diff --git a/Cargo.toml b/Cargo.toml
index ab0afa3..26ce390 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,6 +3,14 @@ name = "e0"
 version = "0.1.0"
 edition = "2021"
 
+[[bin]]
+name = "e0c"
+path = "./bin/e0c.rs"
+
+[[bin]]
+name = "e0pkg"
+path = "./bin/e0pkg.rs"
+
 [dependencies]
 anyhow = "1.0.56"
 clap = { version = "3.1.8", features = ["derive"] }
diff --git a/src/main.rs b/bin/e0c.rs
similarity index 80%
rename from src/main.rs
rename to bin/e0c.rs
index 6002daf..8eeca3c 100644
--- a/src/main.rs
+++ b/bin/e0c.rs
@@ -1,23 +1,12 @@
-#[macro_use]
-extern crate lalrpop_util;
-#[macro_use]
-extern crate anyhow;
-
-lalrpop_mod!(parser);
-
-mod ast;
-pub mod codegen;
-mod utils;
-
 use std::fs::{self, File};
 use std::io::Write;
 use std::path::PathBuf;
 
 use anyhow::Result;
 use clap::Parser;
-
-use crate::codegen::{llvm_ir::LlvmIrCodegen, CodegenBackend};
-use crate::parser::ProgramParser;
+use e0::codegen::CodegenBackend;
+use e0::codegen::llvm_ir::LlvmIrCodegen;
+use e0::parser::ProgramParser;
 
 #[derive(Debug, Parser)]
 struct Opt {
@@ -40,7 +29,7 @@ fn main() -> Result<()> {
   let parser = ProgramParser::new();
   let ast = parser.parse(&contents).unwrap();
 
-  let typed_ast = ast::typed::convert(ast)?;
+  let typed_ast = e0::ast::typed::convert(ast)?;
 
   if let Some(path) = opts.emit_ast {
     let mut file = File::create(&path)?;
diff --git a/bin/e0pkg.rs b/bin/e0pkg.rs
new file mode 100644
index 0000000..65842bf
--- /dev/null
+++ b/bin/e0pkg.rs
@@ -0,0 +1,18 @@
+use clap::{Parser, Subcommand};
+
+#[derive(Debug, Parser)]
+struct Opt {
+  #[clap(subcommand)]
+  command: Command,
+}
+
+#[derive(Debug, Subcommand)]
+enum Command {
+  /// Compile an e0 package
+  #[clap(name = "build", alias = "b")]
+  Build,
+}
+
+fn main() {
+  let opts = Opt::parse();
+}
diff --git a/default.nix b/default.nix
index ccecb20..d9573d8 100644
--- a/default.nix
+++ b/default.nix
@@ -1,6 +1,6 @@
-{ fenix, makeRustPlatform, lib, nix-gitignore, libffi, libgcc }:
+{ toolchain, makeRustPlatform, lib, nix-gitignore, libffi, libgcc }:
 
-let rustPlatform = makeRustPlatform { inherit (fenix.minimal) cargo rustc; };
+let rustPlatform = makeRustPlatform { inherit (toolchain) cargo rustc; };
 
 in rustPlatform.buildRustPackage {
   name = "e0";
diff --git a/flake.nix b/flake.nix
index 81e7862..9f0e298 100644
--- a/flake.nix
+++ b/flake.nix
@@ -12,14 +12,17 @@
           inherit system;
           overlays = [ fenix.overlay ];
         };
-        myPkgs = rec { e0 = pkgs.callPackage ./. { }; };
+        toolchain = pkgs.fenix.complete;
+        myPkgs = rec { e0 = pkgs.callPackage ./. { inherit toolchain; }; };
 
