diff --git a/cli/src/main.rs b/cli/src/main.rs
index 0be3741de3..239f10a31b 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -16,7 +16,7 @@ use roc_gen::llvm::build::{
 use roc_gen::llvm::convert::basic_type_from_layout;
 use roc_load::file::{LoadedModule, LoadingProblem};
 use roc_module::symbol::Symbol;
-use roc_mono::expr::{Expr, Procs};
+use roc_mono::expr::{Env, Expr, PartialProc, Procs};
 use roc_mono::layout::Layout;
 use std::time::SystemTime;
 
@@ -220,6 +220,8 @@ async fn build_file(
     Ok(binary_path)
 }
 
+// TODO this should probably use more helper functions
+#[allow(clippy::cognitive_complexity)]
 fn gen(
     arena: &Bump,
     loaded: LoadedModule,
@@ -275,17 +277,22 @@ fn gen(
         }
     }
 
+    let mut decls_by_id = loaded.declarations_by_id;
+    let home_decls = decls_by_id
+        .remove(&loaded.module_id)
+        .expect("Root module ID not found in loaded declarations_by_id");
+
     // We use a loop label here so we can break all the way out of a nested
     // loop inside DeclareRec if we find the expr there.
     //
     // https://doc.rust-lang.org/1.30.0/book/first-edition/loops.html#loop-labels
-    'find_expr: for decl in loaded.declarations {
+    'find_expr: for decl in home_decls.iter() {
         use roc_can::def::Declaration::*;
 
         match decl {
             Declare(def) => {
                 if def.pattern_vars.contains_key(&main_symbol) {
-                    main_expr = Some(def.loc_expr);
+                    main_expr = Some(def.loc_expr.clone());
 
                     break 'find_expr;
                 }
@@ -294,7 +301,7 @@ fn gen(
             DeclareRec(defs) => {
                 for def in defs {
                     if def.pattern_vars.contains_key(&main_symbol) {
-                        main_expr = Some(def.loc_expr);
+                        main_expr = Some(def.loc_expr.clone());
 
                         break 'find_expr;
                     }
@@ -347,20 +354,74 @@ fn gen(
         ptr_bytes,
     };
     let mut procs = Procs::default();
-    let mut ident_ids = env.interns.all_ident_ids.remove(&home).unwrap();
-
-    // Populate Procs and get the low-level Expr from the canonical Expr
     let mut mono_problems = std::vec::Vec::new();
-    let main_body = Expr::new(
-        &arena,
-        &mut subs,
-        &mut mono_problems,
-        loc_expr.value,
-        &mut procs,
+    let mut ident_ids = env.interns.all_ident_ids.remove(&home).unwrap();
+    let mut mono_env = Env {
+        arena,
+        subs: &mut subs,
+        problems: &mut mono_problems,
         home,
-        &mut ident_ids,
-        ptr_bytes,
-    );
+        ident_ids: &mut ident_ids,
+        pointer_size: ptr_bytes,
+        symbol_counter: 0,
+        jump_counter: arena.alloc(0),
+    };
+
+    // Add modules' decls to Procs
+    for (_, mut decls) in decls_by_id
+        .drain()
+        .chain(std::iter::once((loaded.module_id, home_decls)))
+    {
+        for decl in decls.drain(..) {
+            use roc_can::def::Declaration::*;
+            use roc_can::expr::Expr::*;
+            use roc_can::pattern::Pattern::*;
+
+            match decl {
+                Declare(def) => match def.loc_pattern.value {
+                    Identifier(symbol) => {
+                        match def.loc_expr.value {
+                            Closure(annotation, _, _, loc_args, boxed_body) => {
+                                let (loc_body, ret_var) = *boxed_body;
+
+                                procs.insert_closure(
+                                    &mut mono_env,
+                                    Some(symbol),
+                                    annotation,
+                                    loc_args,
+                                    loc_body,
+                                    ret_var,
+                                );
+                            }
+                            body => {
+                                let proc = PartialProc {
+                                    annotation: def.expr_var,
+                                    // This is a 0-arity thunk, so it has no arguments.
+                                    patterns: bumpalo::collections::Vec::new_in(arena),
+                                    body,
+                                };
+
+                                procs.user_defined.insert(symbol, proc);
+                                procs.module_thunks.insert(symbol);
+                            }
+                        };
+                    }
+                    other => {
+                        todo!("TODO gracefully handle Declare({:?})", other);
+                    }
+                },
+                DeclareRec(_defs) => {
+                    todo!("TODO support DeclareRec");
+                }
+                InvalidCycle(_loc_idents, _regions) => {
+                    todo!("TODO handle InvalidCycle");
+                }
+            }
+        }
+    }
+
+    // Populate Procs further and get the low-level Expr from the canonical Expr
+    let main_body = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
     // Put this module's ident_ids back in the interns, so we can use them in env.
     env.interns.all_ident_ids.insert(home, ident_ids);
diff --git a/cli/src/repl.rs b/cli/src/repl.rs
index ce6df93395..6f3c072b49 100644
--- a/cli/src/repl.rs
+++ b/cli/src/repl.rs
@@ -246,16 +246,17 @@ pub fn gen(src: &str, target: Triple, opt_level: OptLevel) -> Result<(String, St
 
