Broken structure now gets through syntax evaluator.

src/syntax/ast.rs

@@ -27,7 +27,13 @@ pub struct Program {
 #[derive(Clone, Debug, PartialEq)]
 pub enum TopLevel {
     Statement(Statement),
-    Function(Option<Name>, Vec<Name>, Expression),
+    Function(
+        Option<Name>,
+        Vec<(Name, Option<Type>)>,
+        Option<Type>,
+        Expression,
+    ),
+    Structure(Location, Option<Name>, Vec<(Name, Type)>),
 }
 
 /// A Name.
@@ -126,7 +132,9 @@ impl PartialEq for Statement {
 #[derive(Clone, Debug)]
 pub enum Expression {
     Value(Location, Value),
+    Constructor(Location, Name, Vec<(Name, Expression)>),
     Reference(Location, String),
+    FieldRef(Location, Box<Expression>, Name),
     Cast(Location, String, Box<Expression>),
     Primitive(Location, String, Vec<Expression>),
     Call(Location, Box<Expression>, Vec<Expression>),
@@ -140,10 +148,18 @@ impl PartialEq for Expression {
                 Expression::Value(_, val2) => val1 == val2,
                 _ => false,
             },
+            Expression::Constructor(_, name1, fields1) => match other {
+                Expression::Constructor(_, name2, fields2) => name1 == name2 && fields1 == fields2,
+                _ => false,
+            },
             Expression::Reference(_, var1) => match other {
                 Expression::Reference(_, var2) => var1 == var2,
                 _ => false,
             },
+            Expression::FieldRef(_, exp1, field1) => match other {
+                Expression::FieldRef(_, exp2, field2) => exp1 == exp2 && field1 == field2,
+                _ => false,
+            },
             Expression::Cast(_, t1, e1) => match other {
                 Expression::Cast(_, t2, e2) => t1 == t2 && e1 == e2,
                 _ => false,
@@ -169,7 +185,9 @@ impl Expression {
     pub fn location(&self) -> &Location {
         match self {
             Expression::Value(loc, _) => loc,
+            Expression::Constructor(loc, _, _) => loc,
             Expression::Reference(loc, _) => loc,
+            Expression::FieldRef(loc, _, _) => loc,
             Expression::Cast(loc, _, _) => loc,
             Expression::Primitive(loc, _, _) => loc,
             Expression::Call(loc, _, _) => loc,
@@ -190,3 +208,9 @@ pub enum Value {
     /// number at a later time.
     Number(Option<u8>, Option<ConstantType>, u64),
 }
+
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub enum Type {
+    Named(Name),
+    Struct(Option<Name>, Vec<(Option<Name>, Option<Type>)>),
+}

src/syntax/eval.rs

@@ -2,6 +2,7 @@ use crate::eval::{EvalError, PrimitiveType, Value};
 use crate::syntax::{ConstantType, Expression, Name, Program, Statement, TopLevel};
 use crate::util::scoped_map::ScopedMap;
 use internment::ArcIntern;
+use std::collections::HashMap;
 use std::str::FromStr;
 
 impl Program {
@@ -23,11 +24,15 @@ impl Program {
 
         for stmt in self.items.iter() {
             match stmt {
-                TopLevel::Function(name, arg_names, body) => {
+                TopLevel::Function(name, arg_names, _, body) => {
                     last_result = Value::Closure(
                         name.clone().map(Name::intern),
                         env.clone(),
-                        arg_names.iter().cloned().map(Name::intern).collect(),
+                        arg_names
+                            .iter()
+                            .cloned()
+                            .map(|(x, _)| Name::intern(x))
+                            .collect(),
                         body.clone(),
                     );
                     if let Some(name) = name {
@@ -36,6 +41,10 @@ impl Program {
                 }
 
                 TopLevel::Statement(stmt) => last_result = stmt.eval(&mut stdout, &mut env)?,
+
+                TopLevel::Structure(_, _, _) => {
+                    last_result = Value::Void;
+                }
             }
         }
 
