Add doubles.

dm-std-lib/src/lib.rs

@@ -44,6 +44,9 @@ pub fn std_core_println(args: &[Value]) -> Result<Value, Box<dyn Error>> {
                 Value::Int(i) => {
                     println!("{}", i);
                 }
+                Value::Double(d) => {
+                    println!("{}", d);
+                }
                 Value::String(s) => {
                     println!("{}", s);
                 }

dmc-lib/src/ast/add_expression.rs

@@ -73,7 +73,7 @@ impl AddExpression {
             Ok(())
         } else {
             Err(vec![Diagnostic::new(
-                &format!("Cannot add {} to {}", lhs_type_info, rhs_type_info),
+                &format!("Cannot add {} to {}", rhs_type_info, lhs_type_info),
                 self.source_range.start(),
                 self.source_range.end(),
             )])

dmc-lib/src/ast/double_literal.rs

@@ -0,0 +1,31 @@
+use crate::source_range::SourceRange;
+use crate::type_info::TypeInfo;
+
+pub struct DoubleLiteral {
+    value: f64,
+    source_range: SourceRange,
+    type_info: &'static TypeInfo,
+}
+
+impl DoubleLiteral {
+    pub fn new(value: f64, source_range: SourceRange) -> Self {
+        const TYPE_INFO: TypeInfo = TypeInfo::Double;
+        Self {
+            value,
+            source_range,
+            type_info: &TYPE_INFO,
+        }
+    }
+
+    pub fn value(&self) -> f64 {
+        self.value
+    }
+
+    pub fn type_info(&self) -> &TypeInfo {
+        &self.type_info
+    }
+
+    pub fn source_range(&self) -> &SourceRange {
+        &self.source_range
+    }
+}

dmc-lib/src/ast/expression.rs

@@ -1,5 +1,6 @@
 use crate::ast::add_expression::AddExpression;
 use crate::ast::call::Call;
+use crate::ast::double_literal::DoubleLiteral;
 use crate::ast::identifier::Identifier;
 use crate::ast::integer_literal::IntegerLiteral;
 use crate::ast::ir_builder::IrBuilder;
@@ -25,6 +26,7 @@ pub enum Expression {
     Call(Call),
     Identifier(Identifier),
     Integer(IntegerLiteral),
+    Double(DoubleLiteral),
     String(StringLiteral),
 }
 
@@ -44,6 +46,7 @@ impl Expression {
             Expression::Call(call) => call.gather_declared_names(symbol_table),
             Expression::Identifier(identifier) => identifier.gather_declared_names(symbol_table),
             Expression::Integer(_) => Ok(()),
+            Expression::Double(_) => Ok(()),
             Expression::String(_) => Ok(()),
         }
     }
@@ -60,6 +63,7 @@ impl Expression {
             Expression::Call(call) => call.check_name_usages(symbol_table),
             Expression::Identifier(identifier) => identifier.check_name_usages(symbol_table),
             Expression::Integer(_) => Ok(()),
+            Expression::Double(_) => Ok(()),
             Expression::String(_) => Ok(()),
         }
     }
@@ -76,6 +80,7 @@ impl Expression {
             Expression::Call(call) => call.type_check(symbol_table),
             Expression::Identifier(identifier) => identifier.type_check(symbol_table),
             Expression::Integer(_) => Ok(()),
+            Expression::Double(_) => Ok(()),
             Expression::String(_) => Ok(()),
         }
     }
@@ -88,6 +93,7 @@ impl Expression {
             Expression::Call(call) => call.return_type_info(),
             Expression::Identifier(identifier) => identifier.type_info(),
             Expression::Integer(integer_literal) => integer_literal.type_info(),
+            Expression::Double(double_literal) => double_literal.type_info(),
             Expression::String(string_literal) => string_literal.type_info(),
         }
     }
@@ -100,6 +106,7 @@ impl Expression {
             Expression::Call(call) => call.source_range(),
             Expression::Identifier(identifier) => identifier.source_range(),
             Expression::Integer(integer_literal) => integer_literal.source_range(),
+            Expression::Double(double_literal) => double_literal.source_range(),
             Expression::String(string_literal) => string_literal.source_range(),
         }
     }
@@ -134,6 +141,9 @@ impl Expression {
             Expression::Integer(integer_literal) => {
                 Some(IrExpression::Int(integer_literal.value()))
             }
+            Expression::Double(double_literal) => {
+                Some(IrExpression::Double(double_literal.value()))
+            }
             Expression::String(string_literal) => {
                 Some(IrExpression::String(string_literal.content().into()))
             }

