let new = Call::constr(
+                    Lit::Builtin(Builtin::Set, span).expr().boxed(),
                     constr,
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
 
             Self::AccessIdent {
                 expr,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 ident,
                 span,
             } => {
-                // `expr s0 . s1 ident´
-                // -> `expr s0 [ s1 ident_str ]`
-                let ident_str = Expr::Lit(Lit::String(StringLit {
-                    elems: vec![StringLitElem::Plain(ident.name)],
-                    span: ident.span,
-                }));
-                let new = Expr::Field(Self::Access {
+                let new = Self::access(
                     expr,
-                    s0,
-                    s1,
-                    index: Box::new(ident_str),
-                    s2: Space::empty(span),
+                    StringLit::from_ident(ident).lit().expr().boxed(),
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
 
             Self::AssignIdent {
                 expr,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 ident,
-                s2,
-                s3,
+                s2: _,
+                s3: _,
                 value,
                 span,
             } => {
-                // `expr s0 . s1 ident s2 = s3 value`
-                // -> `expr s0 [ s1 ident_str ] s2 = s3 value`
-                let ident_str = Expr::Lit(Lit::String(StringLit {
-                    elems: vec![StringLitElem::Plain(ident.name)],
-                    span: ident.span,
-                }));
-                let new = Expr::Field(Self::Assign {
+                let new = Self::assign(
                     expr,
-                    s0,
-                    s1,
-                    index: Box::new(ident_str),
-                    s2: Space::empty(span),
-                    s3: s2,
-                    s4: s3,
+                    StringLit::from_ident(ident).lit().expr().boxed(),
                     value,
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
         }
     }

src/desugar/func_def.rs

@@ -0,0 +1,128 @@
+use crate::ast::{
+    BoundedSeparated, Call, Expr, FuncDef, Ident, Lit, Space, TableConstrElem, TableDestr,
+    TableLitElem, Var,
+};
+use crate::builtin::Builtin;
+
+impl FuncDef {
+    pub fn desugar(self) -> (Expr, bool) {
+        match self {
+            Self::AnonNoArg {
+                s0: _,
+                s1: _,
+                s2: _,
+                body,
+                span,
+            } => {
+                let quote = BoundedSeparated::new(span)
+                    .then(TableLitElem::named(Ident::new("quote", span), body, span))
+                    .table_lit();
+                let scope = Call::no_arg(Lit::Builtin(Builtin::Scope, span).expr().boxed(), span);
+                let new = BoundedSeparated::new(span)
+                    .then(TableConstrElem::positional(Box::new(quote.lit().expr())))
+                    .then(TableConstrElem::named(
+                        Ident::new("scope", span),
+                        scope.expr().boxed(),
+                        span,
+                    ))
+                    .table_constr();
+                (new.expr(), true)
+            }
+
+            Self::AnonArg {
+                s0: _,
+                s1: _,
+                arg,
+                s2: _,
+                s3: _,
+                body,
+                span,
+            } => {
+                let arg_call = Call::no_arg(Lit::Builtin(Builtin::Arg, span).expr().boxed(), span);
+                let arg_assign = Var::assign_ident(true, arg, arg_call.expr().boxed(), span);
+                let body = BoundedSeparated::new(span)
+                    .then(TableLitElem::Positional(arg_assign.expr().boxed()))
+                    .then(TableLitElem::Positional(body))
+                    .table_lit();
+                let new = Self::AnonNoArg {
+                    s0: Space::empty(span),
+                    s1: Space::empty(span),
+                    s2: Space::empty(span),
+                    body: body.lit().expr().boxed(),
+                    span,
+                };
+                (new.expr(), true)
+            }
+
+            Self::AnonDestr {
+                s0: _,
+                pattern,
+                s1: _,
+                body,
+                span,
+            } => {
+                let arg_call = Call::no_arg(Lit::Builtin(Builtin::Arg, span).expr().boxed(), span);
+                let arg_destr = TableDestr::new(true, pattern, arg_call.expr().boxed(), span);
+                let body = BoundedSeparated::new(span)
+                    .then(TableLitElem::Positional(arg_destr.expr().boxed()))
+                    .then(TableLitElem::Positional(body))
+                    .table_lit();
+                let new = Self::AnonNoArg {
+                    s0: Space::empty(span),
+                    s1: Space::empty(span),
+                    s2: Space::empty(span),
+                    body: body.lit().expr().boxed(),
+                    span,
+                };
+                (new.expr(), true)
+            }
+
+            Self::NamedNoArg {
+                local,
+                s0: _,
+                name,
+                s1: _,
+                s2: _,
+                s3: _,
+                body,
+                span,
+            } => {
+                let anon = Self::anon_no_arg(body, span);
+                let new = Var::assign_ident(local.is_some(), name, anon.expr().boxed(), span);
+                (new.expr(), true)
+            }
+
+            Self::NamedArg {
+                local,
+                s0: _,
+                name,
+                s1: _,
+                s2: _,
+                arg,
+                s3: _,
+                s4: _,
+                body,
+                span,
+            } => {
+                let anon = Self::anon_arg(arg, body, span);
+                let new = Var::assign_ident(local.is_some(), name, anon.expr().boxed(), span);
+                (new.expr(), true)
+            }
+
+            Self::NamedDestr {
+                local,
+                s0: _,
+                name,
+                s1: _,
+                pattern,
+                s2: _,
+                body,
+                span,
+            } => {
+                let anon = Self::anon_destr(pattern, body, span);
+                let new = Var::assign_ident(local.is_some(), name, anon.expr().boxed(), span);
+                (new.expr(), true)
+            }
+        }
+    }
+}

src/desugar/lit.rs

@@ -1,11 +1,11 @@
-use crate::ast::{Lit, TableLit, TableLitElem};
+use crate::ast::{Expr, Lit, TableLit, TableLitElem};
 
 impl TableLitElem {
     pub fn desugar(self) -> (Self, bool) {
         match self {
             Self::Positional(expr) => {
                 let (expr, desugared) = expr.desugar();
-                (Self::Positional(Box::new(expr)), desugared)
+                (Self::Positional(expr.boxed()), desugared)
             }
 