@@ -98,11 +107,43 @@ impl Expression {
                 },
             },
 
+            Expression::Constructor(_, on, fields) => {
+                let mut map = HashMap::with_capacity(fields.len());
+
+                for (k, v) in fields.iter() {
+                    map.insert(k.clone().intern(), v.eval(stdout, env)?);
+                }
+
+                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()))
                 .cloned(),
 
+            Expression::FieldRef(loc, expr, field) => {
+                let struck = expr.eval(stdout, env)?;
+
+                if let Value::Structure(on, mut fields) = struck {
+                    if let Some(value) = fields.remove(&field.clone().intern()) {
+                        Ok(value)
+                    } else {
+                        Err(EvalError::BadFieldForStructure(
+                            loc.clone(),
+                            on,
+                            field.clone().intern(),
+                        ))
+                    }
+                } else {
+                    Err(EvalError::NoFieldForValue(
+                        loc.clone(),
+                        struck,
+                        field.clone().intern(),
+                    ))
+                }
+            }
+
             Expression::Cast(_, target, expr) => {
                 let target_type = PrimitiveType::from_str(target)?;
                 let value = expr.eval(stdout, env)?;

src/syntax/parser.lalrpop

@@ -9,7 +9,7 @@
 //! eventually want to leave lalrpop behind.)
 //!
 use crate::syntax::{Location, ParserError};
-use crate::syntax::ast::{Program,TopLevel,Statement,Expression,Value,Name};
+use crate::syntax::ast::{Program,TopLevel,Statement,Expression,Value,Name,Type};
 use crate::syntax::tokens::{ConstantType, Token};
 use internment::ArcIntern;
 
@@ -29,16 +29,21 @@ extern {
     // here we redeclare all of the tokens.
     enum Token {
         "=" => Token::Equals,
+        ":" => Token::Colon,
         ";" => Token::Semi,
         "," => Token::Comma,
+        "." => Token::Dot,
         "(" => Token::LeftParen,
         ")" => Token::RightParen,
         "<" => Token::LessThan,
         ">" => Token::GreaterThan,
+        "_" => Token::Underscore,
         "{" => Token::OpenBrace,
         "}" => Token::CloseBrace,
+        "->" => Token::SingleArrow,
 
         "function" => Token::Function,
+        "struct" => Token::Struct,
         "print" => Token::Print,
 
         "+" => Token::Operator('+'),
@@ -53,6 +58,7 @@ extern {
         // which is why we put their types in angle brackets.
         "<num>" => Token::Number((<Option<u8>>,<Option<ConstantType>>,<u64>)),
         "<var>" => Token::Variable(<ArcIntern<String>>),
+        "<type>" => Token::TypeName(<ArcIntern<String>>),
     }
 }
 
@@ -74,38 +80,18 @@ ProgramTopLevel: Vec<TopLevel> = {
 
 pub TopLevel: TopLevel = {
     <f:Function> => f,
+    <s:Structure> => s,
     <s:Statement> ";" => TopLevel::Statement(s),
 }
 
 Function: TopLevel = {
-    "function" <opt_name:OptionalName> "(" <args:Arguments> OptionalComma ")" <exp:Expression> ";" =>
-        TopLevel::Function(opt_name, args, exp),
-//    "function" <opt_name:OptionalName> "(" <args:Arguments> OptionalComma ")" <s:@L> "{" "}" <e:@L> =>
-//        TopLevel::Function(opt_name, args, Expression::Block(Location::new(file_idx, s..e), vec![])),
-//    "function" <opt_name:OptionalName> "(" <args:Arguments> OptionalComma ")" <s:@L> "{" <stmts:Statements> "}" <e:@L> =>
-//        TopLevel::Function(opt_name, args, Expression::Block(Location::new(file_idx, s..e), stmts)),
+    "function" <opt_name:Name?> "(" <args:Comma<Argument>> ")" <ret:("->" Type)?> <exp:Expression> ";" =>
+        TopLevel::Function(opt_name, args, ret.map(|x| x.1), exp),
 }
 