       in rec {
         devShell = pkgs.mkShell {
           packages = with pkgs;
             with pkgs.llvmPackages_12; [
+              cargo-edit
               cargo-watch
               clangUseLLVM
+              (toolchain.withComponents [ "clippy" "rustc" "rust-src" ])
             ];
           inputsFrom = with myPkgs; [ e0 ];
           CARGO_UNSTABLE_SPARSE_REGISTRY = "true";
diff --git a/scripts/e0c b/scripts/e0c
deleted file mode 100755
index bbe5eab..0000000
--- a/scripts/e0c
+++ /dev/null
@@ -1,25 +0,0 @@
-#!/usr/bin/env bash
-
-set -e
-
-SOURCE=$?
-BITCODE=$(mktemp -d)
-OUTPUT=./a.out
-
-usage() { echo "$0 options:" && grep " .)\ #" $0; exit 0; }
-
-[ $# -eq 0 ] && usage
-while getopts ":hs:p:" arg; do
-  case $arg in
-    o) # Binary output
-      OUTPUT=${OPTARG}
-      ;;
-    h | *) # Display help.
-      usage
-      exit 0
-      ;;
-  esac
-done
-
-cargo run -- -o $BITCODE $SOURCE
-clang -o $OUTPUT $BITCODE
diff --git a/src/ast/cranelift.rs b/src/ast/cranelift.rs
deleted file mode 100644
index e65aa29..0000000
--- a/src/ast/cranelift.rs
+++ /dev/null
@@ -1,12 +0,0 @@
-use anyhow::Result;
-use cranelift_codegen::Context as ClifContext;
-
-use super::{Decl, Type};
-
-pub fn convert(
-  file_name: String,
-  context: &Context,
-  program: Vec<Decl<Type>>,
-) -> Result<ClifContext> {
-  todo!()
-}
diff --git a/src/ast/llvm.rs b/src/ast/llvm.rs
deleted file mode 100644
index 0b106d7..0000000
--- a/src/ast/llvm.rs
+++ /dev/null
@@ -1,349 +0,0 @@
-use std::collections::HashMap;
-
-use anyhow::Result;
-use inkwell::{
-  builder::Builder,
-  context::Context,
-  module::Module,
-  types::{BasicMetadataTypeEnum, BasicTypeEnum, FunctionType},
-  values::{BasicValue, BasicValueEnum, FunctionValue, IntValue},
-  IntPredicate,
-};
-
-use crate::utils::{
-  convert_type_to_metadata_type, convert_value_to_metadata_value,
-};
-
-use super::{Decl, ElseClause, Expr, ExprKind, IfElse, Op, Stmt, Type};
-
-impl Expr<Type> {
-  fn into_llvm<'ctx>(
-    &self,
-    context: &'ctx Context,
-    builder: &'ctx Builder,
-    env: &Env<'_, 'ctx>,
-  ) -> Result<BasicValueEnum<'ctx>> {
-    let int_ty = context.i64_type();
-    let bool_ty = context.bool_type();
-
-    match &self.kind {
-      ExprKind::Var(name) => Ok(match env.lookup(&name) {
-        Some(v) => match v.kind {
-          EnvValueKind::Local(l) => l,
-          EnvValueKind::Func(f) => {
-            let ptr = f.as_global_value().as_pointer_value();
-            builder.build_load(ptr, "")
-          }
-        },
-        None => bail!("Unbound name {name:?}"),
-      }),
-
-      ExprKind::Int(n) => {
-        Ok(BasicValueEnum::IntValue(int_ty.const_int(*n as u64, false)))
-      }
-
-      ExprKind::BinOp(left, op, right) => {
-        if !op.check_types(&left.ty, &right.ty) {
-          // TODO: detailed error message
-          bail!("Invalid types on operation.");
-        }
-
-        match op {
-          Op::Plus => {
-            let left_val =
-              left.into_llvm(context, builder, env)?.into_int_value();
-            let right_val =
-              right.into_llvm(context, builder, env)?.into_int_value();
-            let result: IntValue =
-              builder.build_int_add(left_val, right_val, "");
-            Ok(BasicValueEnum::IntValue(result))
-          }
-
-          Op::LessThan => {
-            let left_val =
-              left.into_llvm(context, builder, env)?.into_int_value();
-            let right_val =
-              right.into_llvm(context, builder, env)?.into_int_value();
-            let result: IntValue = builder.build_int_compare(
-              IntPredicate::SLT,
-              left_val,
-              right_val,
-              "",
-            );
-            Ok(BasicValueEnum::IntValue(result))
-          }
-
-          Op::GreaterThan => {
-            let left_val =
-              left.into_llvm(context, builder, env)?.into_int_value();
-            let right_val =
-              right.into_llvm(context, builder, env)?.into_int_value();
-            let result: IntValue = builder.build_int_compare(
-              IntPredicate::SGT,
-              left_val,
-              right_val,
-              "",
-            );
-            Ok(BasicValueEnum::IntValue(result))
-          }
-        }
-      }
-
-      ExprKind::Call(func, args) => match env.lookup(func) {
-        Some(EnvValue {
-          ty: func_ty,
-          kind: EnvValueKind::Func(func_ptr),
-        }) => {
-          let args_llvm = args
-            .iter()
-            .map(|arg| {
-              arg
-                .into_llvm(context, builder, env)
-                .map(convert_value_to_metadata_value)
-            })
-            .collect::<Result<Vec<_>>>()?;
-
-          let call_site =
-            builder.build_call(*func_ptr, args_llvm.as_slice(), "");
-
-          let value = call_site.try_as_basic_value().unwrap_left();
-          Ok(value)
-        }
-
-        _ => bail!("No function with name {func:?}"),
-      },
-    }
-  }
-}
-
-impl Type {
-  pub fn into_llvm_basic_type<'ctx>(
-    &self,
-    context: &'ctx Context,
-  ) -> BasicTypeEnum<'ctx> {
-    match self {
-      Type::Int => BasicTypeEnum::IntType(context.i64_type()),
-      Type::Bool => BasicTypeEnum::IntType(context.bool_type()),
-      _ => panic!("Tried to convert a function type into a LLVM basic type"),
-    }
-  }
-}
-
-fn fn_type_basic<'ctx>(
-  return_ty: BasicTypeEnum<'ctx>,
-  args: &[BasicMetadataTypeEnum<'ctx>],
-  is_var_args: bool,
-) -> FunctionType<'ctx> {
-  match return_ty {
-    BasicTypeEnum::ArrayType(ty) => ty.fn_type(args, is_var_args),
-    BasicTypeEnum::FloatType(ty) => ty.fn_type(args, is_var_args),