dmc-lib/src/ast/let_statement.rs

@@ -105,6 +105,9 @@ impl LetStatement {
             Expression::Integer(integer_literal) => {
                 IrOperation::Load(IrExpression::Int(integer_literal.value()))
             }
+            Expression::Double(double_literal) => {
+                IrOperation::Load(IrExpression::Double(double_literal.value()))
+            }
             Expression::String(string_literal) => {
                 IrOperation::Load(IrExpression::String(string_literal.content().into()))
             }

dmc-lib/src/ast/mod.rs

@@ -1,6 +1,7 @@
 pub mod add_expression;
 pub mod call;
 pub mod compilation_unit;
+pub mod double_literal;
 pub mod expression;
 pub mod expression_statement;
 pub mod extern_function;

dmc-lib/src/ir/ir_expression.rs

@@ -17,6 +17,7 @@ pub enum IrExpression {
     Parameter(Rc<IrParameter>),
     Variable(Rc<RefCell<IrVariable>>),
     Int(i32),
+    Double(f64),
     String(Rc<str>),
 }
 
@@ -26,6 +27,7 @@ impl IrExpression {
             IrExpression::Parameter(ir_parameter) => ir_parameter.type_info().clone(),
             IrExpression::Variable(ir_variable) => ir_variable.borrow().type_info().clone(),
             IrExpression::Int(_) => TypeInfo::Integer,
+            IrExpression::Double(_) => TypeInfo::Double,
             IrExpression::String(_) => TypeInfo::String,
         }
     }
@@ -44,6 +46,7 @@ impl IrExpression {
                 }
             },
             IrExpression::Int(i) => MoveOperand::Int(*i),
+            IrExpression::Double(d) => MoveOperand::Double(*d),
             IrExpression::String(s) => {
                 let constant_name = constants_table.get_or_insert(s);
                 MoveOperand::String(constant_name)
@@ -65,6 +68,7 @@ impl IrExpression {
                 }
             },
             IrExpression::Int(i) => PushOperand::Int(*i),
+            IrExpression::Double(d) => PushOperand::Double(*d),
             IrExpression::String(s) => {
                 let constant_name = constants_table.get_or_insert(s);
                 PushOperand::String(constant_name)
@@ -75,31 +79,34 @@ impl IrExpression {
     pub fn add_operand(&self, constants_table: &mut ConstantsTable) -> AddOperand {
         match self {
             IrExpression::Parameter(ir_parameter) => match ir_parameter.type_info() {
-                TypeInfo::Integer | TypeInfo::String => {
+                TypeInfo::Integer | TypeInfo::Double | TypeInfo::String => {
                     AddOperand::Location(Location::StackFrameOffset(ir_parameter.stack_offset()))
                 }
                 _ => panic!(
-                    "Attempt to add non-integer/non-string (found: {})",
+                    "Attempt to add non- integer/double/string (found: {})",
                     ir_parameter.type_info()
                 ),
             },
             IrExpression::Variable(ir_variable) => match ir_variable.borrow().type_info() {
-                TypeInfo::Integer | TypeInfo::String => match ir_variable.borrow().descriptor() {
+                TypeInfo::Integer | TypeInfo::Double | TypeInfo::String => {
-                    IrVariableDescriptor::VirtualRegister(register_variable) => {
+                    match ir_variable.borrow().descriptor() {
-                        AddOperand::Location(Location::Register(
+                        IrVariableDescriptor::VirtualRegister(register_variable) => {
-                            register_variable.assigned_register(),
+                            AddOperand::Location(Location::Register(
-                        ))
+                                register_variable.assigned_register(),
+                            ))
+                        }
+                        IrVariableDescriptor::Stack(stack_variable) => AddOperand::Location(
+                            Location::StackFrameOffset(stack_variable.offset()),
+                        ),
                     }
-                    IrVariableDescriptor::Stack(stack_variable) => {
+                }
-                        AddOperand::Location(Location::StackFrameOffset(stack_variable.offset()))
-                    }
-                },
                 _ => panic!(
                     "Attempt to add non-integer/non-string (found: {})",
                     ir_variable.borrow().type_info()
                 ),
             },
             IrExpression::Int(i) => AddOperand::Int(*i),
+            IrExpression::Double(d) => AddOperand::Double(*d),
             IrExpression::String(s) => {
                 let constant_name = constants_table.get_or_insert(s);
                 AddOperand::String(constant_name)
@@ -110,16 +117,16 @@ impl IrExpression {
     pub fn subtract_operand(&self) -> SubtractOperand {
         match self {
             IrExpression::Parameter(ir_parameter) => match ir_parameter.type_info() {
-                TypeInfo::Integer => SubtractOperand::Location(Location::StackFrameOffset(
+                TypeInfo::Integer | TypeInfo::Double => SubtractOperand::Location(
-                    ir_parameter.stack_offset(),
+                    Location::StackFrameOffset(ir_parameter.stack_offset()),
-                )),
+                ),
                 _ => panic!(
                     "Attempt to subtract with non-integer type (found {})",
                     ir_parameter.type_info()
                 ),
             },
             IrExpression::Variable(ir_variable) => match ir_variable.borrow().type_info() {
-                TypeInfo::Integer => match ir_variable.borrow().descriptor() {
+                TypeInfo::Integer | TypeInfo::Double => match ir_variable.borrow().descriptor() {
                     IrVariableDescriptor::VirtualRegister(vr_variable) => {
                         SubtractOperand::Location(Location::Register(
                             vr_variable.assigned_register(),
@@ -135,6 +142,7 @@ impl IrExpression {
                 ),
             },
             IrExpression::Int(i) => SubtractOperand::Int(*i),
+            IrExpression::Double(d) => SubtractOperand::Double(*d),
             IrExpression::String(_) => {
                 panic!("Attempt to subtract with a string");
             }
@@ -157,6 +165,7 @@ impl IrExpression {
                 }
             },
             IrExpression::Int(i) => ReturnOperand::Int(*i),
+            IrExpression::Double(d) => ReturnOperand::Double(*d),
             IrExpression::String(s) => {
                 let constant_name = constants_table.get_or_insert(s);
                 ReturnOperand::String(constant_name)
@@ -177,6 +186,9 @@ impl Display for IrExpression {
             IrExpression::Int(i) => {
                 write!(f, "{}", i)
             }
+            IrExpression::Double(d) => {
+                write!(f, "{}", d)
+            }
             IrExpression::String(s) => {
                 write!(f, "\"{}\"", s)
             }
@@ -202,6 +214,7 @@ impl VrUser for IrExpression {
                 }
             }
             IrExpression::Int(_) => HashSet::new(),
+            IrExpression::Double(_) => HashSet::new(),
             IrExpression::String(_) => HashSet::new(),
         }
     }
@@ -230,6 +243,9 @@ impl VrUser for IrExpression {
             IrExpression::Int(_) => {
                 // no-op
             }
+            IrExpression::Double(_) => {
+                // no-op
+            }
             IrExpression::String(_) => {
                 // no-op
             }
@@ -257,6 +273,9 @@ impl VrUser for IrExpression {
             IrExpression::Int(_) => {
                 // no-op
             }
+            IrExpression::Double(_) => {
+                // no-op
+            }
             IrExpression::String(_) => {
                 // no-op
             }