-OptionalName: Option<Name> = {
-    <name_start: @L> <v:"<var>"> <name_end: @L> =>
-        Some(Name::new(v, Location::new(file_idx, name_start..name_end))),
-    => None,
-}
-
-Arguments: Vec<Name> = {
-    <mut args:Arguments> "," <arg:Argument> => {
-        args.push(arg);
-        args
-    },
-
-    <arg:Argument> => vec![arg],
-
-    => Vec::new(),
-}
-
-Argument: Name = {
-    <name_start: @L> <v:"<var>"> <name_end: @L> => 
-        Name::new(v, Location::new(file_idx, name_start..name_end)),
+Argument: (Name, Option<Type>) = {
+    <name_start: @L> <v:"<var>"> <name_end: @L> <t:(":" Type)?> => 
+        (Name::new(v, Location::new(file_idx, name_start..name_end)), t.map(|v| v.1)),
 }
 
 OptionalComma: () = {
@@ -113,6 +99,40 @@ OptionalComma: () = {
     "," => (),
 }
 
+Structure: TopLevel = {
+    <s:@L> "struct" <on: TypeName?> "{" <fields: Field*> "}" <e:@L> => {
+        TopLevel::Structure(Location::new(file_idx, s..e), on, fields)
+    }
+}
+
+Field: (Name, Type) = {
+    <s:@L> <name:"<var>"> <e:@L> ":" <field_type: Type> ";" =>
+        (Name::new(name, Location::new(file_idx, s..e)), field_type)
+}
+
+Type: Type = {
+    <name:Name> => Type::Named(name),
+    <t:TypeName> => Type::Named(t),
+    "struct" <on: TypeName?> "{" <fields: TypeField*> "}" =>
+        Type::Struct(on, fields),
+}
+
+TypeField: (Option<Name>, Option<Type>) = {
+    <name: Name> ":" <ty: Type> ";" => (Some(name), Some(ty)),
+    <name: Name> (":" "_")? ";" => (Some(name), None),
+    "_" ":" <ty: Type> ";" => (None, Some(ty)),
+}
+
+Name: Name = {
+    <name_start: @L> <v:"<var>"> <name_end: @L> =>
+        Name::new(v, Location::new(file_idx, name_start..name_end)),
+}
+
+TypeName: Name = {
+    <name_start: @L> <v:"<type>"> <name_end: @L> =>
+        Name::new(v, Location::new(file_idx, name_start..name_end)),
+}
+
 Statements: Vec<Statement> = {
     // a statement is either a set of statements followed by another
     // statement (note, here, that you can name the result of a sub-parse
@@ -175,9 +195,19 @@ Statement: Statement = {
 // parse something like "1 + 2 * 3", for example, versus "1 + 2 + 3" or
 // "1 * 2 + 3", and hopefully that'll help.
 Expression: Expression = {
+    ConstructorExpression,
     AdditiveExpression,
 }
 
+ConstructorExpression: Expression = {
+    <s:@L> <name:TypeName> "{" <fields:FieldSetter*> "}" <e:@L> =>
+        Expression::Constructor(Location::new(file_idx, s..e), name, fields),
+}
+
+FieldSetter: (Name, Expression) = {
+    <name:Name> ":" <expr:Expression> ";" => (name, expr),
+}
+
 // we group addition and subtraction under the heading "additive"
 AdditiveExpression: Expression = {
     <ls: @L> <e1:AdditiveExpression> <l: @L> "+" <e2:MultiplicativeExpression> <le: @L> =>
@@ -205,18 +235,15 @@ UnaryExpression: Expression = {
 }
 
 CallExpression: Expression = {
-    <s: @L> <f:CallExpression> "(" <args: CallArguments> ")" <e: @L> =>
+    <s: @L> <f:CallExpression> "(" <args: Comma<Expression>> ")" <e: @L> =>
        Expression::Call(Location::new(file_idx, s..e), Box::new(f), args),
-    AtomicExpression,
+    FieldExpression,
 }
 