     // Populate Procs and get the low-level Expr from the canonical Expr
     let mut mono_problems = Vec::new();
-    let main_body = roc_mono::expr::Expr::new(
-        &arena,
-        &mut subs,
-        &mut mono_problems,
-        loc_expr.value,
-        &mut procs,
+    let mut mono_env = roc_mono::expr::Env {
+        arena: &arena,
+        subs: &mut subs,
+        problems: &mut mono_problems,
         home,
-        &mut ident_ids,
-        ptr_bytes,
-    );
+        ident_ids: &mut ident_ids,
+        pointer_size: ptr_bytes,
+        symbol_counter: 0,
+        jump_counter: arena.alloc(0),
+    };
+    let main_body = roc_mono::expr::Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
     // Put this module's ident_ids back in the interns, so we can use them in Env.
     env.interns.all_ident_ids.insert(home, ident_ids);
diff --git a/compiler/builtins/src/std.rs b/compiler/builtins/src/std.rs
index 09a51ce1b7..55ed8dc92f 100644
--- a/compiler/builtins/src/std.rs
+++ b/compiler/builtins/src/std.rs
@@ -35,8 +35,7 @@ pub fn standard_stdlib() -> StdLib {
     }
 }
 
-/// Keep this up to date by hand!
-///
+/// Keep this up to date by hand! It's the number of builtin aliases that are imported by default.
 const NUM_BUILTIN_IMPORTS: usize = 7;
 
 /// These can be shared between definitions, they will get instantiated when converted to Type
diff --git a/compiler/can/src/builtins.rs b/compiler/can/src/builtins.rs
index 00d7266c9e..85929ff2b8 100644
--- a/compiler/can/src/builtins.rs
+++ b/compiler/can/src/builtins.rs
@@ -3,8 +3,8 @@ use crate::expr::Expr;
 use crate::expr::Recursive;
 use roc_collections::all::SendMap;
 use roc_module::ident::TagName;
+use roc_module::operator::CalledVia;
 use roc_module::symbol::Symbol;
-use roc_parse::operator::CalledVia;
 use roc_region::all::{Located, Region};
 use roc_types::subs::{VarStore, Variable};
 
diff --git a/compiler/can/src/expr.rs b/compiler/can/src/expr.rs
index 1289a61730..22d627824d 100644
--- a/compiler/can/src/expr.rs
+++ b/compiler/can/src/expr.rs
@@ -10,9 +10,9 @@ use crate::procedure::References;
 use crate::scope::Scope;
 use roc_collections::all::{ImSet, MutMap, MutSet, SendMap};
 use roc_module::ident::{Lowercase, TagName};
+use roc_module::operator::CalledVia;
 use roc_module::symbol::Symbol;
 use roc_parse::ast;
-use roc_parse::operator::CalledVia;
 use roc_parse::pattern::PatternType::*;
 use roc_problem::can::{PrecedenceProblem, Problem, RuntimeError};
 use roc_region::all::{Located, Region};
diff --git a/compiler/can/src/operator.rs b/compiler/can/src/operator.rs
index 297b3d4bcf..6e005d9396 100644
--- a/compiler/can/src/operator.rs
+++ b/compiler/can/src/operator.rs
@@ -1,10 +1,10 @@
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
 use roc_module::ident::ModuleName;
+use roc_module::operator::BinOp::Pizza;
+use roc_module::operator::{BinOp, CalledVia};
 use roc_parse::ast::Expr::{self, *};
 use roc_parse::ast::{AssignedField, Def, Pattern, WhenBranch};
-use roc_parse::operator::BinOp::Pizza;
-use roc_parse::operator::{BinOp, CalledVia};
 use roc_region::all::{Located, Region};
 