             Self::Named {
@@ -20,7 +20,7 @@ impl TableLitElem {
                     name,
                     s0,
                     s1,
-                    value: Box::new(value),
+                    value: value.boxed(),
                     span,
                 };
                 (new, desugared)
@@ -31,21 +31,18 @@ impl TableLitElem {
 
 impl TableLit {
     pub fn desugar(self) -> (Self, bool) {
-        let Self {
-            s0,
-            elems,
-            s1,
-            span,
-        } = self;
-
-        let (elems, desugared) = elems.desugar_elem(|e| e.desugar());
-        let new = Self {
-            s0,
-            elems,
-            s1,
-            span,
-        };
-        (new, desugared)
+        let (elems, removed) = self.0.remove_map(|e| match e {
+            TableLitElem::Named { value, .. } if matches!(*value, Expr::Lit(Lit::Nil(_))) => {
+                Err(())
+            }
+            e => Ok(e),
+        });
+        if removed.is_empty() {
+            let (elems, desugared) = elems.desugar(|e| e.desugar());
+            (elems.table_lit(), desugared)
+        } else {
+            (elems.table_lit(), true)
+        }
     }
 }
 
@@ -54,7 +51,7 @@ impl Lit {
         match self {
             Self::Table(table) => {
                 let (table, desugared) = table.desugar();
-                (Self::Table(table), desugared)
+                (table.lit(), desugared)
             }
 
             lit => (lit, false),

src/desugar/program.rs

@@ -1,4 +1,4 @@
-use crate::ast::{Expr, Lit, Program, Space, TableLit};
+use crate::ast::{Program, Space};
 
 impl Program {
     pub fn desugar(self) -> (Self, bool) {
@@ -9,24 +9,12 @@ impl Program {
                 (new, desugared)
             }
 
-            Self::Module {
-                s0,
-                s1,
-                elems,
-                s2,
-                span,
-            } => {
-                // `s0 module s1 elems s2`
-                // -> `s0 '{ s1 elems s2 } empty`
-                let table = TableLit {
-                    s0: s1,
-                    elems,
-                    s1: s2,
-                    span,
-                };
+            Self::Module { s0, elems, span } => {
+                // `s0 module elems`
+                // -> `s0 table`
                 let new = Self::Expr {
                     s0,
-                    expr: Expr::Lit(Lit::Table(table)),
+                    expr: elems.table_lit().lit().expr(),
                     s1: Space::empty(span),
                     span,
                 };

src/desugar/table_constr.rs

@@ -0,0 +1,39 @@
+use crate::ast::{
+    BoundedSeparated, Expr, Field, Ident, TableConstr, TableConstrElem, TableLitElem,
+};
+use crate::span::HasSpan;
+
+impl TableConstr {
+    pub fn desugar(self) -> (Expr, bool) {
+        let span = self.span();
+
+        let (elems, setters) = self.0.remove_map(|e| match e {
+            TableConstrElem::Lit(lit) => Ok(lit),
+            TableConstrElem::Indexed {
+                s0: _,
+                index,
+                s1: _,
+                s2: _,
+                s3: _,
+                value,
+                span,
+            } => Err((index, value, span)),
+        });
+
+        let mut expr = BoundedSeparated::new(span)
+            .then(TableLitElem::named(
+                Ident::new("raw", span),
+                elems.table_lit().lit().expr().boxed(),
+                span,
+            ))
+            .table_lit()
+            .lit()
+            .expr();
+
+        for (_, (index, value, span), _) in setters {
+            expr = Field::assign(expr.boxed(), index, value, span).expr();
+        }
+
+        (expr, true)
+    }
+}

src/desugar/table_destr.rs

@@ -0,0 +1,63 @@
+use crate::ast::{
+    BoundedSeparated, Call, Expr, Ident, Lit, StringLit, TableConstr, TableConstrElem, TableDestr,
+    TableLitElem, TablePattern, TablePatternElem,
+};
+use crate::builtin::Builtin;
+
+fn pattern_to_constr(pattern: TablePattern) -> TableConstr {
+    pattern
+        .0
+        .map(|e| match e {
+            TablePatternElem::Positional(ident) => {
+                TableConstrElem::positional(StringLit::from_ident(ident).lit().expr().boxed())
+            }
+
+            TablePatternElem::Named {
+                name,
+                s0,
+                s1,
+                ident,
+                span,
+            } => TableConstrElem::Lit(TableLitElem::Named {
+                name,
+                s0,
+                s1,
+                value: StringLit::from_ident(ident).lit().expr().boxed(),
+                span,
+            }),
+        })
+        .table_constr()
+}
+
+impl TableDestr {
+    pub fn desugar(self) -> (Expr, bool) {
+        let Self {
+            local,
+            pattern,
+            s0: _,
+            s1: _,
+            value,
+            span,
+        } = self;
+
+        let mut constr = BoundedSeparated::new(span)
+            .then(TableConstrElem::positional(
+                pattern_to_constr(pattern).expr().boxed(),
+            ))
+            .then(TableConstrElem::positional(value));
+        if local.is_some() {
+            constr = constr.then(TableConstrElem::named(
+                Ident::new("local", span),
+                Lit::Bool(true, span).expr().boxed(),
+                span,
+            ));
+        }
+
+        let new = Call::constr(
+            Lit::Builtin(Builtin::Destructure, span).expr().boxed(),
+            constr.table_constr(),
+            span,
+        );
+        (new.expr(), true)
+    }
+}