-CallArguments: Vec<Expression> = {
-    => vec![],
-    <e:Expression> => vec![e],
-    <mut args:CallArguments> "," <e:Expression> => {
-        args.push(e);
-        args
-    }
+FieldExpression: Expression = {
+    <s: @L> <fe:FieldExpression> "." <field:Name> <e: @L> =>
+        Expression::FieldRef(Location::new(file_idx, s..e), Box::new(fe), field),
+    AtomicExpression,
 }
 
 // finally, we describe our lowest-level expressions as "atomic", because
@@ -232,4 +259,16 @@ AtomicExpression: Expression = {
     // finally, let people parenthesize expressions and get back to a
     // lower precedence
     "(" <e:Expression> ")" => e,
-}
+}
+
+// Lifted from the LALRPop book, a comma-separated list of T that may or
+// may not conclude with a comma.
+Comma<T>: Vec<T> = {
+    <mut v:(<T> ",")*> <e:T?> => match e {
+        None => v,
+        Some(e) => {
+            v.push(e);
+            v
+        }
+    }
+};

src/syntax/pretty.rs

@@ -1,4 +1,4 @@
-use crate::syntax::ast::{ConstantType, Expression, Program, Statement, TopLevel, Value};
+use crate::syntax::ast::{ConstantType, Expression, Program, Statement, TopLevel, Type, Value};
 use crate::util::pretty::{derived_display, Allocator};
 use pretty::{DocAllocator, DocBuilder};
 
@@ -21,7 +21,7 @@ impl TopLevel {
     pub fn pretty<'a>(&self, allocator: &'a Allocator<'a>) -> DocBuilder<'a, Allocator<'a>> {
         match self {
             TopLevel::Statement(stmt) => stmt.pretty(allocator),
-            TopLevel::Function(name, arg_names, body) => allocator
+            TopLevel::Function(name, args, rettype, body) => allocator
                 .text("function")
                 .append(allocator.space())
                 .append(
@@ -32,13 +32,61 @@ impl TopLevel {
                 .append(
                     allocator
                         .intersperse(
-                            arg_names.iter().map(|x| allocator.text(x.to_string())),
+                            args.iter().map(|(x, t)| {
+                                allocator.text(x.to_string()).append(
+                                    t.as_ref()
+                                        .map(|t| {
+                                            allocator
+                                                .text(":")
+                                                .append(allocator.space())
+                                                .append(t.pretty(allocator))
+                                        })
+                                        .unwrap_or_else(|| allocator.nil()),
+                                )
+                            }),
                             allocator.text(","),
                         )
                         .parens(),
                 )
+                .append(
+                    rettype
+                        .as_ref()
+                        .map(|rettype| {
+                            allocator
+                                .space()
+                                .append(allocator.text("->"))
+                                .append(allocator.space())
+                                .append(rettype.pretty(allocator))
+                        })
+                        .unwrap_or_else(|| allocator.nil()),
+                )
                 .append(allocator.space())
                 .append(body.pretty(allocator)),
+            TopLevel::Structure(_, name, fields) => allocator
+                .text("struct")
+                .append(allocator.space())
+                .append(
+                    name.as_ref()
+                        .map(|x| allocator.text(x.to_string()))
+                        .unwrap_or_else(|| allocator.nil()),
+                )
+                .append(allocator.space())
+                .append(allocator.text("{"))
+                .append(allocator.hardline())
+                .append(
+                    allocator
+                        .concat(fields.iter().map(|(name, ty)| {
+                            allocator
+                                .text(name.to_string())
+                                .append(allocator.text(":"))
+                                .append(allocator.space())
+                                .append(ty.pretty(allocator))
+                                .append(allocator.text(";"))
+                                .append(allocator.hardline())
+                        }))
+                        .nest(2),
+                )
+                .append(allocator.text("}")),
         }
     }
 }
@@ -65,7 +113,28 @@ impl Expression {
     pub fn pretty<'a>(&self, allocator: &'a Allocator<'a>) -> DocBuilder<'a, Allocator<'a>> {
         match self {
             Expression::Value(_, val) => val.pretty(allocator),
+            Expression::Constructor(_, name, fields) => allocator
+                .text(name.to_string())
+                .append(allocator.space())
+                .append(
+                    allocator
+                        .concat(fields.iter().map(|(n, e)| {
+                            allocator
+                                .text(n.to_string())
+                                .append(allocator.text(":"))
+                                .append(allocator.space())
+                                .append(e.pretty(allocator))
+                                .append(allocator.text(";"))
+                                .append(allocator.hardline())
+                        }))
+                        .nest(2)
+                        .braces(),
+                ),
             Expression::Reference(_, var) => allocator.text(var.to_string()),
+            Expression::FieldRef(_, val, field) => val
+                .pretty(allocator)
+                .append(allocator.text("."))
+                .append(allocator.text(field.to_string())),
             Expression::Cast(_, t, e) => allocator
                 .text(t.clone())
                 .angles()
@@ -151,6 +220,42 @@ fn type_suffix(x: &Option<ConstantType>) -> &'static str {
     }
 }
 
