diff --git a/programs/aidl/Cargo.toml b/programs/aidl/Cargo.toml
index 7616c2c..75503f4 100644
--- a/programs/aidl/Cargo.toml
+++ b/programs/aidl/Cargo.toml
@@ -7,5 +7,9 @@ edition = "2021"
 
 [dependencies]
 codespan-reporting = "0.11.1"
+derive_more = "0.99.17"
 logos = "0"
+proc-macro2 = "1.0.56"
+quote = "1.0.26"
+syn = "2.0.15"
 thiserror = "1"
diff --git a/programs/aidl/assets/core.idl b/programs/aidl/assets/core.idl
index 1067197..330598f 100644
--- a/programs/aidl/assets/core.idl
+++ b/programs/aidl/assets/core.idl
@@ -15,7 +15,7 @@ Enumeration Option<T> {
 }
 
 Structure Version {
-    major: Byte,
-    minor: Byte,
-    patch: Byte,
+  major: Byte,
+  minor: Byte,
+  patch: Byte,
 }
diff --git a/programs/aidl/assets/error_example.idl b/programs/aidl/assets/error_example.idl
new file mode 100644
index 0000000..6fbd52c
--- /dev/null
+++ b/programs/aidl/assets/error_example.idl
@@ -0,0 +1,19 @@
+Type UUID = Array<U8, 16>;
+
+Type Nanoseconds = U32;
+
+Structure Duration {
+  secs: U64
+  nanos: Nanoseconds
+}
+
+Structure LinkedList<T> {
+  data: T,
+  child: Option<LinkedList<T>>,
+}
+
+Constant VERSION = Version {
+  major: 1,
+  minor: 0,
+  patch: 0
+};
diff --git a/programs/aidl/assets/examples.idl b/programs/aidl/assets/examples.idl
deleted file mode 100644
index b4070ea..0000000
--- a/programs/aidl/assets/examples.idl
+++ /dev/null
@@ -1,13 +0,0 @@
-Type UUID = Array[U8; 16];
-
-Type Nanoseconds = U32;
-
-Structure Duration{
-    secs: U64,
-    nanos: Nanoseconds,
-}
-
-Structure LinkedList{
-    data: Any,
-    child: Option<LinkedList>,
-}
\ No newline at end of file
diff --git a/programs/aidl/assets/vfs.idl b/programs/aidl/assets/vfs.idl
index c9131ad..10d0a51 100644
--- a/programs/aidl/assets/vfs.idl
+++ b/programs/aidl/assets/vfs.idl
@@ -1,11 +1,11 @@
 // core provides lots of useful types like String and Byte
 Use core;
 
-Constant VERSION = Version {
+Constant VERSION = Make Version {
     major: 1,
     minor: 0,
     patch: 0,
-}
+};
 
 Alias Path = String;
 
@@ -15,10 +15,10 @@ Structure File {
 }
 
 Interface File {
-    function new accepts(Path) returns(None);
+    Function new Takes(Path) Returns(None);
 
     // Open in this iteration assumes the file exists
-    function open accepts(Path) returns(File);
+    Function open Takes(Path) Returns(File);
 
-    function close accepts(File) returns(None);
+    Function close Takes(File) Returns(None);
 }
diff --git a/programs/aidl/src/ast.rs b/programs/aidl/src/ast.rs
index 78b7ee3..3ffa60d 100644
--- a/programs/aidl/src/ast.rs
+++ b/programs/aidl/src/ast.rs
@@ -22,7 +22,7 @@ pub enum Item {
     Constant(ItemConstant),
     Function(Function),
     Structure(ItemStructure),
-    Enumeration(ItemEnumeration)
+    Enumeration(ItemEnumeration),
 }
 
 #[derive(Debug, Default)]
@@ -42,7 +42,7 @@ impl Type {
     pub fn infer() -> Self {
         Self {
             name: String::from(INFER_TYPE),
-            arguments: TypeArguments::None
+            arguments: TypeArguments::None,
         }
     }
 }
@@ -82,6 +82,7 @@ pub struct ItemInterface {
 pub struct ItemStructure {
     pub name: String,
     pub fields: HashMap<String, Type>,
+    pub arguments: TypeArguments,
 }
 
