diff --git a/Readme.org b/Readme.org
index 6e8e41e..c1cda85 100644
--- a/Readme.org
+++ b/Readme.org
@@ -148,8 +148,8 @@ Will need a concatenate function for tables
 *** TODO Main shell calls Load function on arg and exits
 *** TODO Can enter multiple lines of text, with formatting in repl
 *** TODO arithmetic operations
-**** TODO typecast (int)
-**** TODO typecast (float)
+**** DONE typecast (int)
+**** DONE typecast (float)
 **** DONE add
 **** DONE sub
 **** DONE div
diff --git a/src/stl.rs b/src/stl.rs
index 078900f..d0a7ff2 100644
--- a/src/stl.rs
+++ b/src/stl.rs
@@ -228,6 +228,28 @@ pub fn static_stdlib(syms: &mut SymTable) -> Result<(), String> {
         },
     );
 
+    syms.insert(
+        "int".to_string(),
+        Symbol {
+            name: String::from("int"),
+            args: Args::Lazy(1),
+            conditional_branches: false,
+            docs: math::INTCAST_DOCSTRING.to_string(),
+            value: ValueType::Internal(Rc::new(math::intcast_callback)),
+        },
+    );
+
+    syms.insert(
+        "float".to_string(),
+        Symbol {
+            name: String::from("float"),
+            args: Args::Lazy(1),
+            conditional_branches: false,
+            docs: math::FLOATCAST_DOCSTRING.to_string(),
+            value: ValueType::Internal(Rc::new(math::floatcast_callback)),
+        },
+    );
+
     Ok(())
 }
 
diff --git a/src/stl/math.rs b/src/stl/math.rs
index 1f1e8e2..c08cba0 100644
--- a/src/stl/math.rs
+++ b/src/stl/math.rs
@@ -125,3 +125,45 @@ pub fn mul_callback(ast: &Seg, _: &mut SymTable) -> Result<Ctr, String> {
         Ok(res)
     }
 }
+
+pub const INTCAST_DOCSTRING: &str = "takes a single arg and attempts to cast it to an Integer.
+This will work for a float or a potentially a string.
+If the cast to Integer fails, it will return Nothing and print an error.
+Casting a float to an int will drop its decimal.";
+
+pub fn intcast_callback(ast: &Seg, _: &mut SymTable) -> Result<Ctr, String> {
+    // special case for float
+    if let Ctr::Float(f) = *ast.car {
+        Ok(Ctr::Integer(f as i128))
+    } else if let Ctr::String(ref s) = *ast.car {
+        let int = str::parse::<i128>(s);
+        if int.is_err() {
+            Err(int.err().unwrap().to_string())
+        } else {
+            Ok(Ctr::Integer(int.ok().unwrap()))
+        }
+    } else {
+        Err("int cast only takes a float or a string".to_string())
+    }
+}
+
+pub const FLOATCAST_DOCSTRING: &str = "takes a single arg and attempts to cast it to a float.
+This will work for an integer or potentially a string.
+If the cast to integer fails, this function will return nothing and print an error.
+Casting an integer to a float can result in bad behaviour since float nodes are based on 64bit floats and int nodes are based on 128 bit integers.";
+
+pub fn floatcast_callback(ast: &Seg, _: &mut SymTable) -> Result<Ctr, String> {
+    // special case for float
+    if let Ctr::Integer(i) = *ast.car {
+        Ok(Ctr::Float(i as f64))
+    } else if let Ctr::String(ref s) = *ast.car {
+        let int = str::parse::<f64>(&s);
+        if int.is_err() {
+            Err(int.err().unwrap().to_string())
+        } else {
+            Ok(Ctr::Float(int.ok().unwrap()))
+        }
+    } else {
+        Err("float cast only takes an integer or a string".to_string())
+    }
+}
diff --git a/tests/test_lib_math.rs b/tests/test_lib_math.rs
index f208c7d..9709853 100644
--- a/tests/test_lib_math.rs
+++ b/tests/test_lib_math.rs
@@ -81,4 +81,68 @@ mod math_lib_tests {
             result.to_string(),
         );
     }
+
+    #[test]
+    fn test_float_to_int() {
+        let document = "(int 10.5)";
+        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_string_to_int() {
+        let document = "(int '10')";
+        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_int_to_float() {
+        let document = "(float 10)";
+        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_string_to_float() {
+        let document = "(float '10.3')";
+        let result = "10.3";
+
+        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(),
+        );
+    }
 }