+impl Type {
+    pub fn pretty<'a>(&self, allocator: &'a Allocator<'a>) -> DocBuilder<'a, Allocator<'a>> {
+        match self {
+            Type::Named(x) => allocator.text(x.to_string()),
+            Type::Struct(name, fields) => allocator
+                .text("struct")
+                .append(allocator.space())
+                .append(
+                    name.as_ref()
+                        .map(|x| allocator.text(x.to_string()))
+                        .unwrap_or_else(|| allocator.nil()),
+                )
+                .append(allocator.intersperse(
+                    fields.iter().map(|(name, ty)| {
+                        allocator
+                            .text(
+                                name.as_ref()
+                                    .map(|x| x.to_string())
+                                    .unwrap_or_else(|| "_".to_string()),
+                            )
+                            .append(allocator.text(":"))
+                            .append(allocator.space())
+                            .append(
+                                ty.as_ref()
+                                    .map(|x| x.pretty(allocator))
+                                    .unwrap_or_else(|| allocator.text("_")),
+                            )
+                            .append(allocator.text(";"))
+                    }),
+                    allocator.hardline(),
+                ))
+                .braces(),
+        }
+    }
+}
+
 derived_display!(Program);
 derived_display!(TopLevel);
 derived_display!(Statement);

src/syntax/tokens.rs

@@ -36,12 +36,18 @@ pub enum Token {
     #[token("=")]
     Equals,
 
+    #[token(":")]
+    Colon,
+
     #[token(";")]
     Semi,
 
     #[token(",")]
     Comma,
 
+    #[token(".")]
+    Dot,
+
     #[token("(")]
     LeftParen,
 
@@ -54,17 +60,26 @@ pub enum Token {
     #[token(">")]
     GreaterThan,
 
+    #[token("_")]
+    Underscore,
+
     #[token("{")]
     OpenBrace,
 
     #[token("}")]
     CloseBrace,
 
+    #[token("->")]
+    SingleArrow,
+
     #[token("λ")]
     #[token("lambda")]
     #[token("function")]
     Function,
 
+    #[token("struct")]
+    Struct,
+
     // Next we take of any reserved words; I always like to put
     // these before we start recognizing more complicated regular
     // expressions. I don't think it matters, but it works for me.
@@ -93,21 +108,31 @@ pub enum Token {
     // letter, too.
     #[regex(r"[a-z][a-zA-Z0-9_]*", |v| ArcIntern::new(v.slice().to_string()))]
     Variable(ArcIntern<String>),
+
+    // Type names; these are like variables, but must start with a capital
+    // letter.
+    #[regex(r"[A-Z][a-zA-Z0-9_]*", |v| ArcIntern::new(v.slice().to_string()))]
+    TypeName(ArcIntern<String>),
 }
 
