diff --git a/definitions/example.yml b/definitions/example.yml
new file mode 100644
index 0000000..bbb0f94
--- /dev/null
+++ b/definitions/example.yml
@@ -0,0 +1,21 @@
+---
+entities:
+  - name: Player
+    package: org.hexalite.generation.entity
+    feature_flag: example
+    fields:
+      a:
+        kind:
+          kotlin: java.util.UUID
+          rust: String
+        sql: 'uuid().not_null().primary_key()'
+      test_c:
+        kind:
+          kotlin: Int
+          rust: u32
+        sql: 'integer().not_null().default(0)'
+      hello_d:
+        kind:
+          kotlin: String
+          rust: String
+        sql: 'varchar(255).not_null().default("")'
diff --git a/definitions/rust/Cargo.toml b/definitions/rust/Cargo.toml
index 1bb156f..6910ce2 100644
--- a/definitions/rust/Cargo.toml
+++ b/definitions/rust/Cargo.toml
@@ -13,3 +13,4 @@ syn = "^1"
 quote = "^1"
 serde = { version = "^1", features = ["derive"] }
 serde_yaml = "^0.8"
+home = "^0"
\ No newline at end of file
diff --git a/definitions/rust/generated/Cargo.toml b/definitions/rust/generated/Cargo.toml
index e9e9bfe..d20ec50 100644
--- a/definitions/rust/generated/Cargo.toml
+++ b/definitions/rust/generated/Cargo.toml
@@ -4,5 +4,9 @@ version = "0.1.0"
 edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+[features]
+example = []
+default = ["example"]
 
 [dependencies]
+definitions-generator = { path = "../" }
\ No newline at end of file
diff --git a/definitions/rust/generated/src/lib.rs b/definitions/rust/generated/src/lib.rs
index 8b13789..efb10da 100644
--- a/definitions/rust/generated/src/lib.rs
+++ b/definitions/rust/generated/src/lib.rs
@@ -1 +1,2 @@
-
+#[cfg(feature = "example")]
+definitions_generator::generate_entity_definitions!("definitions/example.yml");
diff --git a/definitions/rust/src/lib.rs b/definitions/rust/src/lib.rs
index 55a728b..763dcd4 100644
--- a/definitions/rust/src/lib.rs
+++ b/definitions/rust/src/lib.rs
@@ -1 +1,69 @@
-mod specification;
\ No newline at end of file
+use std::fs;
+
+use proc_macro::TokenStream;
+use quote::format_ident;
+use specification::SpecificationRoot;
+
+mod specification;
+
+#[proc_macro]
+pub fn generate_entity_definitions(item: TokenStream) -> TokenStream {
+    let mut path = item.to_string();
+    path.pop();
+    path.remove(0);
+    
+    let code = path
+        .split("|")
+        .map(|path| {
+            let home = home::home_dir().expect("Could not find home directory");
+
+            let root = home
+                .join(".hexalite")
+                .join("dev")
+                .canonicalize()
+                .expect("Could not find ~/.hexalite/dev directory");
+
+            let file = root.join(path);
+            let file = fs::read_to_string(&file)
+                .expect(format!("Nao achou em {}", file.display()).as_str());
+
+            let specification: SpecificationRoot =
+                serde_yaml::from_str(file.as_str()).expect("Could not parse specification");
+
+            let quotes = specification
+                .entities
+                .iter()
+                .map(|specification| {
+                    let struct_fields_name = specification
+                        .fields
+                        .iter()
+                        .map(|(name, _)| format_ident!("{}", name.clone().trim().to_string()))
+                        .collect::<Vec<_>>();
+                    let struct_fields_kind = specification
+                        .fields
+                        .iter()
+                        .map(|(_, field)| format_ident!("{}", field.kind.rust.trim().to_string()))
+                        .collect::<Vec<_>>();
+                    let name = format_ident!("{}", specification.name.trim());
+
+                    quote::quote! {
+                        #[derive(Debug, Clone)]
+                        pub struct #name {
+                            #(pub #struct_fields_name: #struct_fields_kind),*
+                        }
+                    }
+                })
+                .collect::<Vec<_>>();
+
+            quote::quote! {
+                #(#quotes)
+                *
+            }
+        })
+        .collect::<Vec<_>>();
+
+    TokenStream::from(quote::quote! {
+        #(#code)
+        *
+    })
+}
diff --git a/definitions/rust/src/specification.rs b/definitions/rust/src/specification.rs
index bb42606..ffca736 100644
--- a/definitions/rust/src/specification.rs
+++ b/definitions/rust/src/specification.rs
@@ -9,21 +9,27 @@ use serde::Deserialize;
 
 #[derive(Debug, Clone, Deserialize)]
 pub struct SpecificationRoot {
-    pub name: String,
-    pub location: RustAndKotlinType,
-    pub feature_flag: String,
-    pub fields: HashMap<String, SpecificationField>
+    pub entities: Vec<SpecificationEntity>
 }
 
 #[derive(Debug, Clone, Deserialize)]
-pub struct RustAndKotlinType {
-    pub rust: String,
-    pub kotlin: String
+pub struct SpecificationEntity {
+    pub name: String,
+    #[serde(rename = "package")]
+    pub kotlin_package: String,
+    pub feature_flag: String,
+    pub fields: HashMap<String, SpecificationField>
 }
 
 #[derive(Debug, Clone, Deserialize)]
 pub struct SpecificationField {
-    pub kind: RustAndKotlinType,
+    pub kind: SpecificationFieldKind,
     #[serde(default)]
     pub sql: Option<String>,
 }
+
+#[derive(Debug, Clone, Deserialize)]
+pub struct SpecificationFieldKind {
+    pub rust: String,
+    pub kotlin: String
+}