 // BinOp precedence logic adapted from Gluon by Markus Westerlind, MIT licensed
@@ -201,7 +201,7 @@ pub fn desugar_expr<'a>(arena: &'a Bump, loc_expr: &'a Located<Expr<'a>>) -> &'a
             })
         }
         UnaryOp(loc_arg, loc_op) | Nested(UnaryOp(loc_arg, loc_op)) => {
-            use roc_parse::operator::UnaryOp::*;
+            use roc_module::operator::UnaryOp::*;
 
             let region = loc_op.region;
             let op = loc_op.value;
@@ -327,7 +327,7 @@ fn binop_to_function(binop: BinOp) -> (&'static str, &'static str) {
 }
 
 fn desugar_bin_op<'a>(arena: &'a Bump, loc_expr: &'a Located<Expr<'_>>) -> &'a Located<Expr<'a>> {
-    use roc_parse::operator::Associativity::*;
+    use roc_module::operator::Associativity::*;
     use std::cmp::Ordering;
 
     let mut infixes = Infixes::new(loc_expr);
diff --git a/compiler/fmt/src/expr.rs b/compiler/fmt/src/expr.rs
index a25a394d7b..74faab0577 100644
--- a/compiler/fmt/src/expr.rs
+++ b/compiler/fmt/src/expr.rs
@@ -4,9 +4,8 @@ use crate::spaces::{
     add_spaces, fmt_comments_only, fmt_condition_spaces, fmt_spaces, is_comment, newline, INDENT,
 };
 use bumpalo::collections::{String, Vec};
+use roc_module::operator::{self, BinOp};
 use roc_parse::ast::{AssignedField, Base, CommentOrNewline, Expr, Pattern, WhenBranch};
-use roc_parse::operator;
-use roc_parse::operator::BinOp;
 use roc_region::all::Located;
 
 pub fn fmt_expr<'a>(
diff --git a/compiler/gen/tests/helpers/eval.rs b/compiler/gen/tests/helpers/eval.rs
index 34f9dd5b44..69208d006c 100644
--- a/compiler/gen/tests/helpers/eval.rs
+++ b/compiler/gen/tests/helpers/eval.rs
@@ -63,7 +63,17 @@ macro_rules! assert_llvm_evals_to {
 
         // Populate Procs and get the low-level Expr from the canonical Expr
         let mut mono_problems = Vec::new();
-        let main_body = Expr::new(&arena, &mut subs, &mut mono_problems, loc_expr.value, &mut procs, home, &mut ident_ids, ptr_bytes);
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
+            home,
+            ident_ids: &mut ident_ids,
+            pointer_size: ptr_bytes,
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let main_body = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         // Put this module's ident_ids back in the interns, so we can use them in Env.
         env.interns.all_ident_ids.insert(home, ident_ids);
@@ -215,7 +225,17 @@ macro_rules! assert_opt_evals_to {
 
         // Populate Procs and get the low-level Expr from the canonical Expr
         let mut mono_problems = Vec::new();
-        let main_body = Expr::new(&arena, &mut subs, &mut mono_problems, loc_expr.value, &mut procs, home, &mut ident_ids, ptr_bytes);
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
+            home,
+            ident_ids: &mut ident_ids,
+            pointer_size: ptr_bytes,
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let main_body = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         // Put this module's ident_ids back in the interns, so we can use them in Env.
         env.interns.all_ident_ids.insert(home, ident_ids);
@@ -361,7 +381,17 @@ macro_rules! emit_expr {
         let mut ident_ids = env.interns.all_ident_ids.remove(&home).unwrap();
 