 impl fmt::Display for Token {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             Token::Equals => write!(f, "'='"),
+            Token::Colon => write!(f, "':'"),
             Token::Semi => write!(f, "';'"),
             Token::Comma => write!(f, "','"),
+            Token::Dot => write!(f, "'.'"),
             Token::LeftParen => write!(f, "'('"),
             Token::RightParen => write!(f, "')'"),
             Token::LessThan => write!(f, "<"),
             Token::GreaterThan => write!(f, ">"),
+            Token::Underscore => write!(f, "_"),
             Token::OpenBrace => write!(f, "{{"),
             Token::CloseBrace => write!(f, "}}"),
+            Token::SingleArrow => write!(f, "->"),
             Token::Function => write!(f, "function"),
+            Token::Struct => write!(f, "struct"),
             Token::Print => write!(f, "'print'"),
             Token::Operator(c) => write!(f, "'{}'", c),
             Token::Number((None, otype, v)) => write!(f, "'{}{}'", v, display_optional_type(otype)),
@@ -131,6 +156,7 @@ impl fmt::Display for Token {
                 )
             }
             Token::Variable(s) => write!(f, "'{}'", s),
+            Token::TypeName(s) => write!(f, "'{}'", s),
         }
     }
 }

src/syntax/validate.rs

@@ -68,7 +68,7 @@ impl Program {
     /// actually a problem.
     pub fn validate(&self) -> (Vec<Error>, Vec<Warning>) {
         let mut bound_variables = ScopedMap::new();
-        println!("validate: {}", self);
+        println!("validate:\n{}", self);
         self.validate_with_bindings(&mut bound_variables)
     }
 
@@ -85,7 +85,7 @@ impl Program {
         let mut warnings = vec![];
 
         for stmt in self.items.iter() {
-            if let TopLevel::Function(Some(name), _, _) = stmt {
+            if let TopLevel::Function(Some(name), _, _, _) = stmt {
                 bound_variables.insert(name.to_string(), name.location.clone());
             }
             let (mut new_errors, mut new_warnings) = stmt.validate_with_bindings(bound_variables);
@@ -120,12 +120,12 @@ impl TopLevel {
         bound_variables: &mut ScopedMap<String, Location>,
     ) -> (Vec<Error>, Vec<Warning>) {
         match self {
-            TopLevel::Function(name, arguments, body) => {
+            TopLevel::Function(name, arguments, _, body) => {
                 bound_variables.new_scope();
                 if let Some(name) = name {
                     bound_variables.insert(name.name.clone(), name.location.clone());
                 }
-                for arg in arguments.iter() {
+                for (arg, _) in arguments.iter() {
                     bound_variables.insert(arg.name.clone(), arg.location.clone());
                 }
                 let result = body.validate(bound_variables);
@@ -133,6 +133,7 @@ impl TopLevel {
                 result
             }
             TopLevel::Statement(stmt) => stmt.validate(bound_variables),
+            TopLevel::Structure(_, _, _) => (vec![], vec![]),
         }
     }
 }
@@ -198,11 +199,24 @@ impl Expression {
     ) -> (Vec<Error>, Vec<Warning>) {
         match self {
             Expression::Value(_, _) => (vec![], vec![]),
+            Expression::Constructor(_, _, fields) => {
+                let mut errors = vec![];
+                let mut warnings = vec![];
+
+                for (_, expr) in fields.iter() {
+                    let (mut e, mut w) = expr.validate(variable_map);
+                    errors.append(&mut e);
+                    warnings.append(&mut w);
+                }
+
+                (errors, warnings)
+            }
             Expression::Reference(_, var) if variable_map.contains_key(var) => (vec![], vec![]),
             Expression::Reference(loc, var) => (
                 vec![Error::UnboundVariable(loc.clone(), var.clone())],
                 vec![],
             ),
+            Expression::FieldRef(_, exp, _) => exp.validate(variable_map),
             Expression::Cast(location, t, expr) => {
                 let (mut errs, warns) = expr.validate(variable_map);