src/lambda_lift.rs

@@ -0,0 +1,8 @@
+use crate::syntax::{Expression, Name};
+use std::collections::{HashSet, HashMap};
+
+impl Expression {
+    fn free_variables(&self) -> HashSet<Name> {
+        unimplemented!()
+    }
+}

src/lib.rs

@@ -66,6 +66,7 @@ pub mod eval;
 #[cfg(test)]
 mod examples;
 pub mod ir;
+pub mod lambda_lift;
 pub mod syntax;
 pub mod type_infer;
 pub mod util;

src/repl.rs

@@ -134,8 +134,8 @@ impl REPL {
                 // if this is a variable binding, and we've never defined this variable before,
                 // we should tell cranelift about it. this is optimistic; if we fail to compile,
                 // then we won't use this definition until someone tries again.
-                if !self.variable_binding_sites.contains_key(&name.name) {
-                    self.jitter.define_string(&name.name)?;
+                if !self.variable_binding_sites.contains_key(&name.current_name().to_string()) {
+                    self.jitter.define_string(name.current_name())?;
                     self.jitter
                         .define_variable(name.to_string(), ConstantType::U64)?;
                 }
@@ -149,7 +149,7 @@ impl REPL {
                                 loc.clone(),
                                 crate::syntax::Name::manufactured("print"),
                             )),
-                            vec![Expression::Reference(loc.clone(), name.name)],
+                            vec![Expression::Reference(name.clone())],
                         )),
                     ],
                 }

src/syntax.rs

@@ -31,6 +31,7 @@ pub mod arbitrary;
 mod ast;
 pub mod eval;
 mod location;
+mod name;
 mod tokens;
 lalrpop_mod!(
     #[allow(clippy::just_underscores_and_digits, clippy::clone_on_copy)]
@@ -44,6 +45,7 @@ mod validate;
 use crate::syntax::arbitrary::GenerationEnvironment;
 pub use crate::syntax::ast::*;
 pub use crate::syntax::location::Location;
+pub use crate::syntax::name::Name;
 pub use crate::syntax::parser::{ProgramParser, TopLevelParser};
 pub use crate::syntax::tokens::{LexerError, Token};
 use lalrpop_util::ParseError;

src/syntax/arbitrary.rs

@@ -1,4 +1,5 @@
-use crate::syntax::ast::{ConstantType, Expression, Name, Program, TopLevel, Value};
+use crate::syntax::ast::{ConstantType, Expression, Program, TopLevel, Value};
+use crate::syntax::name::Name;
 use crate::syntax::location::Location;
 use proptest::sample::select;
 use proptest::{
@@ -88,10 +89,7 @@ impl Arbitrary for Program {
                                 Location::manufactured(),
                                 Name::manufactured("print"),
                             )),
-                            vec![Expression::Reference(
-                                Location::manufactured(),
-                                n.to_string(),
-                            )],
+                            vec![Expression::Reference(n.clone())],
                         )))
                     });
                     items.push(Union::new(printers).boxed());
@@ -168,12 +166,7 @@ impl Arbitrary for Expression {
         } else {
             let mut strats = bound_variables_of_type
                 .drain(..)
-                .map(|x| {
-                    Just(Expression::Reference(
-                        Location::manufactured(),
-                        x.name.clone(),
-                    ))
-                    .boxed()
+                .map(|x| { Just(Expression::Reference(x.clone())).boxed()
                 })
                 .collect::<Vec<_>>();
             strats.push(value_strategy);

src/syntax/ast.rs

@@ -1,10 +1,6 @@
-use std::fmt;
-use std::hash::Hash;
-
-use internment::ArcIntern;
-
-pub use crate::syntax::tokens::ConstantType;
+use crate::syntax::name::Name;
 use crate::syntax::Location;
+pub use crate::syntax::tokens::ConstantType;
 
 /// A structure represented a parsed program.
 ///
@@ -30,56 +26,6 @@ pub enum TopLevel {
     Structure(Location, Name, Vec<(Name, Type)>),
 }
 