-    BasicTypeEnum::IntType(ty) => ty.fn_type(args, is_var_args),
-    BasicTypeEnum::PointerType(ty) => ty.fn_type(args, is_var_args),
-    BasicTypeEnum::StructType(ty) => ty.fn_type(args, is_var_args),
-    BasicTypeEnum::VectorType(ty) => ty.fn_type(args, is_var_args),
-  }
-}
-
-#[derive(Debug)]
-enum EnvValueKind<'ctx> {
-  Func(FunctionValue<'ctx>),
-  Local(BasicValueEnum<'ctx>),
-}
-
-#[derive(Debug)]
-struct EnvValue<'a, 'ctx> {
-  ty: &'a Type,
-  kind: EnvValueKind<'ctx>,
-}
-
-#[derive(Debug, Default)]
-struct Env<'a, 'ctx> {
-  parent: Option<&'a Env<'a, 'ctx>>,
-  local_type_map: HashMap<String, EnvValue<'a, 'ctx>>,
-}
-
-impl<'a, 'ctx> Env<'a, 'ctx> {
-  pub fn lookup(&self, name: impl AsRef<str>) -> Option<&EnvValue<'a, 'ctx>> {
-    match self.local_type_map.get(name.as_ref()) {
-      Some(v) => Some(v),
-      None => match &self.parent {
-        Some(p) => p.lookup(name),
-        None => None,
-      },
-    }
-  }
-}
-
-fn convert_if_else(
-  context: &Context,
-  module: &Module,
-  builder: &Builder,
-  function: &FunctionValue,
-  if_else: &IfElse<Type>,
-  env: &Env,
-) -> Result<()> {
-  let success_branch = context.append_basic_block(*function, "success");
-  let fail_branch = context.append_basic_block(*function, "fail");
-  let exit_block = context.append_basic_block(*function, "exit");
-
-  let cond = if_else
-    .cond
-    .into_llvm(context, builder, env)?
-    .into_int_value();
-  builder.build_conditional_branch(cond, success_branch, fail_branch);
-
-  // build success branch
-  builder.position_at_end(success_branch);
-  convert_stmts(context, module, function, builder, env, &if_else.body)?;
-  // builder.build_unconditional_branch(exit_branch);
-
-  // build fail branch
-  builder.position_at_end(fail_branch);
-  match &if_else.else_clause {
-    Some(ElseClause::If(if_else2)) => {
-      convert_if_else(context, module, builder, function, if_else2, env)?;
-    }
-    Some(ElseClause::Body(body)) => {
-      convert_stmts(context, module, function, builder, env, body)?;
-    }
-    None => {}
-  }
-  builder.position_at_end(fail_branch);
-  builder.build_unconditional_branch(exit_block);
-
-  builder.position_at_end(exit_block);
-
-  Ok(())
-}
-
-fn convert_stmts(
-  context: &Context,
-  module: &Module,
-  function: &FunctionValue,
-  builder: &Builder,
-  parent_env: &Env,
-  stmts: impl AsRef<[Stmt<Type>]>,
-) -> Result<()> {
-  let stmts = stmts.as_ref();
-  let mut scope_env = Env {
-    parent: Some(parent_env),
-    ..Default::default()
-  };
-
-  for stmt in stmts.iter() {
-    match stmt {
-      Stmt::Let(name, _, expr) => {
-        let ty = &expr.ty;
-        let llvm_ty = ty.into_llvm_basic_type(context);
-        // Empty variable name gets LLVM to generate a unique name
-        let alloca = builder.build_alloca(llvm_ty, "");
-
-        let expr_val = expr.into_llvm(context, builder, &scope_env)?;
-        builder.build_store(alloca, expr_val);
-
-        scope_env.local_type_map.insert(
-          name.clone(),
-          EnvValue {
-            ty,
-            kind: EnvValueKind::Local(alloca.as_basic_value_enum()),
-          },
-        );
-      }
-
-      Stmt::Return(ret_val) => {
-        if let Some(ret_val) = ret_val {
-          let value = ret_val.into_llvm(context, builder, &scope_env)?;
-          builder.build_return(Some(&value));
-        } else {
-          builder.build_return(None);
-        }
-      }
-
-      Stmt::IfElse(if_else) => {
-        convert_if_else(
-          context, module, builder, function, if_else, &scope_env,
-        )?;
-      }
-    }
-  }
-
-  Ok(())
-}
-
-pub fn convert(
-  file_name: String,
-  context: &Context,
-  program: Vec<Decl<Type>>,
-) -> Result<Module> {
-  let module = context.create_module(&file_name);
-  let builder = context.create_builder();
-
-  let mut env = Env::default();
-  for func in program.iter().filter_map(|decl| match decl {
-    Decl::Func(v) => Some(v),
-    _ => None,
-  }) {
-    let return_ty = func.return_ty.into_llvm_basic_type(context);
-    let args_ty = func
-      .args
-      .iter()
-      .map(|arg| {
-        convert_type_to_metadata_type(arg.ty.into_llvm_basic_type(context))
-      })
-      .collect::<Vec<_>>();
-    let llvm_func_ty = fn_type_basic(return_ty, &args_ty, false);
-    let llvm_func = module.add_function(&func.name, llvm_func_ty, None);
-
-    env.local_type_map.insert(
-      func.name.clone(),
-      EnvValue {
-        ty: &func.ty,
-        kind: EnvValueKind::Func(llvm_func),
-      },
-    );
-  }
-
-  for func in program.iter().filter_map(|decl| match decl {
-    Decl::Func(v) => Some(v),
-    _ => None,
-  }) {
-    let llvm_func = match env.local_type_map.get(&func.name) {
-      Some(EnvValue {
-        kind: EnvValueKind::Func(func),
-        ..
-      }) => func.clone(),
-      _ => unreachable!(),
-    };
-
-    let entry_block = context.append_basic_block(llvm_func, "entry");
-
-    builder.position_at_end(entry_block);
-
-    let mut scoped_env = Env {
-      parent: Some(&env),
-      local_type_map: HashMap::new(),
-    };
-
-    for (arg, param) in func.args.iter().zip(llvm_func.get_params().into_iter())
-    {
-      scoped_env.local_type_map.insert(
-        arg.name.clone(),
-        EnvValue {
-          ty: &arg.ty,
-          kind: EnvValueKind::Local(param),
-        },
-      );
-    }
-
-    convert_stmts(
-      &context,
-      &module,
-      &llvm_func,
-      &builder,
-      &scoped_env,
-      &func.stmts,
-    )?;
-  }
-
-  Ok(module)
-}
diff --git a/src/ast/mod.rs b/src/ast/mod.rs
index 9f9f4d4..3eb75f9 100644
--- a/src/ast/mod.rs
+++ b/src/ast/mod.rs
@@ -1,5 +1,3 @@
-// pub mod llvm;
-// pub mod cranelift;
 pub mod typed;
 
