refactor: less unwrap

nix-js/runtime-ts/src/helpers.ts

@@ -2,8 +2,9 @@
  * Helper functions for nix-js runtime
  */
 
-import type { NixValue, NixAttrs } from "./types";
+import type { NixValue, NixAttrs, NixBool } from "./types";
 import { force_attrs, force_string } from "./type-assert";
+import { isAttrs } from "./builtins/type-check";
 
 /**
  * Resolve a path (handles both absolute and relative paths)
@@ -47,14 +48,9 @@ export const select = (obj: NixValue, key: NixValue): NixValue => {
  * @returns obj[key] if exists, otherwise default_val
  */
 export const select_with_default = (obj: NixValue, key: NixValue, default_val: NixValue): NixValue => {
-  const forced_obj = force_attrs(obj);
+  const attrs = force_attrs(obj);
   const forced_key = force_string(key);
 
-  if (forced_obj === null || forced_obj === undefined) {
-    return default_val;
-  }
-
-  const attrs = forced_obj;
   if (!(forced_key in attrs)) {
     return default_val;
   }
@@ -62,6 +58,23 @@ export const select_with_default = (obj: NixValue, key: NixValue, default_val: N
   return attrs[forced_key];
 };
 
+export const has_attr = (obj: NixValue, attrpath: NixValue[]): NixBool => {
+  if (!isAttrs(obj)) {
+    return false
+  }
+  let attrs = obj;
+
+  for (const attr of attrpath.slice(0, -1)) {
+    const cur = attrs[force_string(attr)];
+    if (!isAttrs(cur)) {
+      return false;
+    }
+    attrs = cur;
+  }
+
+  return true;
+};
+
 /**
  * Validate function parameters
  * Used for pattern matching in function parameters

nix-js/runtime-ts/src/index.ts

@@ -5,7 +5,7 @@
  */
 
 import { create_thunk, force, is_thunk, IS_THUNK } from "./thunk";
-import { select, select_with_default, validate_params, resolve_path } from "./helpers";
+import { select, select_with_default, validate_params, resolve_path, has_attr } from "./helpers";
 import { op } from "./operators";
 import { builtins, PRIMOP_METADATA } from "./builtins";
 
@@ -20,6 +20,7 @@ export const Nix = {
   is_thunk,
   IS_THUNK,
 
+  has_attr,
   select,
   select_with_default,
   validate_params,

nix-js/src/bin/eval.rs

@@ -10,7 +10,7 @@ fn main() -> Result<()> {
     }
     args.next();
     let expr = args.next().unwrap();
-    match Context::new().eval_code(&expr) {
+    match Context::new()?.eval_code(&expr) {
         Ok(value) => {
             println!("{value}");
             Ok(())

nix-js/src/bin/repl.rs

@@ -7,7 +7,7 @@ use nix_js::context::Context;
 
 fn main() -> Result<()> {
     let mut rl = DefaultEditor::new()?;
-    let mut context = Context::new();
+    let mut context = Context::new()?;
     let re = Regex::new(r"^\s*([a-zA-Z_][a-zA-Z0-9_'-]*)\s*=(.*)$").unwrap();
     loop {
         let readline = rl.readline("nix-js-repl> ");

nix-js/src/codegen.rs

@@ -18,14 +18,20 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Ir {
             Ir::Float(float) => float.to_string(),
             Ir::Str(s) => {
                 // Escape string for JavaScript
-                let escaped = s
+                let mut escaped = String::with_capacity(s.val.len() + 2);
-                    .val
+                escaped.push('"');
-                    .replace('\\', "\\\\")
+                for c in s.val.chars() {
-                    .replace('"', "\\\"")
+                    match c {
-                    .replace('\n', "\\n")
+                        '\\' => escaped.push_str("\\\\"),
-                    .replace('\r', "\\r")
+                        '\"' => escaped.push_str("\\\""),
-                    .replace('\t', "\\t");
+                        '\n' => escaped.push_str("\\n"),
-                format!("\"{}\"", escaped)
+                        '\r' => escaped.push_str("\\r"),
+                        '\t' => escaped.push_str("\\t"),
+                        _ => escaped.push(c),
+                    }
+                }
+                escaped.push('"');
+                escaped
             }
             Ir::Path(p) => {
                 // Path needs runtime resolution for interpolated paths
@@ -88,8 +94,8 @@ impl<Ctx: CodegenContext> Compile<Ctx> for BinOp {
             Leq => format!("Nix.op.lte({},{})", lhs, rhs),
             Geq => format!("Nix.op.gte({},{})", lhs, rhs),
             // Short-circuit operators: use JavaScript native && and ||
-            And => format!("(Nix.force({}) && Nix.force({}))", lhs, rhs),
+            And => format!("Nix.force({}) && Nix.force({})", lhs, rhs),
-            Or => format!("(Nix.force({}) || Nix.force({}))", lhs, rhs),
+            Or => format!("Nix.force({}) || Nix.force({})", lhs, rhs),
             Impl => format!("(!Nix.force({}) || Nix.force({}))", lhs, rhs),
             Con => format!("Nix.op.concat({},{})", lhs, rhs),
             Upd => format!("Nix.op.update({},{})", lhs, rhs),
@@ -202,13 +208,13 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Select {
 