-/// A Name.
-///
-/// This is basically a string, but annotated with the place the string
-/// is in the source file.
-#[derive(Clone, Debug)]
-pub struct Name {
-    pub name: String,
-    pub location: Location,
-}
-
-impl Name {
-    pub fn new<S: ToString>(n: S, location: Location) -> Name {
-        Name {
-            name: n.to_string(),
-            location,
-        }
-    }
-
-    pub fn manufactured<S: ToString>(n: S) -> Name {
-        Name {
-            name: n.to_string(),
-            location: Location::manufactured(),
-        }
-    }
-
-    pub fn intern(self) -> ArcIntern<String> {
-        ArcIntern::new(self.name)
-    }
-}
-
-impl PartialEq for Name {
-    fn eq(&self, other: &Self) -> bool {
-        self.name == other.name
-    }
-}
-
-impl Eq for Name {}
-
-impl Hash for Name {
-    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
-        self.name.hash(state)
-    }
-}
-
-impl fmt::Display for Name {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.name.fmt(f)
-    }
-}
-
 /// An expression in the underlying syntax.
 ///
 /// Like statements, these expressions are guaranteed to have been
@@ -90,7 +36,7 @@ impl fmt::Display for Name {
 pub enum Expression {
     Value(Location, Value),
     Constructor(Location, Name, Vec<(Name, Expression)>),
-    Reference(Location, String),
+    Reference(Name),
     FieldRef(Location, Box<Expression>, Name),
     Cast(Location, String, Box<Expression>),
     Primitive(Location, Name),
@@ -130,8 +76,8 @@ impl PartialEq for Expression {
                 Expression::Constructor(_, name2, fields2) => name1 == name2 && fields1 == fields2,
                 _ => false,
             },
-            Expression::Reference(_, var1) => match other {
-                Expression::Reference(_, var2) => var1 == var2,
+            Expression::Reference(var1) => match other {
+                Expression::Reference(var2) => var1 == var2,
                 _ => false,
             },
             Expression::FieldRef(_, exp1, field1) => match other {
@@ -174,7 +120,7 @@ impl Expression {
         match self {
             Expression::Value(loc, _) => loc,
             Expression::Constructor(loc, _, _) => loc,
-            Expression::Reference(loc, _) => loc,
+            Expression::Reference(n) => n.location(),
             Expression::FieldRef(loc, _, _) => loc,
             Expression::Cast(loc, _, _) => loc,
             Expression::Primitive(loc, _) => loc,

src/syntax/eval.rs

@@ -1,5 +1,5 @@
 use crate::eval::{EvalError, PrimitiveType, Value};
-use crate::syntax::{ConstantType, Expression, Name, Program, TopLevel};
+use crate::syntax::{ConstantType, Expression, Program, TopLevel};
 use crate::util::scoped_map::ScopedMap;
 use internment::ArcIntern;
 use std::collections::HashMap;
@@ -69,9 +69,9 @@ impl Expression {
                 Ok(Value::Structure(Some(on.clone().intern()), map))
             }
 
-            Expression::Reference(loc, n) => env
-                .get(&ArcIntern::new(n.clone()))
-                .ok_or_else(|| EvalError::LookupFailed(loc.clone(), n.clone()))
+            Expression::Reference(n) => env
+                .get(n.current_interned())
+                .ok_or_else(|| EvalError::LookupFailed(n.location().clone(), n.current_name().to_string()))
                 .cloned(),
 
             Expression::FieldRef(loc, expr, field) => {
@@ -102,7 +102,7 @@ impl Expression {
                 Ok(target_type.safe_cast(&value)?)
             }
 
-            Expression::Primitive(_, op) => Ok(Value::primitive(op.name.clone())),
+            Expression::Primitive(_, op) => Ok(Value::primitive(op.original_name().to_string())),
 
             Expression::Call(loc, fun, args) => {
                 let function = fun.eval(stdout, env)?;
@@ -129,8 +129,8 @@ impl Expression {
                     }
 