 #[derive(Debug)]
@@ -100,13 +101,13 @@ pub struct ItemConstant {
 pub struct ItemEnumeration {
     pub name: String,
     pub arguments: TypeArguments,
-    pub variants: Vec<EnumerationVariant>
+    pub variants: Vec<EnumerationVariant>,
 }
 
 #[derive(Debug)]
 pub struct EnumerationVariant {
     pub name: String,
-    pub content: EnumerationContent
+    pub content: EnumerationContent,
 }
 
 #[derive(Debug, Default)]
@@ -115,7 +116,7 @@ pub enum EnumerationContent {
     None,
     Tuple(Vec<Type>),
     Structure(HashMap<String, Type>),
-    Value(NumberLiteral)
+    Value(NumberLiteral),
 }
 
 #[derive(Debug)]
@@ -143,22 +144,32 @@ pub enum Literal {
     Char(char),
 }
 
-#[derive(Debug)]
+#[derive(Debug, derive_more::Display)]
 pub enum NumberLiteral {
+    #[display(fmt = "{_0}ptr")]
     Ptr(usize),
 
+    #[display(fmt = "{_0}u8")]
     U8(u8),
+    #[display(fmt = "{_0}i8")]
     I8(i8),
 
+    #[display(fmt = "{_0}u16")]
     U16(u16),
+    #[display(fmt = "{_0}i16")]
     I16(i16),
 
+    #[display(fmt = "{_0}u32")]
     U32(u32),
+    #[display(fmt = "{_0}i32")]
     I32(i32),
 
+    #[display(fmt = "{_0}u64")]
     U64(u64),
+    #[display(fmt = "{_0}i64")]
     I64(i64),
 
+    #[display(fmt = "{_0}")]
     Infer(i64),
 }
 
diff --git a/programs/aidl/src/codegen.rs b/programs/aidl/src/codegen.rs
new file mode 100644
index 0000000..6baf426
--- /dev/null
+++ b/programs/aidl/src/codegen.rs
@@ -0,0 +1,10 @@
+use std::path::Path;
+
+use crate::ast::IDLModule;
+
+use proc_macro2::{TokenStream, Ident, Span};
+use quote::quote;
+
+pub fn generate(module: IDLModule) -> TokenStream {
+    quote! {}
+}
diff --git a/programs/aidl/src/lexer.rs b/programs/aidl/src/lexer.rs
index 0e11bd6..1fa8e9e 100644
--- a/programs/aidl/src/lexer.rs
+++ b/programs/aidl/src/lexer.rs
@@ -5,119 +5,175 @@ use std::{
 
 use logos::Logos;
 
-#[derive(Logos, Debug, PartialEq)]
+#[derive(Logos, Debug, PartialEq, derive_more::Display, Clone)]
 #[logos(skip r"[ \t\n\f]+")]
 pub enum Token {
     #[token("{")]
+    #[display(fmt = "{{")]
     LeftCurly,
 
     #[token("}")]
+    #[display(fmt = "}}")]
     RightCurly,
 
     #[token("(")]
+    #[display(fmt = "(")]
     LeftParen,
 
     #[token(")")]
+    #[display(fmt = ")")]
     RightParen,
 
     #[token(";")]
+    #[display(fmt = ";")]
     Semicolon,
 
     #[token(":")]
+    #[display(fmt = ":")]
     Colon,
 
     #[token("<")]
+    #[display(fmt = "<")]
     LeftArrow,
 
     #[token(">")]
+    #[display(fmt = ">")]
     RightArrow,
 
     #[token(",")]
+    #[display(fmt = ",")]
     Comma,
 
     #[token("=")]
+    #[display(fmt = "=")]
     Equals,
 
     #[token(".")]
+    #[display(fmt = ".")]
     Dot,
 
     // why
     #[regex("\"(?s:[^\"\\\\]|\\\\.)*\"", |lex| lex.slice().strip_prefix('"')?.strip_suffix('"').map(ToOwned::to_owned))]
+    #[display(fmt = "\"{_0}\"")]
     StringLiteral(String),
 
     #[regex(r"'.'", |lex| lex.slice().strip_prefix('\'')?.strip_suffix('\'')?.parse().ok())]
+    #[display(fmt = "{_0}")]
     CharLiteral(char),
 