         // Populate Procs and get the low-level Expr from the canonical Expr
-        let main_body = Expr::new(&arena, &mut subs, loc_expr.value, &mut procs, home, &mut ident_ids, $crate::helpers::eval::POINTER_SIZE);
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
+            home,
+            ident_ids: &mut ident_ids,
+            pointer_size: ptr_bytes,
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let main_body = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         // Put this module's ident_ids back in the interns, so we can use them in Env.
         env.interns.all_ident_ids.insert(home, ident_ids);
diff --git a/compiler/gen/tests/helpers/mod.rs b/compiler/gen/tests/helpers/mod.rs
index b3bfae3e2c..60f955af4a 100644
--- a/compiler/gen/tests/helpers/mod.rs
+++ b/compiler/gen/tests/helpers/mod.rs
@@ -282,7 +282,7 @@ pub fn can_expr_with(arena: &Bump, home: ModuleId, expr_str: &str) -> CanExprOut
         })
         .collect();
 
-    //load builtin values
+    // load builtin values
     let (_introduced_rigids, constraint) =
         constrain_imported_values(imports, constraint, &var_store);
 
diff --git a/compiler/load/src/file.rs b/compiler/load/src/file.rs
index 6b7687f70c..659bb90e04 100644
--- a/compiler/load/src/file.rs
+++ b/compiler/load/src/file.rs
@@ -53,7 +53,7 @@ pub struct LoadedModule {
     pub solved: Solved<Subs>,
     pub can_problems: Vec<roc_problem::can::Problem>,
     pub type_problems: Vec<solve::TypeError>,
-    pub declarations: Vec<Declaration>,
+    pub declarations_by_id: MutMap<ModuleId, Vec<Declaration>>,
     pub exposed_vars_by_symbol: Vec<(Symbol, Variable)>,
     pub src: Box<str>,
 }
@@ -417,10 +417,6 @@ pub async fn load<'a>(
                         .into_inner()
                         .expect("Unwrapping mutex for module_ids");
 
-                    let declarations = declarations_by_id
-                        .remove(&module_id)
-                        .expect("declarations_by_id was missing root module_id entry");
-
                     let interns = Interns {
                         module_ids,
                         all_ident_ids: constrained_ident_ids,
@@ -432,7 +428,7 @@ pub async fn load<'a>(
                         solved,
                         can_problems,
                         type_problems,
-                        declarations,
+                        declarations_by_id,
                         exposed_vars_by_symbol,
                         src,
                     });
diff --git a/compiler/load/tests/test_load.rs b/compiler/load/tests/test_load.rs
index 058673bd7a..b54c1fd199 100644
--- a/compiler/load/tests/test_load.rs
+++ b/compiler/load/tests/test_load.rs
@@ -81,16 +81,18 @@ mod test_load {
         }
     }
 
-    fn expect_types(loaded_module: LoadedModule, expected_types: HashMap<&str, &str>) {
+    fn expect_types(mut loaded_module: LoadedModule, expected_types: HashMap<&str, &str>) {
         let home = loaded_module.module_id;
         let mut subs = loaded_module.solved.into_inner();
 
         assert_eq!(loaded_module.can_problems, Vec::new());
         assert_eq!(loaded_module.type_problems, Vec::new());
 
-        let num_decls = loaded_module.declarations.len();
+        let mut num_decls = 0;
+
+        for decl in loaded_module.declarations_by_id.remove(&home).unwrap() {
+            num_decls += 1;
 
-        for decl in loaded_module.declarations {
             match decl {
                 Declare(def) => expect_def(
                     &loaded_module.interns,
@@ -135,14 +137,17 @@ mod test_load {
                 subs_by_module,
             )
             .await;
-            let loaded_module = loaded.expect("Test module failed to load");
+
+            let mut loaded_module = loaded.expect("Test module failed to load");
 
             assert_eq!(loaded_module.can_problems, Vec::new());
             assert_eq!(loaded_module.type_problems, Vec::new());
 
             let def_count: usize = loaded_module
-                .declarations
-                .iter()
+                .declarations_by_id
+                .remove(&loaded_module.module_id)
+                .unwrap()
+                .into_iter()
                 .map(|decl| decl.def_count())
                 .sum();
 
diff --git a/compiler/load/tests/test_uniq_load.rs b/compiler/load/tests/test_uniq_load.rs
index 785b98ebe1..ee3360632e 100644
--- a/compiler/load/tests/test_uniq_load.rs
+++ b/compiler/load/tests/test_uniq_load.rs
@@ -76,16 +76,18 @@ mod test_uniq_load {
         }
     }
 