dmc-lib/src/lexer.rs

@@ -59,14 +59,37 @@ impl<'a> Lexer<'a> {
             if chunk.starts_with(|c: char| c.is_ascii_digit()) {
                 // number literal
                 let mut end = self.position;
-                for char in chunk.chars() {
+                let mut whole_chars = chunk.chars();
-                    if char.is_ascii_digit() {
+                while let Some(c) = whole_chars.next() {
+                    if c.is_ascii_digit() {
                         end += 1;
                     } else {
                         break;
                     }
                 }
-                Token::new(self.position, end, TokenKind::IntegerLiteral)
+
+                let mut fraction_chars = chunk.chars().skip(end - self.position);
+                if fraction_chars.next().map(|c| c == '.').unwrap_or(false) {
+                    let mut found_fraction = false;
+                    while let Some(c) = fraction_chars.next() {
+                        if c.is_ascii_digit() {
+                            end += 1;
+                            if !found_fraction {
+                                end += 1; // to account for decimal point
+                                found_fraction = true;
+                            }
+                        } else {
+                            break;
+                        }
+                    }
+                    if found_fraction {
+                        Token::new(self.position, end, TokenKind::DoubleLiteral)
+                    } else {
+                        Token::new(self.position, end, TokenKind::IntegerLiteral)
+                    }
+                } else {
+                    Token::new(self.position, end, TokenKind::IntegerLiteral)
+                }
             } else if chunk.starts_with("\"") {
                 // string literal
                 let mut end = self.position;
@@ -180,4 +203,40 @@ mod tests {
         let mut lexer = Lexer::new("extern");
         assert_next(&mut lexer, TokenKind::Extern, 6);
     }
+
+    #[test]
+    fn double_literal() {
+        let mut lexer = Lexer::new("123.45");
+        assert_next(&mut lexer, TokenKind::DoubleLiteral, 6);
+    }
+
+    #[test]
+    fn one_digit_whole_part_double() {
+        let mut lexer = Lexer::new("1.0");
+        assert_next(&mut lexer, TokenKind::DoubleLiteral, 3);
+    }
+
+    #[test]
+    fn two_digits_fraction_double() {
+        let mut lexer = Lexer::new("1.23");
+        assert_next(&mut lexer, TokenKind::DoubleLiteral, 4);
+    }
+
+    #[test]
+    fn int_literal() {
+        let mut lexer = Lexer::new("123");
+        assert_next(&mut lexer, TokenKind::IntegerLiteral, 3);
+    }
+
+    #[test]
+    fn doubles() {
+        let mut lexer = Lexer::new("println(1.23 + 2.34)");
+        assert_next(&mut lexer, TokenKind::Identifier, 7);
+        assert_next(&mut lexer, TokenKind::LeftParentheses, 1);
+        assert_next(&mut lexer, TokenKind::DoubleLiteral, 4);
+        assert_next(&mut lexer, TokenKind::Plus, 1);
+        assert_next(&mut lexer, TokenKind::DoubleLiteral, 4);
+        assert_next(&mut lexer, TokenKind::RightParentheses, 1);
+        assert!(lexer.next().is_none());
+    }
 }