         for (i, attr) in self.attrpath.iter().enumerate() {
             let is_last = i == attr_count - 1;
-            let has_default = self.default.is_some() && is_last;
-
             result = match attr {
                 Attr::Str(sym) => {
                     let key = ctx.get_sym(*sym);
-                    if has_default {
+                    if let Some(default) = self.default
-                        let default_val = ctx.get_ir(self.default.unwrap()).compile(ctx);
+                        && is_last
+                    {
+                        let default_val = ctx.get_ir(default).compile(ctx);
                         format!(
                             "Nix.select_with_default({}, \"{}\", {})",
                             result, key, default_val
@@ -219,8 +225,10 @@ impl<Ctx: CodegenContext> Compile<Ctx> for Select {
                 }
                 Attr::Dynamic(expr_id) => {
                     let key = ctx.get_ir(*expr_id).compile(ctx);
-                    if has_default {
+                    if let Some(default) = self.default
-                        let default_val = ctx.get_ir(self.default.unwrap()).compile(ctx);
+                        && is_last
+                    {
+                        let default_val = ctx.get_ir(default).compile(ctx);
                         format!(
                             "Nix.select_with_default({}, {}, {})",
                             result, key, default_val
@@ -289,29 +297,16 @@ impl<Ctx: CodegenContext> Compile<Ctx> for ConcatStrings {
 impl<Ctx: CodegenContext> Compile<Ctx> for HasAttr {
     fn compile(&self, ctx: &Ctx) -> String {
         let lhs = ctx.get_ir(self.lhs).compile(ctx);
-
+        let attrpath = self
-        // Build attrpath check
+            .rhs
-        let mut current = format!("Nix.force({})", lhs);
+            .iter()
-
+            .map(|attr| match attr {
-        for attr in &self.rhs {
-            match attr {
                 Attr::Str(sym) => {
-                    let key = ctx.get_sym(*sym);
+                    format!("\"{}\"", ctx.get_sym(*sym))
-                    current = format!(
-                        "(Nix.force({}) !== null && Nix.force({}) !== undefined && \"{}\" in Nix.force({}))",
-                        current, current, key, current
-                    );
                 }
-                Attr::Dynamic(expr_id) => {
+                Attr::Dynamic(expr_id) => ctx.get_ir(*expr_id).compile(ctx),
-                    let key = ctx.get_ir(*expr_id).compile(ctx);
+            })
-                    current = format!(
+            .join(",");
-                        "(Nix.force({}) !== null && Nix.force({}) !== undefined && Nix.force({}) in Nix.force({}))",
+        format!("Nix.has_attr({lhs}, [{attrpath}])")
-                        current, current, key, current
-                    );
-                }
-            }
-        }
-
-        current
     }
 }

nix-js/src/context.rs

@@ -21,12 +21,6 @@ pub struct Context {
     runtime: Runtime,
 }
 
-impl Default for Context {
-    fn default() -> Self {
-        Self::new()
-    }
-}
-
 pub(crate) struct CtxPtr(NonNull<Ctx>);
 impl CtxPtr {
     pub(crate) unsafe fn as_ref(&self) -> &Ctx {
@@ -38,23 +32,26 @@ impl CtxPtr {
 }
 
 impl Context {
-    pub fn new() -> Self {
+    pub fn new() -> Result<Self> {
         let mut ctx = Box::pin(Ctx::new());
         let ptr = unsafe { CtxPtr(NonNull::new_unchecked(Pin::get_unchecked_mut(ctx.as_mut()))) };
-        let runtime = Runtime::new(ptr);
+        let runtime = Runtime::new(ptr)?;
 