                     Value::Primitive(name) if name == "print" => {
-                        if let [Expression::Reference(_, name)] = &args[..] {
-                            let value = Expression::Reference(loc.clone(), name.clone())
+                        if let [Expression::Reference(name)] = &args[..] {
+                            let value = Expression::Reference(name.clone())
                                 .eval(stdout, env)?;
                             let value = match value {
                                 Value::Number(x) => Value::U64(x),
@@ -178,12 +178,12 @@ impl Expression {
 
             Expression::Function(_, name, arg_names, _, body) => {
                 let result = Value::Closure(
-                    name.clone().map(Name::intern),
+                    name.as_ref().map(|n| n.current_interned().clone()),
                     env.clone(),
                     arg_names
                         .iter()
                         .cloned()
-                        .map(|(x, _)| Name::intern(x))
+                        .map(|(x, _)| x.current_interned().clone())
                         .collect(),
                     *body.clone(),
                 );

src/syntax/name.rs

@@ -0,0 +1,113 @@
+use crate::syntax::Location;
+use internment::ArcIntern;
+use std::fmt;
+use std::hash::Hash;
+
+/// The name of a thing in the source language.
+///
+/// In many ways, you can treat this like a string, but it's a very tricky
+/// string in a couple of ways:
+/// 
+/// First, it's a string associated with a particular location in the source
+/// file, and you can find out what that source location is relatively easily.
+/// 
+/// Second, it's a name that retains something of its identity across renaming,
+/// so that you can keep track of what a variables original name was, as well as
+/// what it's new name is if it's been renamed.
+/// 
+/// Finally, when it comes to equality tests, comparisons, and hashing, `Name`
+/// uses *only* the new name, if the variable has been renamed, or the original
+/// name, if it has not been renamed. It never uses the location. This allows
+/// relatively fast hashing and searching for things like binding sites, as the
+/// value of the binding `Name` will be equal to the bound `Name`, even though
+/// they occur at different locations.
+#[derive(Clone, Debug)]
+pub struct Name {
+    name: ArcIntern<String>,
+    rename: Option<ArcIntern<String>>,
+    location: Location,
+}
+
+impl Name {
+    /// Create a new name at the given location.
+    /// 
+    /// This creates an "original" name, which has not been renamed, at the
+    /// given location.
+    pub fn new<S: ToString>(n: S, location: Location) -> Name {
+        Name {
+            name: ArcIntern::new(n.to_string()),
+            rename: None,
+            location,
+        }
+    }
+
+    /// Create a new name with no location information.
+    /// 
+    /// This creates an "original" name, which has not been renamed, at the
+    /// given location. You should always prefer to use [`Location::new`] if
+    /// there is any possible way to get it, because that will be more
+    /// helpful to our users.
+    pub fn manufactured<S: ToString>(n: S) -> Name {
+        Name {
+            name: ArcIntern::new(n.to_string()),
+            rename: None,
+            location: Location::manufactured(),
+        }
+    }
+
+    /// Returns a reference to the original name of the variable.
+    /// 
+    /// Regardless of whether or not the function has been renamed, this will
+    /// return whatever name this variable started with.
+    pub fn original_name(&self) -> &str {
+        self.name.as_str()
+    }
+
+    /// Returns a reference to the current name of the variable.
+    /// 
+    /// If the variable has been renamed, it will return that, otherwise we'll
+    /// return the current name.
+    pub fn current_name(&self) -> &str {
+        self.rename.as_ref().map(|x| x.as_str()).unwrap_or_else(|| self.name.as_str())
+    }
+
+    /// Returns the current name of the variable as an interned string.
+    pub fn current_interned(&self) -> &ArcIntern<String> {
+        self.rename.as_ref().unwrap_or(&self.name)
+    }
+
+    /// Return the location of this name.
+    pub fn location(&self) -> &Location {
+        &self.location
+    }
+
+    /// Rename this variable to the given value
+    pub fn rename(&mut self, new_name: &ArcIntern<String>) {
+        self.rename = Some(new_name.clone());
+    }
+
+    pub fn intern(&self) -> ArcIntern<String> {
+        self.current_interned().clone()
+    }
+}
+
+impl PartialEq for Name {
+    fn eq(&self, other: &Self) -> bool {
+        self.current_interned() == other.current_interned()
+    }
+}
+
+impl Eq for Name {}
+
+impl Hash for Name {
+    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
+        self.current_interned().hash(state)
+    }
+}
+
+impl fmt::Display for Name {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.current_name().fmt(f)
+    }
+}
+