dmc-lib/src/parser.rs

@@ -1,6 +1,7 @@
 use crate::ast::add_expression::AddExpression;
 use crate::ast::call::Call;
 use crate::ast::compilation_unit::CompilationUnit;
+use crate::ast::double_literal::DoubleLiteral;
 use crate::ast::expression::Expression;
 use crate::ast::expression_statement::ExpressionStatement;
 use crate::ast::extern_function::ExternFunction;
@@ -481,6 +482,15 @@ impl<'a> Parser<'a> {
                     source_range,
                 )))
             }
+            TokenKind::DoubleLiteral => {
+                let raw = self.token_text(&current);
+                let source_range = SourceRange::new(current.start(), current.end());
+                self.advance();
+                Ok(Expression::Double(DoubleLiteral::new(
+                    f64::from_str(raw).unwrap(),
+                    source_range,
+                )))
+            }
             TokenKind::String => {
                 let with_quotes = self.token_text(&current);
                 let source_range = SourceRange::new(current.start(), current.end());
@@ -509,7 +519,10 @@ impl<'a> Parser<'a> {
         if let Some(current) = &self.current {
             if matches!(
                 current.kind(),
-                TokenKind::IntegerLiteral | TokenKind::String | TokenKind::Identifier
+                TokenKind::IntegerLiteral
+                    | TokenKind::DoubleLiteral
+                    | TokenKind::String
+                    | TokenKind::Identifier
             ) {
                 arguments.append(&mut self.expression_list()?);
             }

dmc-lib/src/token.rs

@@ -33,6 +33,7 @@ pub enum TokenKind {
     Let,
     Equals,
     IntegerLiteral,
+    DoubleLiteral,
     LongLiteral,
     String,
     Extern,

dmc-lib/src/type_info.rs

@@ -7,6 +7,7 @@ use std::rc::Rc;
 pub enum TypeInfo {
     Any,
     Integer,
+    Double,
     String,
     Function(Rc<RefCell<FunctionSymbol>>),
     Void,
@@ -17,6 +18,7 @@ impl Display for TypeInfo {
         match self {
             TypeInfo::Any => write!(f, "Any"),
             TypeInfo::Integer => write!(f, "Int"),
+            TypeInfo::Double => write!(f, "Double"),
             TypeInfo::String => write!(f, "String"),
             TypeInfo::Function(function_symbol) => {
                 write!(f, "fn(")?;
@@ -36,6 +38,7 @@ impl TypeInfo {
         match declared_name {
             "Any" => TypeInfo::Any,
             "Int" => TypeInfo::Integer,
+            "Double" => TypeInfo::Double,
             "String" => TypeInfo::String,
             "Void" => TypeInfo::Void,
             _ => panic!("Unknown type: {}", declared_name),
@@ -48,6 +51,9 @@ impl TypeInfo {
             TypeInfo::Integer => {
                 matches!(other, TypeInfo::Integer)
             }
+            TypeInfo::Double => {
+                matches!(other, TypeInfo::Double)
+            }
             TypeInfo::String => {
                 matches!(other, TypeInfo::String)
             }
@@ -62,8 +68,15 @@ impl TypeInfo {
 