     #[regex(r#"(-)?\d+"#, |lex| lex.slice().parse().ok())]
+    #[display(fmt = "{_0}")]
     NumberLiteral(i64),
 
     #[regex(
-        r"(ptr|u8|i8|u16|i16|u32|i32|u64|i64|f32|f64)",
+        "(ptr|u8|i8|u16|i16|u32|i32|u64|i64|f32|f64)",
         |lex| NumberSuffix::lexer(lex.slice()).next().and_then(Result::ok)
     )]
+    #[display(fmt = "{_0}")]
     NumberSuffix(NumberSuffix),
 
     #[regex(r#"[a-zA-Z_][a-zA-Z\d_]*"#, |lex| Ident::lexer(lex.slice()).next().and_then(Result::ok))]
+    #[display(fmt = "{_0}")]
     Ident(Ident),
 
     #[regex(r"//.*", |lex| lex.slice().parse().ok())]
+    #[display(fmt = "//{_0}")]
     Comment(String),
 }
 
-#[derive(Logos, Debug, PartialEq, Eq)]
+#[derive(Logos, Debug, Clone, PartialEq, Eq, derive_more::Display)]
 pub enum Ident {
     #[token("Interface")]
+    #[display(fmt = "Interface")]
     Interface,
     #[token("Function")]
+    #[display(fmt = "Function")]
     Function,
     #[token("Constant")]
+    #[display(fmt = "Constant")]
     Constant,
     #[token("Structure")]
+    #[display(fmt = "Structure")]
     Structure,
     #[token("Alias")]
+    #[display(fmt = "Alias")]
     Alias,
     #[token("Enumeration")]
+    #[display(fmt = "Enumeration")]
     Enumeration,
     #[token("Use")]
+    #[display(fmt = "Use")]
     Use,
     #[token("Make")]
+    #[display(fmt = "Make")]
     Make,
     #[token("Takes")]
+    #[display(fmt = "Takes")]
     Takes,
     #[token("Returns")]
+    #[display(fmt = "Returns")]
     Returns,
     #[token("_")]
+    #[display(fmt = "_")]
     Underscore,
     #[regex(r"[a-zA-Z_][a-zA-Z\d_]*", |lex| lex.slice().parse().ok())]
+    #[display(fmt = "{_0}")]
     Other(String),
 }
 
-#[derive(Logos, Debug, PartialEq, Eq)]
+#[derive(Logos, Debug, Clone, Copy, PartialEq, Eq, derive_more::Display)]
 pub enum NumberSuffix {
-    #[token("Ptr")]
+    #[token("ptr")]
+    #[display(fmt = "ptr")]
     Ptr,
     #[token("u8")]
+    #[display(fmt = "u8")]
     U8,
     #[token("i8")]
+    #[display(fmt = "i8")]
     I8,
     #[token("u16")]
+    #[display(fmt = "u16")]
     U16,
     #[token("i16")]
+    #[display(fmt = "i16")]
     I16,
     #[token("u32")]
+    #[display(fmt = "u32")]
     U32,
     #[token("i32")]
+    #[display(fmt = "i32")]
     I32,
     #[token("u64")]
+    #[display(fmt = "u64")]
     U64,
     #[token("i64")]
+    #[display(fmt = "i64")]
     I64,
     #[token("f32")]
+    #[display(fmt = "f32")]
     F32,
     #[token("f64")]
+    #[display(fmt = "f64")]
     F64,
 }
 
+impl NumberSuffix {
+    pub const ALL_SUFFIXES: [&str; 11] = [
+        "ptr",
+        "u8",
+        "i8",
+        "u16",
+        "i16",
+        "u32",
+        "i32",
+        "u64",
+        "i64",
+        "f32",
+        "f64"
+    ];
+}
+
 #[derive(Debug, Clone)]
 pub struct Span(pub Range<usize>);
 impl Span {
diff --git a/programs/aidl/src/main.rs b/programs/aidl/src/main.rs
index 62527ba..10301d4 100644
--- a/programs/aidl/src/main.rs
+++ b/programs/aidl/src/main.rs
@@ -1,12 +1,20 @@
 #![feature(result_option_inspect)]
 #![allow(non_snake_case)]
 