 #[derive(Debug)]
@@ -64,9 +62,11 @@ pub enum Op {
 }
 
 impl Op {
+  /// Check that the types match the current operation. If so, return the type
+  /// that is expected as a result. Otherwise, return None.
   pub fn check_types(&self, left_ty: &Type, right_ty: &Type) -> Option<Type> {
-    // TODO: since only binops work on integers right now, just check that the two sides are both
-    // integers. this will have to change once && gets added.
+    // TODO: since only binops work on integers right now, just check that the
+    // two sides are both integers. this will have to change once && gets added.
     match (left_ty, right_ty) {
       (Type::Int, Type::Int) => Some(Type::Int),
       _ => None,
diff --git a/src/codegen/llvm_ir/if_else.rs b/src/codegen/llvm_ir/if_else.rs
index 4599703..1cf8338 100644
--- a/src/codegen/llvm_ir/if_else.rs
+++ b/src/codegen/llvm_ir/if_else.rs
@@ -2,7 +2,7 @@ use std::io::Write;
 
 use anyhow::Result;
 
-use crate::ast::{ElseClause, IfElse, Stmt, Type};
+use crate::ast::{ElseClause, IfElse, Type};
 
 use super::LlvmIrCodegen;
 
diff --git a/src/lib.rs b/src/lib.rs
new file mode 100644
index 0000000..bbc6c3f
--- /dev/null
+++ b/src/lib.rs
@@ -0,0 +1,10 @@
+#[macro_use]
+extern crate lalrpop_util;
+#[macro_use]
+extern crate anyhow;
+
+lalrpop_mod!(pub parser);
+
+pub mod ast;
+pub mod codegen;
+mod utils;
diff --git a/std/e0pkg.yml b/std/e0pkg.yml
new file mode 100644
index 0000000..990b48b
--- /dev/null
+++ b/std/e0pkg.yml
@@ -0,0 +1,4 @@
+name: std
+version: 0.1.0
+authors:
+  - Michael Zhang <mail@mzhang.io>