-        Self { ctx, runtime }
+        Ok(Self { ctx, runtime })
     }
 
     pub fn eval_code(&mut self, expr: &str) -> Result<Value> {
         // Initialize `path_stack` with current directory for relative path resolution
-        let mut guard = PathDropGuard::new_cwd(self.ctx.as_mut());
+        let mut guard = PathDropGuard::new_cwd(self.ctx.as_mut())?;
         let ctx = guard.as_ctx();
 
         let root = rnix::Root::parse(expr);
         if !root.errors().is_empty() {
             return Err(Error::parse_error(root.errors().iter().join("; ")));
         }
+
+        #[allow(clippy::unwrap_used)]
+        // Always `Some` since there is no parse error
         let root = ctx
             .as_mut()
             .downgrade_ctx()
@@ -99,11 +96,12 @@ impl<'ctx> PathDropGuard<'ctx> {
         ctx.as_mut().project().path_stack.push(path);
         Self { ctx }
     }
-    pub(crate) fn new_cwd(mut ctx: Pin<&'ctx mut Ctx>) -> Self {
+    pub(crate) fn new_cwd(mut ctx: Pin<&'ctx mut Ctx>) -> Result<Self> {
-        let cwd = std::env::current_dir().unwrap();
+        let cwd = std::env::current_dir()
+            .map_err(|err| Error::downgrade_error(format!("cannot get cwd: {err}")))?;
         let virtual_file = cwd.join("__eval__.nix");
         ctx.as_mut().project().path_stack.push(virtual_file);
-        Self { ctx }
+        Ok(Self { ctx })
     }
     pub(crate) fn as_ctx<'a>(&'a mut self) -> &'a mut Pin<&'ctx mut Ctx> {
         &mut self.ctx
@@ -185,24 +183,27 @@ impl Ctx {
     pub(crate) fn get_current_dir(&self) -> PathBuf {
         self.path_stack
             .last()
-            .unwrap()
+            .expect(
+                "path_stack should never be empty when get_current_dir is called. this is a bug",
+            )
             .parent()
-            .unwrap()
+            .expect("path in path_stack should always have a parent dir. this is a bug")
             .to_path_buf()
     }
 }
 
 impl CodegenContext for Ctx {
     fn get_ir(&self, id: ExprId) -> &Ir {
-        self.irs.get(id.0).unwrap()
+        self.irs.get(id.0).expect("ExprId out of bounds")
     }
 
     fn get_sym(&self, id: SymId) -> &str {
-        self.symbols.resolve(id).unwrap()
+        self.symbols.resolve(id).expect("SymId out of bounds")
     }
 }
 
 #[cfg(test)]
+#[allow(clippy::unwrap_used)]
 mod test {
     use std::collections::BTreeMap;
 
@@ -211,26 +212,42 @@ mod test {
 
     #[test]
     fn basic_eval() {
-        assert_eq!(Context::new().eval_code("1 + 1").unwrap(), Value::Int(2));
-        assert_eq!(Context::new().eval_code("(x: x) 1").unwrap(), Value::Int(1));
         assert_eq!(
-            Context::new().eval_code("(x: y: x - y) 2 1").unwrap(),
+            Context::new().unwrap().eval_code("1 + 1").unwrap(),
+            Value::Int(2)
+        );
+        assert_eq!(
+            Context::new().unwrap().eval_code("(x: x) 1").unwrap(),
             Value::Int(1)
         );
         assert_eq!(
-            Context::new().eval_code("rec { b = a; a = 1; }.b").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("(x: y: x - y) 2 1")
+                .unwrap(),
             Value::Int(1)
         );
         assert_eq!(
-            Context::new().eval_code("let b = a; a = 1; in b").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("rec { b = a; a = 1; }.b")
+                .unwrap(),
             Value::Int(1)
         );
         assert_eq!(
-            Context::new().eval_code("let fib = n: if n == 1 || n == 2 then 1 else (fib (n - 1)) + (fib (n - 2)); in fib 30").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("let b = a; a = 1; in b")
+                .unwrap(),
+            Value::Int(1)
+        );
+        assert_eq!(
+            Context::new().unwrap().eval_code("let fib = n: if n == 1 || n == 2 then 1 else (fib (n - 1)) + (fib (n - 2)); in fib 30").unwrap(),
             Value::Int(832040)
         );
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("((f: let x = f x; in x)(self: { x = 1; y = self.x + 1; })).y")
                 .unwrap(),
             Value::Int(2)
@@ -272,7 +289,7 @@ mod test {
             ),
         ];
         for (expr, expected) in tests {
-            assert_eq!(Context::new().eval_code(expr).unwrap(), expected);
+            assert_eq!(Context::new().unwrap().eval_code(expr).unwrap(), expected);
         }
     }
 