src/desugar/var.rs

@@ -1,7 +1,4 @@
-use crate::ast::{
-    Call, Expr, Field, Line, Lit, Separated, Space, StringLit, StringLitElem, TableConstr,
-    TableConstrElem, TableLitElem, Var,
-};
+use crate::ast::{BoundedSeparated, Call, Expr, Field, Lit, StringLit, TableConstrElem, Var};
 use crate::builtin::Builtin;
 use crate::span::HasSpan;
 
@@ -9,152 +6,76 @@ impl Var {
     pub fn desugar(self) -> (Expr, bool) {
         match self {
             Self::Access {
-                s0,
+                s0: _,
                 index,
-                s1,
+                s1: _,
                 span,
             } => {
-                // `[ s0 index s1 ]`
-                // -> `'scope()[ s0 index s1 ]`
-                let scope = Expr::Call(Call::NoArg {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Scope, span))),
-                    s0: Space::empty(span),
-                    s1: Space::empty(span),
-                    span,
-                });
-                let new = Expr::Field(Field::Access {
-                    expr: Box::new(scope),
-                    s0: Space::empty(span),
-                    s1: s0,
-                    index,
-                    s2: s1,
-                    span,
-                });
-                (new, true)
+                let scope = Call::no_arg(Lit::Builtin(Builtin::Scope, span).expr().boxed(), span);
+                let new = Field::access(scope.expr().boxed(), index, span);
+                (new.expr(), true)
             }
 
             Self::Assign {
                 local: None,
-                s0,
+                s0: _,
                 index,
-                s1,
-                s2,
-                s3,
+                s1: _,
+                s2: _,
+                s3: _,
                 value,
                 span,
             } => {
-                // `[ s0 index s1 ] s2 = s3 value`
-                // -> `'scope()[ s0 index s1 ] s2 = s3 value`
-                let scope = Expr::Call(Call::NoArg {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Scope, span))),
-                    s0: Space::empty(span),
-                    s1: Space::empty(span),
-                    span,
-                });
-                let new = Expr::Field(Field::Assign {
-                    expr: Box::new(scope),
-                    s0: Space::empty(span),
-                    s1: s0,
-                    index,
-                    s2: s1,
-                    s3: s2,
-                    s4: s3,
-                    value,
-                    span,
-                });
-                (new, true)
+                let scope = Call::no_arg(Lit::Builtin(Builtin::Scope, span).expr().boxed(), span);
+                let new = Field::assign(scope.expr().boxed(), index, value, span);
+                (new.expr(), true)
             }
 
             Self::Assign {
-                local: Some(local),
-                s0,
+                local: Some(_),
+                s0: _,
                 index,
-                s1,
-                s2,
-                s3,
+                s1: _,
+                s2: _,
+                s3: _,
                 value,
                 span,
             } => {
-                // `local [ s0 index s1 ] s2 = s3 value`
-                // --> `'setraw { 'scope(), local s0 index s1, s2 s3 value }`
-                let scope = Expr::Call(Call::NoArg {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::Scope, span))),
-                    s0: Space::empty(span),
-                    s1: Space::empty(span),
-                    span,
-                });
-                let elems = Separated::NonEmpty {
-                    first_elem: TableConstrElem::Lit(TableLitElem::Positional(Box::new(scope))),
-                    last_elems: vec![
-                        (
-                            (Space::empty(span), local.then_line(Line::Empty).then(s0)),
-                            TableConstrElem::Lit(TableLitElem::Positional(index)),
-                        ),
-                        (
-                            (s1, s2.then_line(Line::Empty).then(s3)),
-                            TableConstrElem::Lit(TableLitElem::Positional(value)),
-                        ),
-                    ],
-                    trailing: None,
-                    span,
-                };
-                let constr = TableConstr {
-                    s0: Space::empty(span),
-                    elems,
-                    s1: Space::empty(span),
-                    span,
-                };
-                let new = Expr::Call(Call::Constr {
-                    expr: Box::new(Expr::Lit(Lit::Builtin(Builtin::SetRaw, span))),
-                    s0: Space::empty(span),
+                let scope = Call::no_arg(Lit::Builtin(Builtin::Scope, span).expr().boxed(), span);
+                let constr = BoundedSeparated::new(span)
+                    .then(TableConstrElem::positional(scope.expr().boxed()))
+                    .then(TableConstrElem::positional(index))
+                    .then(TableConstrElem::positional(value))
+                    .table_constr();
+                let new = Call::constr(
+                    Lit::Builtin(Builtin::SetRaw, span).expr().boxed(),
                     constr,
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
 