-    fn expect_types(loaded_module: LoadedModule, expected_types: HashMap<&str, &str>) {
+    fn expect_types(mut loaded_module: LoadedModule, expected_types: HashMap<&str, &str>) {
         let home = loaded_module.module_id;
         let mut subs = loaded_module.solved.into_inner();
 
         assert_eq!(loaded_module.can_problems, Vec::new());
         assert_eq!(loaded_module.type_problems, Vec::new());
 
-        let num_decls = loaded_module.declarations.len();
+        let mut num_decls = 0;
+
+        for decl in loaded_module.declarations_by_id.remove(&home).unwrap() {
+            num_decls += 1;
 
-        for decl in loaded_module.declarations {
             match decl {
                 Declare(def) => expect_def(
                     &loaded_module.interns,
@@ -130,14 +132,17 @@ mod test_uniq_load {
                 subs_by_module,
             )
             .await;
-            let loaded_module = loaded.expect("Test module failed to load");
+
+            let mut loaded_module = loaded.expect("Test module failed to load");
 
             assert_eq!(loaded_module.can_problems, Vec::new());
             assert_eq!(loaded_module.type_problems, Vec::new());
 
             let def_count: usize = loaded_module
-                .declarations
-                .iter()
+                .declarations_by_id
+                .remove(&loaded_module.module_id)
+                .unwrap()
+                .into_iter()
                 .map(|decl| decl.def_count())
                 .sum();
 
diff --git a/compiler/module/src/lib.rs b/compiler/module/src/lib.rs
index 78777141ce..b8a460f173 100644
--- a/compiler/module/src/lib.rs
+++ b/compiler/module/src/lib.rs
@@ -12,6 +12,7 @@
 #![allow(clippy::large_enum_variant)]
 
 pub mod ident;
+pub mod operator;
 pub mod symbol;
 
 #[macro_use]
diff --git a/compiler/parse/src/operator.rs b/compiler/module/src/operator.rs
similarity index 100%
rename from compiler/parse/src/operator.rs
rename to compiler/module/src/operator.rs
diff --git a/compiler/mono/src/expr.rs b/compiler/mono/src/expr.rs
index 62734a1f2c..e460d6434e 100644
--- a/compiler/mono/src/expr.rs
+++ b/compiler/mono/src/expr.rs
@@ -27,7 +27,8 @@ pub struct Proc<'a> {
 
 #[derive(Clone, Debug, PartialEq, Default)]
 pub struct Procs<'a> {
-    user_defined: MutMap<Symbol, PartialProc<'a>>,
+    pub user_defined: MutMap<Symbol, PartialProc<'a>>,
+    pub module_thunks: MutSet<Symbol>,
     anonymous: MutMap<Symbol, Option<Proc<'a>>>,
     specializations: MutMap<ContentHash, (Symbol, Option<Proc<'a>>)>,
     builtin: MutSet<Symbol>,
@@ -42,6 +43,66 @@ impl<'a> Procs<'a> {
         self.anonymous.insert(symbol, proc);
     }
 
+    pub fn insert_closure(
+        &mut self,
+        env: &mut Env<'a, '_>,
+        name: Option<Symbol>,
+        annotation: Variable,
+        loc_args: std::vec::Vec<(Variable, Located<roc_can::pattern::Pattern>)>,
+        loc_body: Located<roc_can::expr::Expr>,
+        ret_var: Variable,
+    ) -> Symbol {
+        // turn record/tag patterns into a when expression, e.g.
+        //
+        // foo = \{ x } -> body
+        //
+        // becomes
+        //
+        // foo = \r -> when r is { x } -> body
+        //
+        // conversion of one-pattern when expressions will do the most optimal thing
+
+        let (arg_vars, arg_symbols, body) = patterns_to_when(env, loc_args, ret_var, loc_body);
+
+        match name {
+            Some(symbol) => {
+                // a named closure
+                self.insert_user_defined(
+                    symbol,
+                    PartialProc {
+                        annotation,
+                        patterns: arg_symbols,
+                        body: body.value,
+                    },
+                );
+
+                symbol
+            }
+            None => {
+                // an anonymous closure. These will always be specialized already
+                // by the surrounding context
+                let symbol = env.fresh_symbol();
+
+                let opt_proc = specialize_proc_body(
+                    env,
+                    self,
+                    annotation,
+                    ret_var,
+                    symbol,
+                    &arg_vars,
+                    &arg_symbols,
+                    annotation,
+                    body.value,
+                )
+                .ok();
+
+                self.insert_anonymous(symbol, opt_proc);
+
+                symbol
+            }
+        }
+    }
+
     fn insert_specialization(
         &mut self,
         hash: ContentHash,
@@ -96,8 +157,8 @@ pub struct Env<'a, 'i> {
     pub home: ModuleId,
     pub ident_ids: &'i mut IdentIds,
     pub pointer_size: u32,
-    symbol_counter: usize,
     pub jump_counter: &'a mut u64,
+    pub symbol_counter: usize,
 }
 
