1 files changed, 50 insertions, 0 deletions
diff --git a/src/simple.rs b/src/simple.rs
new file mode 100644
index 0000000..f71da46
--- /dev/null
+++ b/src/simple.rs
@@ -0,0 +1,50 @@
+// Simple bidirectional type checking
+
+use crate::ast::*;
+
+pub fn infer(context: Context, expression: Expression) {
+    todo!();
+}
+
+pub fn check(context: Context, expression: Expression) {
+    todo!();
+}
+
+/// Evaluates an expression given a context (of variables) to a term.
+/// Panics on non-evaluatable code.
+pub fn execute(context: Context, expression: Expression) -> Term {
+    match expression {
+        Expression::Annotation { expr, .. } => return execute(context, *expr),
+        Expression::Constant { term } => return term,
+        Expression::Variable { id } => return context[&id],
+        Expression::Abstraction { .. } => panic!(),
+        Expression::Application { func, arg } => {
+            match *func {
+                Expression::Abstraction { param, func } => {
+                    let mut context = context;
+                    context.insert(param, execute(context.clone(), *arg));
+                    return execute(context, *func);
+                },
+                _ => panic!()
+            }
+        },
+        Expression::Conditional { if_cond, if_then, if_else } => {
+            match execute(context.clone(), *if_cond).val {
+                1 => execute(context, *if_then),
+                0 => execute(context, *if_else),
+                _ => panic!()
+            }
+        },
+    }
+}
+
+// intentionally small: i want to run into errors
+/// assumption: the count is instantiated to zero
+fn uniquify(count: &mut u8) -> String {
+    *count += 1;
+    if *count == 0 {
+        panic!("we've overflowed!");
+    } else {
+        return String::from(format!("{:X}", count));
+    }
+}