             Self::AccessIdent(name) => {
-                // `name`
-                // -> `[ name_str ]`
                 let span = name.span();
-                let name_str = Expr::Lit(Lit::String(StringLit {
-                    elems: vec![StringLitElem::Plain(name.name)],
-                    span,
-                }));
-                let new = Expr::Var(Self::Access {
-                    s0: Space::empty(span),
-                    index: Box::new(name_str),
-                    s1: Space::empty(span),
-                    span,
-                });
-                (new, true)
+                let new = Self::access(StringLit::from_ident(name).lit().expr().boxed(), span);
+                (new.expr(), true)
             }
 
             Self::AssignIdent {
                 local,
                 name,
-                s0,
-                s1,
+                s0: _,
+                s1: _,
                 value,
                 span,
             } => {
-                // `local name s0 = s1 value`
-                // -> `local [ name_str ] s0 = s1 value`
-                let name_str = Expr::Lit(Lit::String(StringLit {
-                    elems: vec![StringLitElem::Plain(name.name)],
-                    span: name.span,
-                }));
-                let new = Expr::Var(Self::Assign {
-                    local,
-                    s0: Space::empty(span),
-                    index: Box::new(name_str),
-                    s1: Space::empty(span),
-                    s2: s0,
-                    s3: s1,
+                let new = Self::assign(
+                    local.is_some(),
+                    StringLit::from_ident(name).lit().expr().boxed(),
                     value,
                     span,
-                });
-                (new, true)
+                );
+                (new.expr(), true)
             }
         }
     }

src/main.rs

@@ -80,7 +80,7 @@ fn main() -> anyhow::Result<()> {
                 .parse(stream)
                 .map_err(|e| anyhow!("{e:?}"))?;
 
-            println!("{}", pretty::pretty_to_string(program, 100));
+            print!("{}", pretty::pretty_to_string(program, 100));
         }
 
         Command::Desugar {

src/parser/basic.rs

@@ -3,7 +3,7 @@
 use chumsky::prelude::*;
 use chumsky::text::Character;
 
-use crate::ast::{Ident, Line, Separated, Space};
+use crate::ast::{BoundedSeparated, Ident, Line, Space};
 use crate::span::Span;
 
 pub type Error = Simple<char, Span>;
@@ -62,23 +62,42 @@ pub fn local(space: EParser<Space>) -> EParser<Option<Space>> {
 // This function is more of a utility function. Because of this and to keep the
 // code nicer, I have decided that the rules specified in the `parser` module
 // don't apply to it.
-pub fn separated_by<E: 'static, S1: 'static, S2: 'static>(
+pub fn bounded_separated<E: 'static>(
+    space: impl Parser<char, Space, Error = Error> + Clone + 'static,
+    start: impl Parser<char, (), Error = Error> + 'static,
+    end: impl Parser<char, (), Error = Error> + 'static,
+    separator: impl Parser<char, (), Error = Error> + 'static,
     elem: impl Parser<char, E, Error = Error> + Clone + 'static,
-    separator: impl Parser<char, S1, Error = Error> + 'static,
-    trailing_separator: impl Parser<char, S2, Error = Error> + 'static,
-) -> EParser<Separated<E, S1, S2>> {
-    elem.clone()
-        .then(separator.then(elem).repeated())
-        .then(trailing_separator.or_not())
-        .or_not()
-        .map_with_span(|s, span| match s {
-            Some(((first_elem, last_elems), trailing)) => Separated::NonEmpty {
-                first_elem,
-                last_elems,
+) -> EParser<BoundedSeparated<E>> {
+    start
+        .ignore_then(space.clone())
+        .then(
+            elem.clone()
+                .then(space.clone())
+                .then_ignore(separator)
+                .then(space.clone())
+                .repeated(),
+        )
+        .then(elem.then(space).or_not())
+        .then_ignore(end)
+        .map_with_span(|((s0, first_elems), last_elem), span| {
+            let mut space_before_elem = s0;
+            let mut elems = vec![];
+            for ((elem, s1), s2) in first_elems {
+                elems.push((space_before_elem, elem, s1));
+                space_before_elem = s2;
+            }
+            let trailing = if let Some((elem, s1)) = last_elem {
+                elems.push((space_before_elem, elem, s1));
+                None
+            } else {
+                Some(space_before_elem)
+            };
+            BoundedSeparated {
+                elems,
                 trailing,
                 span,
-            },
-            None => Separated::Empty(span),
+            }
         })
         .boxed()
 }

src/parser/expr.rs

@@ -18,7 +18,7 @@ fn atom_paren(
         .then_ignore(just(')'))
         .map_with_span(|((s0, inner), s1), span| Expr::Paren {
             s0,
-            inner: Box::new(inner),
+            inner: inner.boxed(),
             s1,
             span,
         })
@@ -63,11 +63,11 @@ fn left_assoc(
     over.then(op_over.repeated())
         .foldl(|left, (s0, op, s1, right)| Expr::BinOp {
             span: left.span().join(right.span()),
-            left: Box::new(left),
+            left: left.boxed(),
             s0,
             op,
             s1,
-            right: Box::new(right),
+            right: right.boxed(),
         })
         .boxed()
 }
@@ -89,11 +89,11 @@ fn right_assoc(
         .then(over)
         .foldr(|(left, s0, op, s1), right| Expr::BinOp {
             span: left.span().join(right.span()),
-            left: Box::new(left),
+            left: left.boxed(),
             s0,
             op,
             s1,
-            right: Box::new(right),
+            right: right.boxed(),
         })
         .boxed()
 }