 impl<'a, 'i> Env<'a, 'i> {
@@ -203,27 +264,11 @@ pub enum MonoProblem {
 #[allow(clippy::too_many_arguments)]
 impl<'a> Expr<'a> {
     pub fn new(
-        arena: &'a Bump,
-        subs: &'a mut Subs,
-        problems: &mut std::vec::Vec<MonoProblem>,
+        env: &mut Env<'a, '_>,
         can_expr: roc_can::expr::Expr,
         procs: &mut Procs<'a>,
-        home: ModuleId,
-        ident_ids: &mut IdentIds,
-        pointer_size: u32,
     ) -> Self {
-        let mut env = Env {
-            arena,
-            subs,
-            problems,
-            home,
-            ident_ids,
-            pointer_size,
-            symbol_counter: 0,
-            jump_counter: arena.alloc(0),
-        };
-
-        from_can(&mut env, can_expr, procs, None)
+        from_can(env, can_expr, procs, None)
     }
 }
 
@@ -426,61 +471,24 @@ fn from_can<'a>(
         Int(_, num) => Expr::Int(num),
         Float(_, num) => Expr::Float(num),
         Str(string) | BlockStr(string) => Expr::Str(env.arena.alloc(string)),
-        Var(symbol) => Expr::Load(symbol),
+        Var(symbol) => {
+            if procs.module_thunks.contains(&symbol) {
+                let partial_proc = procs.get_user_defined(symbol).unwrap();
+                let fn_var = partial_proc.annotation;
+                let ret_var = partial_proc.annotation;
+
+                // This is a top-level declaration, which will code gen to a 0-arity thunk.
+                call_by_name(env, procs, fn_var, ret_var, symbol, std::vec::Vec::new())
+            } else {
+                Expr::Load(symbol)
+            }
+        }
         LetRec(defs, ret_expr, _, _) => from_can_defs(env, defs, *ret_expr, procs),
         LetNonRec(def, ret_expr, _, _) => from_can_defs(env, vec![*def], *ret_expr, procs),
 
         Closure(annotation, _, _, loc_args, boxed_body) => {
             let (loc_body, ret_var) = *boxed_body;
-
-            // turn record/tag patterns into a when expression, e.g.
-            //
-            // foo = \{ x } -> body
-            //
-            // becomes
-            //
-            // foo = \r -> when r is { x } -> body
-            //
-            // conversion of one-pattern when expressions will do the most optimal thing
-
-            let (arg_vars, arg_symbols, body) = patterns_to_when(env, loc_args, ret_var, loc_body);
-
-            let symbol = match name {
-                Some(symbol) => {
-                    // a named closure
-                    procs.insert_user_defined(
-                        symbol,
-                        PartialProc {
-                            annotation,
-                            patterns: arg_symbols,
-                            body: body.value,
-                        },
-                    );
-                    symbol
-                }
-                None => {
-                    // an anonymous closure. These will always be specialized already
-                    // by the surrounding context
-                    let symbol = env.fresh_symbol();
-
-                    let opt_proc = specialize_proc_body(
-                        env,
-                        procs,
-                        annotation,
-                        ret_var,
-                        symbol,
-                        &arg_vars,
-                        &arg_symbols,
-                        annotation,
-                        body.value,
-                    )
-                    .ok();
-
-                    procs.insert_anonymous(symbol, opt_proc);
-
-                    symbol
-                }
-            };
+            let symbol = procs.insert_closure(env, name, annotation, loc_args, loc_body, ret_var);
 
             Expr::FunctionPointer(symbol)
         }
diff --git a/compiler/mono/tests/test_mono.rs b/compiler/mono/tests/test_mono.rs
index 8269fb347c..6c46c5639f 100644
--- a/compiler/mono/tests/test_mono.rs
+++ b/compiler/mono/tests/test_mono.rs
@@ -53,16 +53,17 @@ mod test_mono {
 