src/syntax/parser.lalrpop

@@ -9,7 +9,8 @@
 //! eventually want to leave lalrpop behind.)
 //!
 use crate::syntax::{Location, ParserError};
-use crate::syntax::ast::{Program,TopLevel,Expression,Value,Name,Type};
+use crate::syntax::ast::{Program,TopLevel,Expression,Value,Type};
+use crate::syntax::name::Name;
 use crate::syntax::tokens::{ConstantType, Token};
 use internment::ArcIntern;
 
@@ -241,7 +242,7 @@ FieldExpression: Expression = {
 // they cannot be further divided into parts
 AtomicExpression: Expression = {
     // just a variable reference
-    <l: @L> <v:"<var>"> <end: @L> => Expression::Reference(Location::new(file_idx, l..end), v.to_string()),
+    <l: @L> <v:"<var>"> <end: @L> => Expression::Reference(Name::new(v.to_string(), Location::new(file_idx, l..end))),
     // just a number
     <l: @L> <n:"<num>"> <end: @L> => Expression::Value(Location::new(file_idx, l..end), Value::Number(n.0, n.1, n.2)),
     // this expression could actually be a block!

src/syntax/pretty.rs

@@ -67,7 +67,7 @@ impl Expression {
                         .nest(2)
                         .braces(),
                 ),
-            Expression::Reference(_, var) => allocator.text(var.to_string()),
+            Expression::Reference(var) => allocator.text(var.to_string()),
             Expression::FieldRef(_, val, field) => val
                 .pretty(allocator)
                 .append(allocator.text("."))
@@ -76,7 +76,7 @@ impl Expression {
                 .text(t.clone())
                 .angles()
                 .append(e.pretty(allocator)),
-            Expression::Primitive(_, op) => allocator.text(op.name.clone()),
+            Expression::Primitive(_, op) => allocator.text(op.original_name().to_string()),
             Expression::Call(_, fun, args) => {
                 let args = args.iter().map(|x| x.pretty(allocator));
                 let comma_sepped_args = allocator.intersperse(args, allocator.text(","));

src/syntax/validate.rs

@@ -141,9 +141,9 @@ impl Expression {
 
                 (errors, warnings)
             }
-            Expression::Reference(_, var) if variable_map.contains_key(var) => (vec![], vec![]),
-            Expression::Reference(loc, var) => (
-                vec![Error::UnboundVariable(loc.clone(), var.clone())],
+            Expression::Reference(var) if variable_map.contains_key(&var.original_name().to_string()) => (vec![], vec![]),
+            Expression::Reference(var) => (
+                vec![Error::UnboundVariable(var.location().clone(), var.original_name().to_string())],
                 vec![],
             ),
             Expression::FieldRef(_, exp, _) => exp.validate(variable_map),
@@ -187,7 +187,7 @@ impl Expression {
                 // immediately check the expression, and go from there.
                 let (errors, mut warnings) = val.validate(variable_map);
 
-                if let Some(original_binding_site) = variable_map.get(&var.name) {
+                if let Some(original_binding_site) = variable_map.get(&var.original_name().to_string()) {
                     warnings.push(Warning::ShadowedVariable(
                         original_binding_site.clone(),
                         loc.clone(),
@@ -201,11 +201,11 @@ impl Expression {
             }
             Expression::Function(_, name, arguments, _, body) => {
                 if let Some(name) = name {
-                    variable_map.insert(name.name.clone(), name.location.clone());
+                    variable_map.insert(name.original_name().to_string(), name.location().clone());
                 }
                 variable_map.new_scope();
                 for (arg, _) in arguments.iter() {
-                    variable_map.insert(arg.name.clone(), arg.location.clone());
+                    variable_map.insert(arg.original_name().to_string(), arg.location().clone());
                 }
                 let result = body.validate(variable_map);
                 variable_map.release_scope();