src/parser/func_def.rs

@@ -19,7 +19,7 @@ fn func_def_anon_no_arg(
             s0,
             s1,
             s2,
-            body: Box::new(body),
+            body: body.boxed(),
             span,
         })
 }
@@ -45,7 +45,7 @@ fn func_def_anon_arg(
                 arg,
                 s2,
                 s3,
-                body: Box::new(body),
+                body: body.boxed(),
                 span,
             },
         )
@@ -65,7 +65,7 @@ fn func_def_anon_destr(
             s0,
             pattern,
             s1,
-            body: Box::new(body),
+            body: body.boxed(),
             span,
         })
 }
@@ -94,7 +94,7 @@ fn func_def_named_no_arg(
                 s1,
                 s2,
                 s3,
-                body: Box::new(body),
+                body: body.boxed(),
                 span,
             },
         )
@@ -128,7 +128,7 @@ fn func_def_named_arg(
                 arg,
                 s3,
                 s4,
-                body: Box::new(body),
+                body: body.boxed(),
                 span,
             },
         )
@@ -157,7 +157,7 @@ fn func_def_named_destr(
                 s1,
                 pattern,
                 s2,
-                body: Box::new(body),
+                body: body.boxed(),
                 span,
             }
         })

src/parser/lit.rs

@@ -7,7 +7,7 @@ use crate::ast::{
 };
 use crate::builtin::Builtin;
 
-use super::basic::{separated_by, EParser, Error};
+use super::basic::{bounded_separated, EParser, Error};
 
 fn builtin_lit() -> impl Parser<char, Builtin, Error = Error> {
     just('\'').ignore_then(choice((
@@ -132,7 +132,7 @@ pub fn table_lit_elem(
 ) -> EParser<TableLitElem> {
     let positional = expr
         .clone()
-        .map(|value| TableLitElem::Positional(Box::new(value)));
+        .map(|value| TableLitElem::Positional(value.boxed()));
 
     let named = ident
         .then(space.clone())
@@ -143,7 +143,7 @@ pub fn table_lit_elem(
             name,
             s0,
             s1,
-            value: Box::new(value),
+            value: value.boxed(),
             span,
         });
 
@@ -154,20 +154,14 @@ fn table_lit(
     space: EParser<Space>,
     table_lit_elem: EParser<TableLitElem>,
 ) -> impl Parser<char, TableLit, Error = Error> {
-    let separator = space.clone().then_ignore(just(',')).then(space.clone());
-    let trailing_separator = space.clone().then_ignore(just(','));
-
-    space
-        .clone()
-        .then(separated_by(table_lit_elem, separator, trailing_separator))
-        .then(space)
-        .delimited_by(just("'{"), just('}'))
-        .map_with_span(|((s0, elems), s1), span| TableLit {
-            s0,
-            elems,
-            s1,
-            span,
-        })
+    bounded_separated(
+        space,
+        just("'{").to(()),
+        just('}').to(()),
+        just(',').to(()),
+        table_lit_elem,
+    )
+    .map(TableLit)
 }
 
 pub fn lit(space: EParser<Space>, table_lit_elem: EParser<TableLitElem>) -> EParser<Lit> {

src/parser/prefix.rs

@@ -17,7 +17,7 @@ enum Prefix {
 
 impl Prefix {
     fn into_expr(self, span: Span, expr: Expr) -> Expr {
-        let expr = Box::new(expr);
+        let expr = expr.boxed();
         match self {
             Self::Neg { minus, s0 } => Expr::Neg {
                 minus,

src/parser/program.rs

@@ -4,7 +4,7 @@ use chumsky::prelude::*;
 
 use crate::ast::{Expr, Program, Space, TableLitElem};
 
-use super::basic::{separated_by, EParser};
+use super::basic::{bounded_separated, EParser};
 
 pub fn program(
     space: EParser<Space>,
@@ -17,21 +17,17 @@ pub fn program(
         .then(space.clone())
         .map_with_span(|((s0, expr), s1), span| Program::Expr { s0, expr, s1, span });
 
-    let separator = space.clone().then_ignore(just(',')).then(space.clone());
-    let trailing_separator = space.clone().then_ignore(just(','));
     let module = space
         .clone()
         .then_ignore(text::keyword("module"))
-        .then(space.clone())
-        .then(separated_by(table_lit_elem, separator, trailing_separator))
-        .then(space.clone())
-        .map_with_span(|(((s0, s1), elems), s2), span| Program::Module {
-            s0,
-            s1,
-            elems,
-            s2,
-            span,
-        });
+        .then(bounded_separated(
+            space,
+            empty(),
+            empty(),
+            just(',').to(()),
+            table_lit_elem,
+        ))
+        .map_with_span(|(s0, elems), span| Program::Module { s0, elems, span });
 