     pub fn can_add(&self, rhs: &Self) -> bool {
         match self {
-            TypeInfo::Integer => matches!(rhs, TypeInfo::Integer),
+            TypeInfo::Integer => {
-            TypeInfo::String => matches!(rhs, TypeInfo::String | TypeInfo::Integer),
+                matches!(rhs, TypeInfo::Integer | TypeInfo::Double | TypeInfo::String)
+            }
+            TypeInfo::Double => {
+                matches!(rhs, TypeInfo::Integer | TypeInfo::Double | TypeInfo::String)
+            }
+            TypeInfo::String => {
+                matches!(rhs, TypeInfo::Integer | TypeInfo::Double | TypeInfo::String)
+            }
             _ => false,
         }
     }
@@ -72,24 +85,41 @@ impl TypeInfo {
         match self {
             TypeInfo::Integer => match rhs {
                 TypeInfo::Integer => TypeInfo::Integer,
+                TypeInfo::Double => TypeInfo::Double,
                 TypeInfo::String => TypeInfo::String,
-                _ => panic!(
+                _ => panic!("Unsupported add: {} + {}.", self, rhs),
-                    "Adding things other than integers/strings to integer not yet supported."
+            },
-                ),
+            TypeInfo::Double => match rhs {
+                TypeInfo::Integer | TypeInfo::Double => TypeInfo::Double,
+                TypeInfo::String => TypeInfo::String,
+                _ => panic!("Unsupported add: {} + {}.", self, rhs),
             },
             TypeInfo::String => TypeInfo::String,
-            _ => panic!("Adding things other than integers and strings not yet supported"),
+            _ => panic!("Unsupported add: {} + {}.", self, rhs),
         }
     }
 
     pub fn can_subtract(&self, rhs: &Self) -> bool {
-        matches!(self, TypeInfo::Integer) && matches!(rhs, TypeInfo::Integer)
+        match self {
+            TypeInfo::Integer => {
+                matches!(rhs, TypeInfo::Integer | TypeInfo::Double)
+            }
+            TypeInfo::Double => {
+                matches!(rhs, TypeInfo::Integer | TypeInfo::Double)
+            }
+            _ => false,
+        }
     }
 
     pub fn subtract_result(&self, rhs: &Self) -> TypeInfo {
         match self {
             TypeInfo::Integer => match rhs {
                 TypeInfo::Integer => TypeInfo::Integer,
+                TypeInfo::Double => TypeInfo::Double,
+                _ => panic!(),
+            },
+            TypeInfo::Double => match rhs {
+                TypeInfo::Integer | TypeInfo::Double => TypeInfo::Double,
                 _ => panic!(),
             },
             _ => panic!(),

dvm-lib/src/instruction.rs

@@ -89,6 +89,7 @@ impl Display for Location {
 pub enum MoveOperand {
     Location(Location),
     Int(i32),
+    Double(f64),
     String(Rc<str>),
 }
 
@@ -101,6 +102,9 @@ impl Display for MoveOperand {
             MoveOperand::Int(i) => {
                 write!(f, "{}", i)
             }
+            MoveOperand::Double(d) => {
+                write!(f, "{}", d)
+            }
             MoveOperand::String(s) => {
                 write!(f, "{}", s)
             }
@@ -111,6 +115,7 @@ impl Display for MoveOperand {
 pub enum PushOperand {
     Location(Location),
     Int(i32),
+    Double(f64),
     String(Rc<str>),
 }
 
@@ -123,6 +128,9 @@ impl Display for PushOperand {
             PushOperand::Int(i) => {
                 write!(f, "{}", i)
             }
+            PushOperand::Double(d) => {
+                write!(f, "{}", d)
+            }
             PushOperand::String(s) => {
                 write!(f, "{}", s)
             }
@@ -133,6 +141,7 @@ impl Display for PushOperand {
 pub enum AddOperand {
     Location(Location),
     Int(i32),
+    Double(f64),
     String(Rc<str>),
 }
 
@@ -145,6 +154,9 @@ impl Display for AddOperand {
             AddOperand::Int(i) => {
                 write!(f, "{}", i)
             }
+            AddOperand::Double(d) => {
+                write!(f, "{}", d)
+            }
             AddOperand::String(s) => {
                 write!(f, "{}", s)
             }
@@ -155,6 +167,7 @@ impl Display for AddOperand {
 pub enum SubtractOperand {
     Location(Location),
     Int(i32),
+    Double(f64),
 }
 
 impl Display for SubtractOperand {
@@ -166,6 +179,9 @@ impl Display for SubtractOperand {
             SubtractOperand::Int(i) => {
                 write!(f, "{}", i)
             }
+            SubtractOperand::Double(d) => {
+                write!(f, "{}", d)
+            }
         }
     }
 }
@@ -173,6 +189,7 @@ impl Display for SubtractOperand {
 pub enum ReturnOperand {
     Location(Location),
     Int(i32),
+    Double(f64),
     String(Rc<str>),
 }
 