         // Populate Procs and Subs, and get the low-level Expr from the canonical Expr
         let mut mono_problems = Vec::new();
-        let mono_expr = Expr::new(
-            &arena,
-            &mut subs,
-            &mut mono_problems,
-            loc_expr.value,
-            &mut procs,
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
             home,
-            &mut ident_ids,
+            ident_ids: &mut ident_ids,
             pointer_size,
-        );
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let mono_expr = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         // Put this module's ident_ids back in the interns
         interns.all_ident_ids.insert(home, ident_ids);
diff --git a/compiler/mono/tests/test_opt.rs b/compiler/mono/tests/test_opt.rs
index 6cdde4c792..b93aff0e58 100644
--- a/compiler/mono/tests/test_opt.rs
+++ b/compiler/mono/tests/test_opt.rs
@@ -42,16 +42,17 @@ mod test_opt {
 
         // Populate Procs and Subs, and get the low-level Expr from the canonical Expr
         let mut mono_problems = Vec::new();
-        let mono_expr = Expr::new(
-            &arena,
-            &mut subs,
-            &mut mono_problems,
-            loc_expr.value,
-            &mut procs,
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
             home,
-            &mut ident_ids,
+            ident_ids: &mut ident_ids,
             pointer_size,
-        );
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let mono_expr = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         let unexpected_calls = extract_named_calls(&mono_expr, &mut calls);
         let expected = CallProblems::default();
@@ -193,16 +194,17 @@ mod test_opt {
 
         // Populate Procs and Subs, and get the low-level Expr from the canonical Expr
         let mut mono_problems = Vec::new();
-        let mono_expr = Expr::new(
-            &arena,
-            &mut subs,
-            &mut mono_problems,
-            loc_expr.value,
-            &mut procs,
+        let mut mono_env = roc_mono::expr::Env {
+            arena: &arena,
+            subs: &mut subs,
+            problems: &mut mono_problems,
             home,
-            &mut ident_ids,
+            ident_ids: &mut ident_ids,
             pointer_size,
-        );
+            symbol_counter: 0,
+            jump_counter: arena.alloc(0),
+        };
+        let mono_expr = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
 
         assert_eq!(mono_expr, expected);
     }
diff --git a/compiler/parse/src/ast.rs b/compiler/parse/src/ast.rs
index d24ea05ad7..b7386146ad 100644
--- a/compiler/parse/src/ast.rs
+++ b/compiler/parse/src/ast.rs
@@ -1,10 +1,9 @@
 use crate::header::ModuleName;
 use crate::ident::Ident;
-use crate::operator::CalledVia;
-use crate::operator::{BinOp, UnaryOp};
 use bumpalo::collections::String;
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
+use roc_module::operator::{BinOp, CalledVia, UnaryOp};
 use roc_region::all::{Loc, Region};
 
 #[derive(Clone, Debug, PartialEq)]
diff --git a/compiler/parse/src/expr.rs b/compiler/parse/src/expr.rs
index b09240a658..87acc8649c 100644
--- a/compiler/parse/src/expr.rs
+++ b/compiler/parse/src/expr.rs
@@ -7,7 +7,6 @@ use crate::blankspace::{
 use crate::ident::{global_tag_or_ident, ident, lowercase_ident, Ident};
 use crate::keyword;
 use crate::number_literal::number_literal;
-use crate::operator::{BinOp, CalledVia, UnaryOp};
 use crate::parser::{
     self, allocated, char, fail, not, not_followed_by, optional, sep_by1, string, then, unexpected,
     unexpected_eof, Either, Fail, FailReason, ParseResult, Parser, State,
@@ -16,6 +15,7 @@ use crate::type_annotation;
 use bumpalo::collections::string::String;
 use bumpalo::collections::Vec;
 use bumpalo::Bump;
+use roc_module::operator::{BinOp, CalledVia, UnaryOp};
 use roc_region::all::{Located, Region};
 