     module.or(lit).boxed()
 }

src/parser/suffix.rs

@@ -57,31 +57,38 @@ enum Suffix {
 
 impl Suffix {
     fn into_expr(self, span: Span, expr: Expr) -> Expr {
-        let expr = Box::new(expr);
+        let expr = expr.boxed();
         match self {
-            Self::CallArg { s0, s1, arg, s2 } => Expr::Call(Call::Arg {
+            Self::CallArg { s0, s1, arg, s2 } => Call::Arg {
                 expr,
                 s0,
                 s1,
                 arg,
                 s2,
                 span,
-            }),
-            Self::CallNoArg { s0, s1 } => Expr::Call(Call::NoArg { expr, s0, s1, span }),
-            Self::CallConstr { s0, constr } => Expr::Call(Call::Constr {
+            }
+            .expr(),
+
+            Self::CallNoArg { s0, s1 } => Call::NoArg { expr, s0, s1, span }.expr(),
+
+            Self::CallConstr { s0, constr } => Call::Constr {
                 expr,
                 s0,
                 constr,
                 span,
-            }),
-            Self::FieldAccess { s0, s1, index, s2 } => Expr::Field(Field::Access {
+            }
+            .expr(),
+
+            Self::FieldAccess { s0, s1, index, s2 } => Field::Access {
                 expr,
                 s0,
                 s1,
                 index,
                 s2,
                 span,
-            }),
+            }
+            .expr(),
+
             Self::FieldAssign {
                 s0,
                 s1,
@@ -90,7 +97,7 @@ impl Suffix {
                 s3,
                 s4,
                 value,
-            } => Expr::Field(Field::Assign {
+            } => Field::Assign {
                 expr,
                 s0,
                 s1,
@@ -100,14 +107,18 @@ impl Suffix {
                 s4,
                 value,
                 span,
-            }),
-            Self::FieldAccessIdent { s0, s1, ident } => Expr::Field(Field::AccessIdent {
+            }
+            .expr(),
+
+            Self::FieldAccessIdent { s0, s1, ident } => Field::AccessIdent {
                 expr,
                 s0,
                 s1,
                 ident,
                 span,
-            }),
+            }
+            .expr(),
+
             Self::FieldAssignIdent {
                 s0,
                 s1,
@@ -115,7 +126,7 @@ impl Suffix {
                 s2,
                 s3,
                 value,
-            } => Expr::Field(Field::AssignIdent {
+            } => Field::AssignIdent {
                 expr,
                 s0,
                 s1,
@@ -124,7 +135,8 @@ impl Suffix {
                 s3,
                 value,
                 span,
-            }),
+            }
+            .expr(),
         }
     }
 }
@@ -143,7 +155,7 @@ fn suffix_call_arg(
         .map(|(((s0, s1), arg), s2)| Suffix::CallArg {
             s0,
             s1,
-            arg: Box::new(arg),
+            arg: arg.boxed(),
             s2,
         })
 }
@@ -180,7 +192,7 @@ fn suffix_field_access(
         .map(|(((s0, s1), index), s2)| Suffix::FieldAccess {
             s0,
             s1,
-            index: Box::new(index),
+            index: index.boxed(),
             s2,
         })
 }
@@ -204,11 +216,11 @@ fn suffix_field_assign(
             |((((((s0, s1), index), s2), s3), s4), value)| Suffix::FieldAssign {
                 s0,
                 s1,
-                index: Box::new(index),
+                index: index.boxed(),
                 s2,
                 s3,
                 s4,
-                value: Box::new(value),
+                value: value.boxed(),
             },
         )
 }
@@ -246,7 +258,7 @@ fn suffix_field_assign_ident(
                 ident,
                 s2,
                 s3,
-                value: Box::new(value),
+                value: value.boxed(),
             },
         )
 }

src/parser/table_constr.rs

@@ -4,7 +4,7 @@ use chumsky::prelude::*;
 
 use crate::ast::{Expr, Space, TableConstr, TableConstrElem, TableLitElem};
 
-use super::basic::{separated_by, EParser, Error};
+use super::basic::{bounded_separated, EParser, Error};
 
 fn table_constr_elem(
     space: EParser<Space>,
@@ -25,11 +25,11 @@ fn table_constr_elem(
         .map_with_span(
             |(((((s0, index), s1), s2), s3), value), span| TableConstrElem::Indexed {
                 s0,
-                index: Box::new(index),
+                index: index.boxed(),
                 s1,
                 s2,
                 s3,
-                value: Box::new(value),
+                value: value.boxed(),
                 span,
             },
         );
@@ -43,19 +43,13 @@ pub fn table_constr(
     expr: EParser<Expr>,
 ) -> EParser<TableConstr> {
     let elem = table_constr_elem(space.clone(), table_lit_elem, expr);
-    let separator = space.clone().then_ignore(just(',')).then(space.clone());
-    let trailing_separator = space.clone().then_ignore(just(','));
-
-    space
-        .clone()
-        .then(separated_by(elem, separator, trailing_separator))
-        .then(space)
-        .delimited_by(just('{'), just('}'))
-        .map_with_span(|((s0, elems), s1), span| TableConstr {
-            s0,
-            elems,
-            s1,
-            span,
-        })
-        .boxed()
+    bounded_separated(
+        space,
+        just('{').to(()),
+        just('}').to(()),
+        just(',').to(()),
+        elem,
+    )
+    .map(TableConstr)
+    .boxed()
 }

src/parser/table_destr.rs

@@ -4,7 +4,7 @@ use chumsky::prelude::*;
 
 use crate::ast::{Expr, Ident, Space, TableDestr, TablePattern, TablePatternElem};
 
