1 files changed, 58 insertions, 25 deletions

diff --git a/src/lib/eval/arith.rs b/src/lib/eval/arith.rs
index fae69de..fe3a06b 100644
--- a/src/lib/eval/arith.rs
+++ b/src/lib/eval/arith.rs
@@ -1,34 +1,67 @@
-use std::ops::Add;
+use std::ops::{Add, Sub, Mul, Div};
 use super::super::types::Type;
-use super::super::types::Type::*;
 use super::super::types::Number;
 
+fn apply_arithmetic(
+    func_i: fn(isize, isize) -> isize,
+    func_f: fn(f32, f32) -> f32,
+    operand_a: &Type,
+    operand_b: &Type) -> Result<Type, String> {
+
+    match (operand_a, operand_b) {
+        (Type::Bool(_), _) | (_, Type::Bool(_)) |
+        (Type::Str(_), _) | (_, Type::Str(_)) |
+        (Type::Operator(_), _) | (_, Type::Operator(_)) => {
+            Err("Incompatible types".to_string())
+        },
+
+        (Type::Number(Number::Int(i)), Type::Number(Number::Float(f))) |
+        (Type::Number(Number::Float(f)), Type::Number(Number::Int(i))) => {
+            Ok(Type::Number(Number::Float(func_f(*f, *i as f32))))
+        },
+
+        (Type::Number(Number::Int(a)), Type::Number(Number::Int(b))) => {
+            Ok(Type::Number(Number::Int(func_i(*a, *b))))
+        },
+
+        (Type::Number(Number::Float(a)), Type::Number(Number::Float(b))) => {
+            Ok(Type::Number(Number::Float(func_f(*a, *b))))
+        },
+
+        (Type::Symbol(_), Type::Number(_)) |
+        (Type::Number(_), Type::Symbol(_)) |
+        (Type::Symbol(_), Type::Symbol(_)) => Err("Not yet implemented".to_string())
+    }
+}
+
 impl Add for Type {
     type Output = Result<Type, String>;
 
     fn add(self, other: Type) -> Result<Type, String> {
-        match (self, other) {
-            (Bool(_), _) | (_, Bool(_)) |
-            (Str(_), _) | (_, Str(_)) |
-            (Operator(_), _) | (_, Operator(_)) => {
-                Err("Cannot add these types".to_string())
-            },
-            (Number(Number::Int(i)), Number(Number::Float(f))) |
-            (Number(Number::Float(f)), Number(Number::Int(i))) => {
-                Ok(Number(Number::Float(f + i as f32)))
-            },
-
-            (Number(Number::Int(a)), Number(Number::Int(b))) => {
-                Ok(Number(Number::Int(a + b)))
-            },
-
-            (Number(Number::Float(a)), Number(Number::Float(b))) => {
-                Ok(Number(Number::Float(a + b)))
-            },
-
-            (Symbol(_), Number(_)) |
-            (Number(_), Symbol(_)) |
-            (Symbol(_), Symbol(_)) => Err("Not yet implemented".to_string())
-        }
+        apply_arithmetic(|a, b| a + b, |a, b| a + b, &self, &other)
+    }
+}
+
+impl Sub for Type {
+    type Output = Result<Type, String>;
+
+    fn sub(self, other: Type) -> Result<Type, String> {
+        apply_arithmetic(|a, b| a - b, |a, b| a - b, &self, &other)
+    }
+}
+
+impl Mul for Type {
+    type Output = Result<Type, String>;
+
+    fn mul(self, other: Type) -> Result<Type, String> {
+        apply_arithmetic(|a, b| a * b, |a, b| a * b, &self, &other)
+    }
+}
+
+impl Div for Type {
+    type Output = Result<Type, String>;
+
+    fn div(self, other: Type) -> Result<Type, String> {
+        apply_arithmetic(|a, b| a / b, |a, b| a / b, &self, &other)
     }
 }