@@ -185,6 +202,9 @@ impl Display for ReturnOperand {
             ReturnOperand::Int(i) => {
                 write!(f, "{}", i)
             }
+            ReturnOperand::Double(d) => {
+                write!(f, "{}", d)
+            }
             ReturnOperand::String(s) => {
                 write!(f, "{}", s)
             }

dvm-lib/src/vm/instruction_helpers.rs

@@ -1,7 +1,30 @@
-use crate::instruction::SubtractOperand;
+use crate::instruction::{AddOperand, SubtractOperand};
 use crate::vm::CallFrame;
+use crate::vm::constant::Constant;
 use crate::vm::value::Value;
-use crate::vm::value_util::load_value;
+use crate::vm::value_util::{load_constant_value, load_value};
+use std::collections::HashMap;
+use std::rc::Rc;
+
+pub fn add_operand_to_value(
+    add_operand: &AddOperand,
+    registers: &[Value],
+    current_frame: &CallFrame,
+    constants: &HashMap<Rc<str>, Constant>,
+) -> Value {
+    match add_operand {
+        AddOperand::Location(location) => load_value(
+            registers,
+            current_frame.stack(),
+            current_frame.fp(),
+            location,
+        )
+        .clone(),
+        AddOperand::Int(i) => Value::Int(*i),
+        AddOperand::Double(d) => Value::Double(*d),
+        AddOperand::String(constant_name) => load_constant_value(constants, constant_name),
+    }
+}
 
 pub fn subtract_operand_to_value(
     subtract_operand: &SubtractOperand,
@@ -17,5 +40,6 @@ pub fn subtract_operand_to_value(
         )
         .clone(),
         SubtractOperand::Int(i) => Value::Int(*i),
+        SubtractOperand::Double(d) => Value::Double(*d),
     }
 }

dvm-lib/src/vm/mod.rs

@@ -1,8 +1,8 @@
-use crate::instruction::{AddOperand, Instruction, MoveOperand, PushOperand, ReturnOperand};
+use crate::instruction::{Instruction, MoveOperand, PushOperand, ReturnOperand};
 use crate::platform_function::PlatformFunction;
 use crate::vm::constant::Constant;
 use crate::vm::function::Function;
-use crate::vm::instruction_helpers::subtract_operand_to_value;
+use crate::vm::instruction_helpers::{add_operand_to_value, subtract_operand_to_value};
 use crate::vm::value::Value;
 use crate::vm::value_util::*;
 use std::collections::HashMap;
@@ -226,6 +226,7 @@ pub fn call<'a>(
                     )
                     .clone(),
                     MoveOperand::Int(i) => Value::Int(*i),
+                    MoveOperand::Double(d) => Value::Double(*d),
                     MoveOperand::String(constant_name) => {
                         load_constant_value(context.constants(), constant_name)
                     }
@@ -244,6 +245,7 @@ pub fn call<'a>(
                         location,
                     )
                     .clone(),
+                    PushOperand::Double(d) => Value::Double(*d),
                     PushOperand::Int(i) => Value::Int(*i),
                     PushOperand::String(constant_name) => {
                         load_constant_value(context.constants(), constant_name)
@@ -316,86 +318,74 @@ pub fn call<'a>(
 