-use std::path::Path;
+use std::{fmt::Display, path::Path, process::exit};
 
 use codespan_reporting::{
-    diagnostic::Label,
-    term::{termcolor::StandardStream, Config},
+    diagnostic::{Diagnostic, Label, Severity},
+    files::SimpleFile,
+    term::{
+        emit,
+        termcolor::{ColorSpec, StandardStream, StandardStreamLock},
+        Config, Styles,
+    },
 };
+use lexer::{NumberSuffix, Token};
+use logos::Logos;
+use parser::TokenIterator;
 
 use crate::lexer::Spanned;
 
@@ -16,20 +24,95 @@ mod parser;
 
 //const TEST: &str = include_str!("../assets/why.idl");
 
+fn precheck<N: Display + Clone, S: AsRef<str>>(
+    writer: &mut StandardStreamLock<'_>,
+    config: &Config,
+    file: &SimpleFile<N, S>,
+) {
+    let mut lexer = TokenIterator::new(file.source().as_ref());
+    let mut diagnostics = vec![];
+    let mut previous = lexer.peek().ok().map(|Spanned(a, b)| Spanned(a.clone(), b));
+
+    while let Ok(Spanned(token, span)) = lexer.next() {
+        let prev = Spanned(token.clone(), span.clone());
+        match token {
+            Token::Ident(lexer::Ident::Other(t)) if t == "Type" => {
+                diagnostics.push(
+                    Diagnostic::error()
+                        .with_labels(vec![Label::primary((), span.0)])
+                        .with_message("`Type` is not supported anymore.")
+                        .with_notes(vec!["use `Alias` instead of `Type`".into()]),
+                );
+            }
+            Token::Ident(lexer::Ident::Other(ident))
+                if lexer
+                    .peek()
+                    .is_ok_and(|Spanned(a, _)| matches!(a, Token::LeftCurly))
+                    && previous.is_some_and(|Spanned(ref a, _)| matches!(a, Token::Equals)) =>
+            {
+                diagnostics.push(
+                    Diagnostic::error()
+                        .with_message("Unknown expression")
+                        .with_labels(vec![Label::primary((), span.0.clone())])
+                        .with_notes(vec![
+                            format!("add `Make` before the structure name to create a Make expression that will construct the `{ident}` structure"
+                                ),
+                        ]),
+                );
+            }
+            Token::Ident(lexer::Ident::Other(ident))
+                if NumberSuffix::ALL_SUFFIXES.contains(&ident.to_lowercase().as_str()) =>
+            {
+                diagnostics.push(
+                    Diagnostic::warning()
+                        .with_message("Potentially invalid use of an uppercased number type")
+                        .with_labels(vec![Label::primary((), span.0)])
+                        .with_notes(vec![format!(
+                            "Replace {ident} with {}",
+                            ident.to_lowercase()
+                        ), "Code generation might fail".into()]),
+                );
+            }
+            _ => {}
+        }
+        previous = Some(prev);
+    }
+
+    if !diagnostics.is_empty() {
+        let mut was_fatal = false;
+        for diagnostic in diagnostics {
+            if let Severity::Error | Severity::Bug = &diagnostic.severity {
+                was_fatal = true;
+            }
+
+            emit(writer, config, file, &diagnostic).unwrap();
+        }
+
+        if was_fatal {
+            exit(1);
+        }
+    }
+}
+
 fn main() {
     let mut args = std::env::args();
     args.next().unwrap();
     if let Some(file) = args.next() {
         let path = Path::new(&file);
-        dbg!(path);
         let codespan_file = codespan_reporting::files::SimpleFile::new(
             &file,
             std::fs::read_to_string(path).unwrap(),
         );
         let writer = StandardStream::stdout(codespan_reporting::term::termcolor::ColorChoice::Auto);
-        let config = Config::default();
+        let config = Config {
+            tab_width: 2,
+            ..Default::default()
+        };
+
+        precheck(&mut writer.lock(), &config, &codespan_file);
+
         match parser::parse(codespan_file.source()) {
-            Ok(ast) => println!("SUCCESS: \n{:#?}", ast),
+            Ok(ast) => println!("{:#?}", ast),
             Err(e) => {
                 let msg = e.to_string();
                 let label = match e {
diff --git a/programs/aidl/src/parser/mod.rs b/programs/aidl/src/parser/mod.rs
index b443b6b..a1f0b0a 100644
--- a/programs/aidl/src/parser/mod.rs
+++ b/programs/aidl/src/parser/mod.rs
@@ -12,7 +12,7 @@ use crate::{
 };
 use std::iter::Iterator;
 