-use super::basic::{separated_by, EParser, Error};
+use super::basic::{bounded_separated, EParser, Error};
 
 fn table_pattern_elem(
     space: EParser<Space>,
@@ -31,21 +31,15 @@ fn table_pattern_elem(
 
 pub fn table_pattern(space: EParser<Space>, ident: EParser<Ident>) -> EParser<TablePattern> {
     let elem = table_pattern_elem(space.clone(), ident);
-    let separator = space.clone().then_ignore(just(',')).then(space.clone());
-    let trailing_separator = space.clone().then_ignore(just(','));
-
-    space
-        .clone()
-        .then(separated_by(elem, separator, trailing_separator))
-        .then(space)
-        .delimited_by(just('{'), just('}'))
-        .map_with_span(|((s0, elems), s1), span| TablePattern {
-            s0,
-            elems,
-            s1,
-            span,
-        })
-        .boxed()
+    bounded_separated(
+        space,
+        just('{').to(()),
+        just('}').to(()),
+        just(',').to(()),
+        elem,
+    )
+    .map(TablePattern)
+    .boxed()
 }
 
 pub fn table_destr(
@@ -65,7 +59,7 @@ pub fn table_destr(
             pattern,
             s0,
             s1,
-            value: Box::new(value),
+            value: value.boxed(),
             span,
         })
         .boxed()

src/parser/var.rs

@@ -14,7 +14,7 @@ fn var_access(space: EParser<Space>, expr: EParser<Expr>) -> impl Parser<char, V
         .then_ignore(just(']'))
         .map_with_span(|((s0, index), s1), span| Var::Access {
             s0,
-            index: Box::new(index),
+            index: index.boxed(),
             s1,
             span,
         })
@@ -39,11 +39,11 @@ fn var_assign(
             |((((((local, s0), index), s1), s2), s3), value), span| Var::Assign {
                 local,
                 s0,
-                index: Box::new(index),
+                index: index.boxed(),
                 s1,
                 s2,
                 s3,
-                value: Box::new(value),
+                value: value.boxed(),
                 span,
             },
         )
@@ -67,7 +67,7 @@ fn var_assign_ident(
                 name,
                 s0,
                 s1,
-                value: Box::new(value),
+                value: value.boxed(),
                 span,
             },
         )

src/pretty.rs

@@ -1,3 +1,6 @@
+// TODO Remove this and print whitespace and comments properly
+#![allow(unused_variables)]
+
 use pretty::{Pretty, RcAllocator};
 
 mod basic;
@@ -18,5 +21,7 @@ pub fn pretty_to_string<P: Pretty<'static, RcAllocator>>(p: P, width: usize) ->
     p.pretty(&RcAllocator)
         .render(width, &mut out)
         .expect("p could not be rendered");
-    String::from_utf8(out).expect("p created non-utf8 string")
+    let mut s = String::from_utf8(out).expect("p created non-utf8 string");
+    s.push('\n');
+    s
 }

src/pretty/basic.rs

@@ -1,6 +1,8 @@
 use pretty::{DocAllocator, DocBuilder, Pretty};
 
-use crate::ast::{Ident, Separated};
+use crate::ast::{BoundedSeparated, Ident};
+
+use super::NEST_DEPTH;
 
 impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Ident {
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
@@ -8,40 +10,32 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Ident {
     }
 }
 
-impl<E, S1, S2> Separated<E, S1, S2> {
-    pub fn pretty<'a, D, FE, FS1, FS2>(
+impl<E> BoundedSeparated<E> {
+    pub fn pretty<'a, D, FE>(
         self,
         allocator: &'a D,
-        elem_to_doc: FE,
-        separator_to_doc: FS1,
-        trailing_separator_to_doc: FS2,
+        start: DocBuilder<'a, D>,
+        end: DocBuilder<'a, D>,
+        separator: DocBuilder<'a, D>,
+        elem_pretty: FE,
     ) -> DocBuilder<'a, D>
     where
         D: DocAllocator<'a>,
+        D::Doc: Clone,
         FE: Fn(E) -> DocBuilder<'a, D>,
-        FS1: Fn(S1) -> DocBuilder<'a, D>,
-        FS2: Fn(S2) -> DocBuilder<'a, D>,
     {
-        match self {
-            Self::Empty(_) => allocator.nil(),
-            Self::NonEmpty {
-                first_elem,
-                last_elems,
-                trailing,
-                span: _span,
-            } => elem_to_doc(first_elem)
-                .append(
-                    allocator.concat(
-                        last_elems
-                            .into_iter()
-                            .map(|(s, e)| separator_to_doc(s).append(elem_to_doc(e))),
-                    ),
-                )
-                .append(
-                    trailing
-                        .map(trailing_separator_to_doc)
-                        .unwrap_or_else(|| allocator.nil()),
-                ),
-        }
+        let elems_empty = self.elems.is_empty();
+        allocator
+            .intersperse(
+                self.elems
+                    .into_iter()
+                    .map(|(s0, elem, s1)| allocator.line().append(elem_pretty(elem))),
+                separator.clone(),
+            )
+            .append(self.trailing.filter(|_| !elems_empty).map(|s| separator))
+            .nest(NEST_DEPTH)
+            .append(allocator.line())
+            .enclose(start, end)
+            .group()
     }
 }

src/pretty/call.rs

@@ -2,7 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::Call;
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Call {
+impl<'a, D> Pretty<'a, D> for Call
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Arg {

src/pretty/expr.rs

@@ -22,7 +22,11 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for BinOp {
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Expr {
+impl<'a, D> Pretty<'a, D> for Expr
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Lit(lit) => lit.pretty(allocator),

src/pretty/field.rs

@@ -2,7 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::Field;
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Field {
+impl<'a, D> Pretty<'a, D> for Field
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Access {

src/pretty/func_def.rs

@@ -2,7 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::FuncDef;
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for FuncDef {
+impl<'a, D> Pretty<'a, D> for FuncDef
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::AnonNoArg {

src/pretty/lit.rs

@@ -2,8 +2,6 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::{Lit, NumLit, StringLit, StringLitElem, TableLit, TableLitElem};
 