@@ -281,18 +298,22 @@ mod test {
         // Test function with required parameters
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("({ a, b }: a + b) { a = 1; b = 2; }")
                 .unwrap(),
             Value::Int(3)
         );
 
         // Test missing required parameter should fail
-        let result = Context::new().eval_code("({ a, b }: a + b) { a = 1; }");
+        let result = Context::new()
+            .unwrap()
+            .eval_code("({ a, b }: a + b) { a = 1; }");
         assert!(result.is_err());
 
         // Test all required parameters present
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("({ x, y, z }: x + y + z) { x = 1; y = 2; z = 3; }")
                 .unwrap(),
             Value::Int(6)
@@ -302,12 +323,15 @@ mod test {
     #[test]
     fn test_param_check_allowed() {
         // Test function without ellipsis - should reject unexpected arguments
-        let result = Context::new().eval_code("({ a, b }: a + b) { a = 1; b = 2; c = 3; }");
+        let result = Context::new()
+            .unwrap()
+            .eval_code("({ a, b }: a + b) { a = 1; b = 2; c = 3; }");
         assert!(result.is_err());
 
         // Test function with ellipsis - should accept extra arguments
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("({ a, b, ... }: a + b) { a = 1; b = 2; c = 3; }")
                 .unwrap(),
             Value::Int(3)
@@ -319,6 +343,7 @@ mod test {
         // Test function with default parameters
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("({ a, b ? 5 }: a + b) { a = 1; }")
                 .unwrap(),
             Value::Int(6)
@@ -327,6 +352,7 @@ mod test {
         // Test overriding default parameter
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("({ a, b ? 5 }: a + b) { a = 1; b = 10; }")
                 .unwrap(),
             Value::Int(11)
@@ -338,6 +364,7 @@ mod test {
         // Test function with @ pattern (alias)
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("(args@{ a, b }: args.a + args.b) { a = 1; b = 2; }")
                 .unwrap(),
             Value::Int(3)
@@ -349,6 +376,7 @@ mod test {
         // Test simple parameter (no pattern) should not have validation
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("(x: x.a + x.b) { a = 1; b = 2; }")
                 .unwrap(),
             Value::Int(3)
@@ -356,7 +384,7 @@ mod test {
 
         // Simple parameter accepts any argument
         assert_eq!(
-            Context::new().eval_code("(x: x) 42").unwrap(),
+            Context::new().unwrap().eval_code("(x: x) 42").unwrap(),
             Value::Int(42)
         );
     }
@@ -364,7 +392,7 @@ mod test {
     #[test]
     fn test_builtins_basic_access() {
         // Test that builtins identifier is accessible
-        let result = Context::new().eval_code("builtins").unwrap();
+        let result = Context::new().unwrap().eval_code("builtins").unwrap();
         // Should return an AttrSet with builtin functions
         assert!(matches!(result, Value::AttrSet(_)));
     }
@@ -372,7 +400,10 @@ mod test {
     #[test]
     fn test_builtins_self_reference() {
         // Test builtins.builtins (self-reference as thunk)
-        let result = Context::new().eval_code("builtins.builtins").unwrap();
+        let result = Context::new()
+            .unwrap()
+            .eval_code("builtins.builtins")
+            .unwrap();
         assert!(matches!(result, Value::AttrSet(_)));
     }
 