             /* Add instructions */
             Instruction::Add(left_operand, right_operand, destination) => {
-                let left_value = match left_operand {
+                let left_value = add_operand_to_value(
-                    AddOperand::Location(location) => load_value(
+                    &left_operand,
-                        registers,
+                    registers,
-                        call_stack.top().stack(),
+                    call_stack.top(),
-                        call_stack.top().fp(),
+                    context.constants(),
-                        location,
+                );
-                    )
+
-                    .clone(),
+                let right_value = add_operand_to_value(
-                    AddOperand::Int(i) => Value::Int(*i),
+                    &right_operand,
-                    AddOperand::String(constant_name) => {
+                    registers,
-                        load_constant_value(context.constants(), constant_name)
+                    call_stack.top(),
-                    }
+                    context.constants(),
+                );
+
+                let result = match left_value {
+                    Value::Int(li) => match right_value {
+                        Value::Int(ri) => Value::Int(li + ri),
+                        Value::Double(rd) => Value::Double(li as f64 + rd),
+                        Value::String(rs) => Value::String(format!("{}{}", li, rs).into()),
+                        _ => panic!(
+                            "Attempt to add non-addable {:?} type to {:?}",
+                            right_value, left_value
+                        ),
+                    },
+                    Value::Double(ld) => match right_value {
+                        Value::Int(ri) => Value::Double(ld + ri as f64),
+                        Value::Double(rd) => Value::Double(ld + rd),
+                        Value::String(rs) => Value::String(format!("{}{}", ld, rs).into()),
+                        _ => panic!(
+                            "Attempt to add non-addable {:?} type to {:?}",
+                            right_value, left_value
+                        ),
+                    },
+                    Value::String(ref ls) => match right_value {
+                        Value::Int(ri) => Value::String(format!("{}{}", ls, ri).into()),
+                        Value::Double(rd) => Value::String(format!("{}{}", ls, rd).into()),
+                        Value::String(rs) => Value::String(format!("{}{}", ls, rs).into()),
+                        _ => panic!(
+                            "Attempt to add non-addable {:?} type to {:?}",
+                            right_value, left_value
+                        ),
+                    },
+                    _ => panic!("Attempt to add with non-addable type: {:?}", left_value),
                 };
 
-                let right_value = match right_operand {
+                put_value(registers, call_stack.top_mut(), destination, result);
-                    AddOperand::Location(location) => load_value(
-                        registers,
-                        call_stack.top().stack(),
-                        call_stack.top().fp(),
-                        location,
-                    )
-                    .clone(),
-                    AddOperand::Int(i) => Value::Int(*i),
-                    AddOperand::String(constant_name) => {
-                        load_constant_value(context.constants(), constant_name)
-                    }
-                };
-
-                if let Value::Int(left) = left_value {
-                    if let Value::Int(right) = right_value {
-                        let result = left + right;
-                        put_value(
-                            registers,
-                            call_stack.top_mut(),
-                            destination,
-                            Value::Int(result),
-                        );
-                    } else if let Value::String(s) = right_value {
-                        let result = format!("{}{}", left, s);
-                        put_value(
-                            registers,
-                            call_stack.top_mut(),
-                            destination,
-                            Value::String(result.into()),
-                        );
-                    } else {
-                        panic!("Attempt to add on non-addable type: {:?}", right_value);
-                    }
-                } else if let Value::String(left) = left_value {
-                    if let Value::Int(right) = right_value {
-                        let result = format!("{}{}", left, right);
-                        put_value(
-                            registers,
-                            call_stack.top_mut(),
-                            destination,
-                            Value::String(result.into()),
-                        );
-                    } else if let Value::String(right) = right_value {
-                        let result = format!("{}{}", left, right);
-                        put_value(
-                            registers,
-                            call_stack.top_mut(),
-                            destination,
-                            Value::String(result.into()),
-                        );
-                    } else {
-                        panic!("Attempt to add on non-addable type: {:?}", right_value);
-                    }
-                } else {
-                    panic!("Attempt to add on non-addable type: {:?}", left_value);
-                }
 
                 call_stack.top_mut().increment_ip();
             }
+
             Instruction::Subtract(left_operand, right_operand, destination) => {
-                let left = subtract_operand_to_value(left_operand, registers, call_stack.top())
+                let left = subtract_operand_to_value(left_operand, registers, call_stack.top());
-                    .unwrap_int();
+                let right = subtract_operand_to_value(right_operand, registers, call_stack.top());
-                let right = subtract_operand_to_value(right_operand, registers, call_stack.top())
+
-                    .unwrap_int();
+                let result = match left {
-                let result = Value::Int(left - right);
+                    Value::Int(li) => match right {
+                        Value::Int(ri) => Value::Int(li - ri),
+                        Value::Double(rd) => Value::Double(li as f64 - rd),
+                        _ => panic!("Attempt to subtract {:?} from {:?}", right, left),
+                    },
+                    Value::Double(ld) => match right {
+                        Value::Int(ri) => Value::Double(ld - ri as f64),
+                        Value::Double(rd) => Value::Double(ld - rd),
+                        _ => panic!("Attempt to subtract {:?} from {:?}", right, left),
+                    },
+                    _ => panic!("Attempt to subtract {:?} from {:?}", right, left),
+                };
+
                 put_value(registers, call_stack.top_mut(), destination, result);
                 call_stack.top_mut().increment_ip();
             }
@@ -420,6 +410,7 @@ pub fn call<'a>(
                     )
                     .clone(),
                     ReturnOperand::Int(i) => Value::Int(*i),
+                    ReturnOperand::Double(d) => Value::Double(*d),
                     ReturnOperand::String(constant_name) => {
                         load_constant_value(context.constants(), constant_name)
                     }

dvm-lib/src/vm/value.rs

@@ -1,9 +1,10 @@
 use std::fmt::{Display, Formatter};
 use std::rc::Rc;
 
