diff --git a/crates/analyzer/src/transpiler.rs b/crates/analyzer/src/transpiler.rs
index 347267a..66a316c 100644
--- a/crates/analyzer/src/transpiler.rs
+++ b/crates/analyzer/src/transpiler.rs
@@ -3,10 +3,7 @@ use std::{
     path::{Path, PathBuf},
 };
 
-use mist_parser::{
-    ast::{Identifier, TopLevel, Visibility},
-    error::ParseError,
-};
+use mist_parser::{ast::TopLevel, error::ParseError};
 
 pub fn build(root: &PathBuf) {
     let src_dir = root.join("src");
@@ -136,9 +133,7 @@ pub fn transpile_file(path: &Path, output_path: &Path) -> Result<(), String> {
     });
 
     // If parsing fails, return the error string back gracefully so the LSP can show it
-    let ast = parser_result
-        .map_err(|e| format!("parse failed in {}:\n{}", path.display(), e))?
-        .1;
+    let ast = parser_result.map_err(|e| format!("parse failed in {}:\n{}", path.display(), e))?;
 
     let mut gc = mist_codegen::RustCodegen::new();
     let output = gc.generate(ast);
@@ -149,12 +144,10 @@ pub fn transpile_file(path: &Path, output_path: &Path) -> Result<(), String> {
     Ok(())
 }
 
-pub fn transpile_text<'a>(
-    source: &'a str,
-) -> Result<String, ParseError<'a, (Option<(Visibility, Identifier)>, Vec<TopLevel>)>> {
+pub fn transpile_text<'a>(source: &'a str) -> Result<String, ParseError<'a, Vec<TopLevel>>> {
     let mut gc = mist_codegen::RustCodegen::new();
 
-    Ok(gc.generate(mist_parser::parse(&source)?.1))
+    Ok(gc.generate(mist_parser::parse(&source)?))
 }
 
 fn should_skip(source: &Path, output: &Path) -> bool {
diff --git a/crates/mist-api/src/modules.mist b/crates/mist-api/src/modules.mist
index a6ad128..ea1c3c4 100644
--- a/crates/mist-api/src/modules.mist
+++ b/crates/mist-api/src/modules.mist
@@ -77,11 +77,17 @@ pub class Module {
         }
     }
 
-    pub fn output_path(*self, parent_dir *PathBuf) PathBuf {
-        if self.path.is_dir() || self.is_package() {
-            parent_dir.join(&self.name).join("mod.rs")
+    pub fn output_path(*self, parent_dir *PathBuf, curr_mod_decl *Option<[mist_parser::ast::Visibility, mist_parser::ast::Identifier]>) PathBuf {
+        let name = if let Some[[_, name]] = curr_mod_decl {
+            &name.0
         } else {
-            parent_dir.join(&self.name).with_extension("rs")
+            &self.name
+        };
+
+        if self.path.is_dir() || self.is_package() {
+            parent_dir.join(name).join("mod.rs")
+        } else {
+            parent_dir.join(name).with_extension("rs")
         }
     }
 }
diff --git a/crates/mist-api/src/transpiler.mist b/crates/mist-api/src/transpiler.mist
index 37551fa..ba66a5f 100644
--- a/crates/mist-api/src/transpiler.mist
+++ b/crates/mist-api/src/transpiler.mist
@@ -84,7 +84,7 @@ pub fn transpile() PathBuf {
 }
 
 impl modules::Module {
-    fn transpile(*self, parent_dir *PathBuf, config *mut MistConfig) String {
+    fn transpile(*self, parent_dir *PathBuf, config *mut MistConfig) [bool, String] {
         if !self.path.is_dir() && self.path.extension().and_then(fn(v) -> v.to_str()) != Some("mist") {
             let file_name = self.path.file_name()
                 .and_then(fn(s) -> s.to_str())
@@ -92,19 +92,25 @@ impl modules::Module {
 
             fs::copy(&self.path, parent_dir.join(&file_name)).expect("Failed to copy SideFile");
 
-            return String::new();
+            return (true, String::new());
         }
 
-        let dir = self.output_dir(&parent_dir);
-        let output_file = self.output_path(&parent_dir);
+        let dir = self.output_dir(parent_dir);
 
         let _ = fs::create_dir_all(&dir);
 
         let mut output = String::new();
 