 pub fn expr<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>> {
diff --git a/compiler/parse/src/lib.rs b/compiler/parse/src/lib.rs
index 6920568252..af7f71fbcf 100644
--- a/compiler/parse/src/lib.rs
+++ b/compiler/parse/src/lib.rs
@@ -21,7 +21,6 @@ pub mod ident;
 pub mod keyword;
 pub mod module;
 pub mod number_literal;
-pub mod operator;
 pub mod pattern;
 pub mod problems;
 pub mod string_literal;
diff --git a/compiler/parse/tests/test_parse.rs b/compiler/parse/tests/test_parse.rs
index c66e250cc0..7c71a92415 100644
--- a/compiler/parse/tests/test_parse.rs
+++ b/compiler/parse/tests/test_parse.rs
@@ -18,6 +18,8 @@ mod test_parse {
     use crate::helpers::parse_with;
     use bumpalo::collections::vec::Vec;
     use bumpalo::{self, Bump};
+    use roc_module::operator::BinOp::*;
+    use roc_module::operator::{CalledVia, UnaryOp};
     use roc_parse::ast::AssignedField::*;
     use roc_parse::ast::CommentOrNewline::*;
     use roc_parse::ast::Expr::{self, *};
@@ -27,9 +29,6 @@ mod test_parse {
     };
     use roc_parse::header::ModuleName;
     use roc_parse::module::{interface_header, module_defs};
-    use roc_parse::operator::BinOp::*;
-    use roc_parse::operator::CalledVia;
-    use roc_parse::operator::UnaryOp;
     use roc_parse::parser::{Fail, FailReason, Parser, State};
     use roc_region::all::{Located, Region};
     use std::{f64, i64};
diff --git a/compiler/problem/src/can.rs b/compiler/problem/src/can.rs
index 0035b7a5b8..5f83be28b0 100644
--- a/compiler/problem/src/can.rs
+++ b/compiler/problem/src/can.rs
@@ -1,8 +1,8 @@
 use inlinable_string::InlinableString;
 use roc_collections::all::MutSet;
 use roc_module::ident::{Ident, Lowercase, TagName};
+use roc_module::operator::BinOp;
 use roc_module::symbol::{ModuleId, Symbol};
-use roc_parse::operator::BinOp;
 use roc_parse::pattern::PatternType;
 use roc_region::all::{Located, Region};
 
diff --git a/compiler/reporting/src/report.rs b/compiler/reporting/src/report.rs
index 25cb34c2a9..124bec113a 100644
--- a/compiler/reporting/src/report.rs
+++ b/compiler/reporting/src/report.rs
@@ -299,7 +299,7 @@ impl<'a> RocDocAllocator<'a> {
 
     pub fn binop(
         &'a self,
-        content: roc_parse::operator::BinOp,
+        content: roc_module::operator::BinOp,
     ) -> DocBuilder<'a, Self, Annotation> {
         self.text(content.to_string()).annotate(Annotation::BinOp)
     }
diff --git a/compiler/reporting/tests/test_reporting.rs b/compiler/reporting/tests/test_reporting.rs
index 23225fffef..7b0bc1bc03 100644
--- a/compiler/reporting/tests/test_reporting.rs
+++ b/compiler/reporting/tests/test_reporting.rs
@@ -90,16 +90,17 @@ mod test_reporting {
             let pointer_size = std::mem::size_of::<u64>() as u32;
 
             // Populate Procs and Subs, and get the low-level Expr from the canonical Expr
-            let _mono_expr = Expr::new(
-                &arena,
-                &mut subs,
-                &mut mono_problems,
-                loc_expr.value,
-                &mut procs,
+            let mut mono_env = roc_mono::expr::Env {
+                arena: &arena,
+                subs: &mut subs,
+                problems: &mut mono_problems,
                 home,
-                &mut ident_ids,
+                ident_ids: &mut ident_ids,
                 pointer_size,
-            );
+                symbol_counter: 0,
+                jump_counter: arena.alloc(0),
+            };
+            let _mono_expr = Expr::new(&mut mono_env, loc_expr.value, &mut procs);
         }
 
         Ok((unify_problems, can_problems, mono_problems, home, interns))
diff --git a/examples/hello-world/Hello.roc b/examples/hello-world/Hello.roc
index ef6ba9f212..0d3d072597 100644
--- a/examples/hello-world/Hello.roc
+++ b/examples/hello-world/Hello.roc
@@ -1,3 +1,8 @@
 app Hello provides [ main ] imports []
 
-main = "Hello, World!"
+greeting =
+    hi = "Hello, World!"
+
+    hi
+
+main = greeting