diff --git a/src/compile.rs b/src/compile.rs
index f6f0e1c..9b0ad46 100644
--- a/src/compile.rs
+++ b/src/compile.rs
@@ -109,6 +109,35 @@ pub enum Mode {
     Single,
 }
 
+impl std::str::FromStr for Mode {
+    type Err = ModeParseError;
+    fn from_str(s: &str) -> Result<Self, ModeParseError> {
+        match s {
+            "exec" => Ok(Mode::Exec),
+            "eval" => Ok(Mode::Eval),
+            "single" => Ok(Mode::Single),
+            _ => Err(ModeParseError { _priv: () }),
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct ModeParseError {
+    _priv: (),
+}
+
+impl std::fmt::Display for ModeParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, r#"mode should be "exec", "eval", or "single""#)
+    }
+}
+
+#[derive(Clone, Copy)]
+enum EvalContext {
+    Statement,
+    Expression,
+}
+
 pub(crate) type Label = usize;
 
 impl<O> Default for Compiler<O>