add basic arithmatic operations

Signed-off-by: Ava Hahn <ava@aidanis.online>

tests/test_lib_math.rs

@@ -0,0 +1,84 @@
+mod math_lib_tests {
+    use relish::ast::{eval, lex, SymTable};
+    use relish::stdlib::{dynamic_stdlib, static_stdlib};
+
+    #[test]
+    fn test_add_chain() {
+        let document = "(add 1 2 3 4)";
+        let result = "10";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms).unwrap();
+        dynamic_stdlib(&mut syms).unwrap();
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_add_chain_mixed() {
+        let document = "(add 1 2.2 3 4)";
+        let result = "10.2";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms).unwrap();
+        dynamic_stdlib(&mut syms).unwrap();
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_mul_chain() {
+        let document = "(mul 1 2 3 4)";
+        let result = "24";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms).unwrap();
+        dynamic_stdlib(&mut syms).unwrap();
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_sub_chain() {
+        let document = "(sub 1 2.2 3 4)";
+        let result = "-8.2";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms).unwrap();
+        dynamic_stdlib(&mut syms).unwrap();
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_div() {
+        let document = "(div 10 5)";
+        let result = "2";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms).unwrap();
+        dynamic_stdlib(&mut syms).unwrap();
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+}