-#[derive(Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq)]
 pub enum Value {
     Int(i32),
+    Double(f64),
     String(Rc<str>),
     Null,
 }
@@ -22,6 +23,13 @@ impl Value {
         }
     }
 
+    pub fn unwrap_double(&self) -> f64 {
+        match self {
+            Value::Double(d) => *d,
+            _ => panic!("Attempt to unwrap Double; found {:?}", self),
+        }
+    }
+
     pub fn unwrap_string(&self) -> &Rc<str> {
         match self {
             Value::String(s) => s,
@@ -36,6 +44,9 @@ impl Display for Value {
             Value::Int(i) => {
                 write!(f, "{}", i)
             }
+            Value::Double(d) => {
+                write!(f, "{}", d)
+            }
             Value::String(s) => {
                 write!(f, "{}", s)
             }

e2e-tests/src/lib.rs

@@ -24,7 +24,7 @@ mod e2e_tests {
         panic!("There were diagnostics.");
     }
 
-    fn assert_result(input: &str, function_name: &str, arguments: &[Value], expected_value: Value) {
+    fn prepare_context(input: &str) -> DvmContext {
         let parse_result = parse_compilation_unit(input);
         let mut compilation_unit = match parse_result {
             Ok(compilation_unit) => compilation_unit,
@@ -82,17 +82,29 @@ mod e2e_tests {
             );
         }
 
+        dvm_context
+    }
+
+    fn get_result(
+        dvm_context: &DvmContext,
+        function_name: &str,
+        arguments: &[Value],
+    ) -> Option<Value> {
         let mut registers: Vec<Value> = vec![Value::Null; REGISTER_COUNT];
         let mut call_stack = CallStack::new();
 
-        let result = call(
+        call(
             &dvm_context,
             &mut registers,
             &mut call_stack,
             function_name,
             &arguments,
-        );
+        )
-        match result {
+    }
+
+    fn assert_result(input: &str, function_name: &str, arguments: &[Value], expected_value: Value) {
+        let context = prepare_context(input);
+        match get_result(&context, function_name, arguments) {
             None => panic!("Call returned no value"),
             Some(result_value) => {
                 assert_eq!(result_value, expected_value);
@@ -136,6 +148,58 @@ mod e2e_tests {
     fn simple_subtract() {
         assert_result("fn sub() -> Int 3 - 2 end", "sub", &vec![], Value::Int(1))
     }
+
+    #[test]
+    fn add_two_doubles() {
+        assert_result(
+            "fn add(a: Double, b: Double) -> Double a + b end",
+            "add",
+            &vec![Value::Double(1.23), Value::Double(1.23)],
+            Value::Double(1.23 + 1.23),
+        );
+    }
+
+    #[test]
+    fn add_two_double_variables() {
+        assert_result(
+            "
+            fn add() -> Double
+                let a = 1.0
+                let b = 2.0
+                a + b
+            end
+            ",
+            "add",
+            &vec![Value::Double(1.0), Value::Double(2.0)],
+            Value::Double(3.0),
+        );
+    }
+
+    #[test]
+    fn subtract_two_doubles() {
+        assert_result(
+            "fn subtract(a: Double, b: Double) -> Double a - b end",
+            "subtract",
+            &vec![Value::Double(3.0), Value::Double(2.0)],
+            Value::Double(1.0),
+        );
+    }
+
+    #[test]
+    fn subtract_two_double_variables() {
+        assert_result(
+            "
+            fn subtract() -> Double
+                let a = 3.0
+                let b = 2.0
+                a - b
+            end
+            ",
+            "subtract",
+            &vec![],
+            Value::Double(1.0),
+        )
+    }
 }
 
 #[cfg(test)]

examples/doubles.dm

@@ -0,0 +1,9 @@
+extern fn println(message: Any) -> Void
+
+fn main()
+    println(1.23 + 2.34)
+    println(1 + 2.0)
+    println(2.0 + 1)
+    println("hello " + 2.34)
+    println(2.34 + " hello")
+end