Add type checking on builtins as a call arg

This is a runtime error currently but can be pushed back to a compiler error with some work

Author: kyleect

spec/invalid/not_id.expr

@@ -0,0 +1 @@
+(not id)

spec/invalid/not_id.expr.disassembled

@@ -0,0 +1,5 @@
+VERSION 0700
+----
+0000 GET BUILTIN        16 == 'not'
+0003 GET BUILTIN         0 == 'id'
+0006 CALL             (1 args)

spec/invalid/not_id.expr.interpreted

@@ -0,0 +1,11 @@
+[
+    (
+        RuntimeError(
+            TypeMismatch {
+                expected: Bool,
+                actual: Fn(Value) -> Value,
+            },
+        ),
+        0..0,
+    ),
+]

src/value.rs

@@ -42,8 +42,8 @@ impl Value {
                 RuntimeError::TypeMismatch {
                     expected: Type::Fn {
                         args: vec![],
-                        variadic_arg: Some(Type::Unknown.into()),
-                        returns: Type::Unknown.into(),
+                        variadic_arg: Some(Type::Value.into()),
+                        returns: Type::Value.into(),
                     },
                     actual: self.get_type(),
                 }
@@ -140,8 +140,8 @@ mod tests {
                 RuntimeError::TypeMismatch {
                     expected: Type::Fn {
                         args: vec![],
-                        variadic_arg: Some(Type::Unknown.into()),
-                        returns: Type::Unknown.into()
+                        variadic_arg: Some(Type::Value.into()),
+                        returns: Type::Value.into()
                     },
                     actual: Type::String
                 }
@@ -174,8 +174,8 @@ mod tests {
                 RuntimeError::TypeMismatch {
                     expected: Type::Fn {
                         args: vec![],
-                        variadic_arg: Some(Type::Unknown.into()),
-                        returns: Type::Unknown.into()
+                        variadic_arg: Some(Type::Value.into()),
+                        returns: Type::Value.into()
                     },
                     actual: Type::Bool
                 }