+        let mut child_changed = false;
+
         for child in &self.children {
             if !config.should_ignore(&child.path) {
-                output.push_str(&child.transpile(&dir, config));
+                let out = child.transpile(&dir, config);
+                if out.0 {
+                    child_changed = true;
+                }
+
+                output.push_str(&out.1);
             }
         }
 
@@ -114,13 +120,15 @@ impl modules::Module {
             output.push_str(&config.main_mods)
         }
 
-        self.write_transpile(output, output_file)
+        self.write_transpile(output, parent_dir, child_changed)
     }
 
-    fn write_transpile(*self, output String, output_file PathBuf) String {
+    fn write_transpile(*self, output String, parent_dir *PathBuf, child_changed bool) [bool, String] {
         if self.path.is_dir() {
+            let output_file = self.output_path(parent_dir, &None);
+
             if output.len() == 0 {
-                return String::new();
+                return (true, String::new());
             }
 
             let res = fs::write(&output_file, output);
@@ -135,26 +143,66 @@ impl modules::Module {
                 process::exit(1);
             }
 
-            format!("pub mod {};\n", self.name)
+            (false, format!("pub mod {};\n", self.name))
         } else {
-            transpile_file(&self.path, output_file, &output)
+            let source = match fs::read_to_string(&self.path) {
+                Ok[s] => s;
+                Err[e] => {
+                    eprintln!("error: failed to read file {}\n  {}", self.path.display(), e);
+
+                    process::exit(1);
+                }
+            };
+
+            let curr_mod_decl = mist_parser::parse_module(&source).expect("Failed parsing module");
+
+            let output_file = self.output_path(parent_dir, &curr_mod_decl);
+
+            let should_change = is_source_newer(&self.path, &output_file).expect("Failed to cache");
+
+            if should_change || child_changed {
+                transpile_file(&self.path, &source, output_file, &output, &curr_mod_decl);
+            }
+
+            (should_change, if let Some[[vis, name]] = &curr_mod_decl {
+                format!("{}mod {};\n", vis.get_rust(), name.get_rust())
+            } else {
+                String::new()
+            })
         }
     }
 }
 
-fn transpile_file(path *PathBuf, mut output_file PathBuf, mod_decl *str) String {
-    let source = match fs::read_to_string(&path) {
-        Ok[s] => s;
-        Err[e] => {
-            eprintln!("error: failed to read file {}\n  {}", path.display(), e);
+fn is_source_newer(source *Path, output *Path) std::io::Result<bool> {
+    if !output.exists() {
+        return Ok(true);
+    }
 
-            process::exit(1);
+    let source_time = fs::metadata(source)?.modified()?;
+    let output_time = fs::metadata(output)?.modified()?;
+
+    Ok(source_time > output_time)
+}
+
+fn transpile_file(path *PathBuf, source *str, mut output_file PathBuf, mod_decl *str, curr_mod_decl *Option<[mist_parser::ast::Visibility, mist_parser::ast::Identifier]>) {
+    if let Some[[_, name]] = &curr_mod_decl {
+        if output_file.file_name().map(fn(v) -> v.to_str()).unwrap_or_default() != Some("mod.rs") {
+            if let Some[ext] = output_file.extension().map(fn(e) -> e.to_owned()) {
+                let mut new_name = std::ffi::OsString::from(&name.0);
+
+                new_name.push(".");
+                new_name.push(ext);
+
+                output_file.set_file_name(new_name);
+            } else {
+                output_file.set_file_name(&name.0);
+            }
         }
-    };
+    }
 
     let mut gc = mist_codegen::RustCodegen::new();
 
-    let parsed = match mist_parser::parse(&source) {
+    let parsed = match mist_parser::parse(source) {
         Ok[ast] => ast;
         Err[e] => {
             match e {
@@ -186,49 +234,18 @@ fn transpile_file(path *PathBuf, mut output_file PathBuf, mod_decl *str) String
         }
     };
 
-    let output = gc.generate(parsed.1);
+    let output = gc.generate(parsed);
 
-    if let [Some[[vis, name]], _] = parsed {
-        if output_file.file_name().map(fn(v) -> v.to_str()).unwrap_or_default() != Some("mod.rs") {
-            if let Some[ext] = output_file.extension().map(fn(e) -> e.to_owned()) {
-                let mut new_name = std::ffi::OsString::from(&name.0);
+    let res = fs::write(&output_file, format!("{mod_decl}{output}"));
 