src/type_infer/convert.rs

@@ -191,20 +191,21 @@ impl InferenceEngine {
                 }
             }
 
-            syntax::Expression::Reference(loc, name) => {
-                let iname = ArcIntern::new(name);
-                let final_name = renames.get(&iname).cloned().unwrap_or(iname);
+            syntax::Expression::Reference(mut name) => {
+                if let Some(rename) = renames.get(name.current_interned()) {
+                    name.rename(rename);
+                }
                 let result_type = self
                     .variable_types
-                    .get(&final_name)
+                    .get(name.current_interned())
                     .cloned()
                     .expect("variable bound before use");
                 let expression = ir::Expression::Atomic(ir::ValueOrRef::Ref(
-                    loc,
+                    name.location().clone(),
                     result_type.clone(),
-                    final_name.clone(),
+                    name.current_interned().clone(),
                 ));
-                let free_variables = HashSet::from([final_name]);
+                let free_variables = HashSet::from([name.current_interned().clone()]);
 
                 ExpressionInfo {
                     expression,
@@ -260,7 +261,7 @@ impl InferenceEngine {
             }
 
             syntax::Expression::Primitive(loc, name) => {
-                let primop = ir::Primitive::from_str(&name.name).expect("valid primitive");
+                let primop = ir::Primitive::from_str(&name.current_name()).expect("valid primitive");
 
                 match primop {
                     ir::Primitive::Plus | ir::Primitive::Times | ir::Primitive::Divide => {
@@ -404,12 +405,12 @@ impl InferenceEngine {
                 expr_info
             }
 
-            syntax::Expression::Function(_, name, args, _, expr) => {
+            syntax::Expression::Function(loc, name, args, _, expr) => {
                 // First, at some point we're going to want to know a location for this function,
                 // which should either be the name if we have one, or the body if we don't.
                 let function_location = match name {
                     None => expr.location().clone(),
-                    Some(ref name) => name.location.clone(),
+                    Some(ref name) => loc,
                 };
                 // Next, let us figure out what we're going to name this function. If the user
                 // didn't provide one, we'll just call it "function:<something>" for them. (We'll
@@ -440,7 +441,7 @@ impl InferenceEngine {
                     .map(|(name, mut declared_type)| {
                         let new_type = ir::TypeOrVar::new();
                         self.constraints.push(Constraint::IsSomething(
-                            name.location.clone(),
+                            name.location().clone(),
                             new_type.clone(),
                         ));
                         let new_name = self.finalize_name(renames, name.clone());
@@ -450,7 +451,7 @@ impl InferenceEngine {
                         if let Some(declared_type) = declared_type.take() {
                             let declared_type = self.convert_type(declared_type);
                             self.constraints.push(Constraint::Equivalent(
-                                name.location.clone(),
+                                name.location().clone(),
                                 new_type.clone(),
                                 declared_type,
                             ));
@@ -495,11 +496,11 @@ impl InferenceEngine {
 
     fn convert_type(&mut self, ty: syntax::Type) -> ir::TypeOrVar {
         match ty {
-            syntax::Type::Named(x) => match PrimitiveType::from_str(x.name.as_str()) {
+            syntax::Type::Named(x) => match PrimitiveType::from_str(x.current_name()) {
                 Err(_) => {
-                    let retval = ir::TypeOrVar::new_located(x.location.clone());
+                    let retval = ir::TypeOrVar::new_located(x.location().clone());
                     self.constraints.push(Constraint::NamedTypeIs(
-                        x.location.clone(),
+                        x.location().clone(),
                         x.intern(),
                         retval.clone(),
                     ));
@@ -529,10 +530,10 @@ impl InferenceEngine {
     ) -> ArcIntern<String> {
         if self
             .variable_types
-            .contains_key(&ArcIntern::new(name.name.clone()))
+            .contains_key(name.current_interned())
         {
-            let new_name = ir::gensym(&name.name);
-            renames.insert(ArcIntern::new(name.name.to_string()), new_name.clone());
+            let new_name = ir::gensym(&name.original_name());
+            renames.insert(name.current_interned().clone(), new_name.clone());
             new_name
         } else {
             ArcIntern::new(name.to_string())