diff --git a/src/compilation/mod.rs b/src/compilation/mod.rs
index 5995aac..e147235 100644
--- a/src/compilation/mod.rs
+++ b/src/compilation/mod.rs
@@ -42,6 +42,10 @@ pub enum CompileError {
         expected: Type,
         found: Type,
     },
+    InvalidFormulaType {
+        expected: Type,
+        found: Type,
+    },
     VariableNotFound(String),
     ConditionMustBeBool,
     ConditionalBranchesMustHaveSameType(Type, Type),
diff --git a/src/lib.rs b/src/lib.rs
index 5a18d14..7552a39 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -3,8 +3,8 @@ use chrono::NaiveDate;
 use formula_writer::FormulaWriter;
 pub use object::FormulaObject;
 use std::sync::Arc;
-use types::Type;
-use value::Value;
+pub use types::Type;
+pub use value::Value;
 
 mod array_formula;
 mod bool_formula;