-struct TokenIterator<'a> {
+pub struct TokenIterator<'a> {
     lexer: Lexer<'a, Token>,
     peeked: Option<Option<Token>>,
 }
@@ -102,11 +102,17 @@ impl<'a> Parser<'a> {
     fn ask_ident(&mut self) -> Result<Spanned<String>, ParserError> {
         Ok(
             match self.get_real(
-                |token| matches!(token, Token::Ident(Ident::Other(_) | Ident::Underscore)),
+                |token| {
+                    matches!(
+                        token,
+                        Token::Ident(Ident::Other(_) | Ident::Underscore) | Token::NumberSuffix(_)
+                    )
+                },
                 "an identifier",
             )? {
                 Spanned(Token::Ident(Ident::Other(ident)), span) => Spanned(ident, span),
                 Spanned(Token::Ident(Ident::Underscore), span) => Spanned("_".to_owned(), span),
+                Spanned(Token::NumberSuffix(suffix), span) => Spanned(suffix.to_string(), span),
                 _ => unreachable!(),
             },
         )
diff --git a/programs/aidl/src/parser/structure.rs b/programs/aidl/src/parser/structure.rs
index 32db118..14a82fa 100644
--- a/programs/aidl/src/parser/structure.rs
+++ b/programs/aidl/src/parser/structure.rs
@@ -1,6 +1,9 @@
 use std::collections::HashMap;
 
-use crate::{lexer::{Ident, Spanned, Token}, ast::{Type, ItemStructure}};
+use crate::{
+    ast::{ItemStructure, Type},
+    lexer::{Ident, Spanned, Token},
+};
 
 use super::{Parser, ParserError};
 
@@ -11,7 +14,7 @@ impl<'a> Parser<'a> {
             "the `Structure` keyword",
         )?;
 
-        let Spanned(name, _) = self.ask_ident()?;
+        let Spanned(Type { name, arguments }, _) = self.ask_type()?;
         let Spanned(_, _) = self.get_real(
             |token| matches!(token, Token::LeftCurly),
             "an opening curly brace (`{`)",
@@ -36,7 +39,14 @@ impl<'a> Parser<'a> {
         }
 
         if let Spanned(Token::RightCurly, end) = self.tokens.next()? {
-            return Ok(Spanned(ItemStructure { name, fields }, span + end));
+            return Ok(Spanned(
+                ItemStructure {
+                    name,
+                    fields,
+                    arguments,
+                },
+                span + end,
+            ));
         };
 
         Err(self.expected("closing curly braces"))
diff --git a/programs/aidl/src/parser/types.rs b/programs/aidl/src/parser/types.rs
index 27180c0..5afbefa 100644
--- a/programs/aidl/src/parser/types.rs
+++ b/programs/aidl/src/parser/types.rs
@@ -7,6 +7,17 @@ use super::{Parser, ParserError};
 
 impl<'a> Parser<'a> {
     pub fn ask_type(&mut self) -> Result<Spanned<Type>, ParserError> {
+        if let Spanned(Token::NumberLiteral(_), _) = self.tokens.peek()? {
+            let Spanned(number, span) = self._ask_number_literal()?;
+            return Ok(Spanned(
+                Type {
+                    name: number.to_string(),
+                    arguments: TypeArguments::None,
+                },
+                span,
+            ));
+        };
+
         let Spanned(name, span) = self.ask_ident()?;
 
         if name == INFER_TYPE {
@@ -28,7 +39,9 @@ impl<'a> Parser<'a> {
 
             loop {
                 match self.tokens.peek()? {
-                    Spanned(Token::Ident(_), _) => args.push(Box::new(self.ask_type()?.0)),
+                    Spanned(Token::Ident(_) | Token::NumberLiteral(_), _) => {
+                        args.push(Box::new(self.ask_type()?.0))
+                    }
                     Spanned(Token::RightArrow, _) => {
                         self.eat();
                         break;