Working on a simple LISP/scheme interpreter.

1 files changed, 34 insertions, 0 deletions

diff --git a/src/lib/eval/arith.rs b/src/lib/eval/arith.rs
new file mode 100644
index 0000000..fae69de
--- /dev/null
+++ b/src/lib/eval/arith.rs
@@ -0,0 +1,34 @@
+use std::ops::Add;
+use super::super::types::Type;
+use super::super::types::Type::*;
+use super::super::types::Number;
+
+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())
+        }
+    }
+}