-use super::NEST_DEPTH;
-
 impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for NumLit {
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         allocator.text(format!("{self:?}"))
@@ -32,7 +30,11 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for StringLit {
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableLitElem {
+impl<'a, D> Pretty<'a, D> for TableLitElem
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Positional(expr) => expr.pretty(allocator),
@@ -50,23 +52,27 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableLitElem {
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableLit {
+impl<'a, D> Pretty<'a, D> for TableLit
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
-        self.elems
-            .pretty(
-                allocator,
-                |e| allocator.line().append(e.pretty(allocator)),
-                |(s0, s1)| allocator.text(","),
-                |s| allocator.text(","),
-            )
-            .nest(NEST_DEPTH)
-            .append(allocator.line())
-            .enclose(allocator.text("'{"), allocator.text("}"))
-            .group()
+        self.0.pretty(
+            allocator,
+            allocator.text("'{"),
+            allocator.text("}"),
+            allocator.text(","),
+            |e| e.pretty(allocator),
+        )
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Lit {
+impl<'a, D> Pretty<'a, D> for Lit
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Nil(_) => allocator.text("nil"),

src/pretty/program.rs

@@ -2,7 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::Program;
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Program {
+impl<'a, D> Pretty<'a, D> for Program
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Expr {
@@ -11,22 +15,19 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Program {
                 s1,
                 span: _,
             } => expr.pretty(allocator),
-            Self::Module {
-                s0,
-                s1,
-                elems,
-                s2,
-                span: _,
-            } => allocator
-                .text("module")
-                .append(allocator.line())
-                .append(allocator.line())
-                .append(elems.pretty(
-                    allocator,
-                    |e| e.pretty(allocator),
-                    |(s0, s1)| allocator.text(",").append(allocator.line()),
-                    |s| allocator.text(","),
-                )),
+
+            Self::Module { s0, elems, span: _ } => {
+                allocator.text("module").append(allocator.line()).append(
+                    allocator
+                        .intersperse(
+                            elems.elems.into_iter().map(|(s0, elem, s1)| {
+                                allocator.line().append(elem.pretty(allocator))
+                            }),
+                            allocator.text(","),
+                        )
+                        .append(elems.trailing.map(|s| allocator.text(","))),
+                )
+            }
         }
     }
 }

src/pretty/table_constr.rs

@@ -2,9 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::{TableConstr, TableConstrElem};
 
-use super::NEST_DEPTH;
-
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableConstrElem {
+impl<'a, D> Pretty<'a, D> for TableConstrElem
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Lit(lit) => lit.pretty(allocator),
@@ -25,18 +27,18 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableConstrElem {
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableConstr {
+impl<'a, D> Pretty<'a, D> for TableConstr
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
-        self.elems
-            .pretty(
-                allocator,
-                |e| allocator.line().append(e.pretty(allocator)),
-                |(s0, s1)| allocator.text(","),
-                |s| allocator.text(","),
-            )
-            .nest(NEST_DEPTH)
-            .append(allocator.line())
-            .braces()
-            .group()
+        self.0.pretty(
+            allocator,
+            allocator.text("{"),
+            allocator.text("}"),
+            allocator.text(","),
+            |e| e.pretty(allocator),
+        )
     }
 }

src/pretty/table_destr.rs

@@ -2,8 +2,6 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::{TableDestr, TablePattern, TablePatternElem};
 
-use super::NEST_DEPTH;
-
 impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TablePatternElem {
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
@@ -22,23 +20,27 @@ impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TablePatternElem {
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TablePattern {
+impl<'a, D> Pretty<'a, D> for TablePattern
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
-        self.elems
-            .pretty(
-                allocator,
-                |e| allocator.line().append(e.pretty(allocator)),
-                |(s0, s1)| allocator.text(","),
-                |s| allocator.text(","),
-            )
-            .nest(NEST_DEPTH)
-            .append(allocator.line())
-            .braces()
-            .group()
+        self.0.pretty(
+            allocator,
+            allocator.text("{"),
+            allocator.text("}"),
+            allocator.text(","),
+            |e| e.pretty(allocator),
+        )
     }
 }
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for TableDestr {
+impl<'a, D> Pretty<'a, D> for TableDestr
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         // TODO Handle spaces
         self.local

src/pretty/var.rs

@@ -2,7 +2,11 @@ use pretty::{DocAllocator, DocBuilder, Pretty};
 
 use crate::ast::Var;
 
-impl<'a, D: DocAllocator<'a>> Pretty<'a, D> for Var {
+impl<'a, D> Pretty<'a, D> for Var
+where
+    D: DocAllocator<'a>,
+    D::Doc: Clone,
+{
     fn pretty(self, allocator: &'a D) -> DocBuilder<'a, D> {
         match self {
             Self::Access {