-                new_name.push(".");
-                new_name.push(ext);
+    if res.is_err() {
+        eprintln!(
+            "error: failed to write output {}\n  {}",
+            output_file.display(),
+            res.unwrap_err(),
+        );
 
-                output_file.set_file_name(new_name);
-            } else {
-                output_file.set_file_name(&name.0);
-            }
-        }
-
-        let res = fs::write(&output_file, format!("{mod_decl}{output}"));
-
-        if res.is_err() {
-            eprintln!(
-                "error: failed to write output {}\n  {}",
-                output_file.display(),
-                res.unwrap_err(),
-            );
-
-            process::exit(1);
-        }
-
-        format!("{}mod {};\n", vis.get_rust(), name.get_rust())
-    } else {
-        let res = fs::write(&output_file, format!("{mod_decl}{output}"));
-
-        if res.is_err() {
-            eprintln!(
-                "error: failed to write output {}\n  {}",
-                output_file.display(),
-                res.unwrap_err(),
-            );
-
-            process::exit(1);
-        }
-
-        String::new()
+        process::exit(1);
     }
 }
 
diff --git a/crates/parser/src/grammar.pest b/crates/parser/src/grammar.pest
index a486537..aa2a8fc 100644
--- a/crates/parser/src/grammar.pest
+++ b/crates/parser/src/grammar.pest
@@ -72,6 +72,10 @@ program = {
     SOI ~ top_level* ~ EOI
 }
 
+module_program = {
+    SOI ~ top_level?
+}
+
 // ======================================================
 // MODIFIERS
 // ======================================================
diff --git a/crates/parser/src/lib.rs b/crates/parser/src/lib.rs
index 77e6bde..ea39710 100644
--- a/crates/parser/src/lib.rs
+++ b/crates/parser/src/lib.rs
@@ -14,12 +14,7 @@ use crate::error::{IntoErr, ParseError};
 #[grammar = "./src/grammar.pest"]
 pub struct MistParser;
 
-pub fn parse<'a>(
-    source: &'a str,
-) -> Result<
-    (Option<(Visibility, Identifier)>, Vec<TopLevel>),
-    ParseError<'a, (Option<(Visibility, Identifier)>, Vec<TopLevel>)>,
-> {
+pub fn parse<'a>(source: &'a str) -> Result<Vec<TopLevel>, ParseError<'a, Vec<TopLevel>>> {
     let mut pairs = MistParser::parse(Rule::program, source)?;
 
     let mut statements = vec![];
@@ -32,20 +27,10 @@ pub fn parse<'a>(
         }
     }
 
-    let m = if let Some(v) = statements.get(0) {
-        if let TopLevelKind::DeclareModule(vis, name) = &v.0.item {
-            Some((vis.clone(), name.clone()))
-        } else {
-            None
-        }
-    } else {
-        None
-    };
-
     match analyzer.build(statements) {
-        Ok(v) => Ok((m, v)),
+        Ok(v) => Ok(v),
         Err(e) => {
-            let rec = e.recovered.clone().map(move |r| (m, r));
+            let rec = e.recovered.clone();
 
             let mut e2 = e.get();
 
@@ -56,6 +41,30 @@ pub fn parse<'a>(
     }
 }
 
+pub fn parse_module<'a>(
+    source: &'a str,
+) -> Result<Option<(Visibility, Identifier)>, ParseError<'a, Option<(Visibility, Identifier)>>> {
+    let mut pairs = MistParser::parse(Rule::module_program, source)?;
+
+    if let Some(v) = pairs
+        .next()
+        .unwrap()
+        .into_inner()
+        .next()
+        .map(TopLevel::try_from)
+        .transpose()
+        .get()?
+    {
+        if let TopLevelKind::DeclareModule(vis, name) = &v.0.item {
+            Ok(Some((vis.clone(), name.clone())))
+        } else {
+            Ok(None)
+        }
+    } else {
+        Ok(None)
+    }
+}
+
 #[macro_export]
 macro_rules! ast_ensure {
     ($pair:expr, $rule:expr $(, $rules:expr)* => $body:block) => {