@@ -380,7 +411,10 @@ mod test {
     fn test_builtin_function_add() {
         // Test calling builtin function: builtins.add 1 2
         assert_eq!(
-            Context::new().eval_code("builtins.add 1 2").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.add 1 2")
+                .unwrap(),
             Value::Int(3)
         );
     }
@@ -389,7 +423,10 @@ mod test {
     fn test_builtin_function_length() {
         // Test builtin with list: builtins.length [1 2 3]
         assert_eq!(
-            Context::new().eval_code("builtins.length [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.length [1 2 3]")
+                .unwrap(),
             Value::Int(3)
         );
     }
@@ -398,7 +435,10 @@ mod test {
     fn test_builtin_function_map() {
         // Test higher-order builtin: map (x: x * 2) [1 2 3]
         assert_eq!(
-            Context::new().eval_code("map (x: x * 2) [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("map (x: x * 2) [1 2 3]")
+                .unwrap(),
             Value::List(List::new(
                 vec![Value::Int(2), Value::Int(4), Value::Int(6),]
             ))
@@ -410,6 +450,7 @@ mod test {
         // Test predicate builtin: builtins.filter (x: x > 1) [1 2 3]
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("builtins.filter (x: x > 1) [1 2 3]")
                 .unwrap(),
             Value::List(List::new(vec![Value::Int(2), Value::Int(3),]))
@@ -420,6 +461,7 @@ mod test {
     fn test_builtin_function_attrnames() {
         // Test builtins.attrNames { a = 1; b = 2; }
         let result = Context::new()
+            .unwrap()
             .eval_code("builtins.attrNames { a = 1; b = 2; }")
             .unwrap();
         // Should return a list of attribute names
@@ -434,7 +476,10 @@ mod test {
     fn test_builtin_function_head() {
         // Test builtins.head [1 2 3]
         assert_eq!(
-            Context::new().eval_code("builtins.head [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.head [1 2 3]")
+                .unwrap(),
             Value::Int(1)
         );
     }
@@ -443,7 +488,10 @@ mod test {
     fn test_builtin_function_tail() {
         // Test builtins.tail [1 2 3]
         assert_eq!(
-            Context::new().eval_code("builtins.tail [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.tail [1 2 3]")
+                .unwrap(),
             Value::List(List::new(vec![Value::Int(2), Value::Int(3),]))
         );
     }
@@ -453,6 +501,7 @@ mod test {
         // Test builtins in let binding
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("let b = builtins; in b.add 5 3")
                 .unwrap(),
             Value::Int(8)
@@ -464,6 +513,7 @@ mod test {
         // Test builtins with 'with' expression
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("with builtins; add 10 20")
                 .unwrap(),
             Value::Int(30)
@@ -475,6 +525,7 @@ mod test {
         // Test nested function calls with builtins
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("builtins.add (builtins.mul 2 3) (builtins.sub 10 5)")
                 .unwrap(),
             Value::Int(11) // (2*3) + (10-5 = 6 + 5 = 11
@@ -485,27 +536,38 @@ mod test {
     fn test_builtin_type_checks() {
         // Test type checking functions
         assert_eq!(
-            Context::new().eval_code("builtins.isList [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.isList [1 2 3]")
+                .unwrap(),
             Value::Bool(true)
         );
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("builtins.isAttrs { a = 1; }")
                 .unwrap(),
             Value::Bool(true)
         );
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("builtins.isFunction (x: x)")
                 .unwrap(),
             Value::Bool(true)
         );
         assert_eq!(
-            Context::new().eval_code("builtins.isNull null").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.isNull null")
+                .unwrap(),
             Value::Bool(true)
         );
         assert_eq!(
-            Context::new().eval_code("builtins.isBool true").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("builtins.isBool true")
+                .unwrap(),
             Value::Bool(true)
         );
     }
@@ -515,6 +577,7 @@ mod test {
         // Test that user can shadow builtins (Nix allows this)
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("let builtins = { add = x: y: x - y; }; in builtins.add 5 3")
                 .unwrap(),
             Value::Int(2) // Uses shadowed version
@@ -526,6 +589,7 @@ mod test {
         // Test that builtins.builtins is lazy (thunk)
         // This should not cause infinite recursion
         let result = Context::new()
+            .unwrap()
             .eval_code("builtins.builtins.builtins.add 1 1")
             .unwrap();
         assert_eq!(result, Value::Int(2));
@@ -534,27 +598,36 @@ mod test {
     // Free globals tests
     #[test]
     fn test_free_global_true() {
-        assert_eq!(Context::new().eval_code("true").unwrap(), Value::Bool(true));
+        assert_eq!(
+            Context::new().unwrap().eval_code("true").unwrap(),
+            Value::Bool(true)
+        );
     }
 
     #[test]
     fn test_free_global_false() {
         assert_eq!(
-            Context::new().eval_code("false").unwrap(),
+            Context::new().unwrap().eval_code("false").unwrap(),
             Value::Bool(false)
         );
     }
 
     #[test]
     fn test_free_global_null() {
-        assert_eq!(Context::new().eval_code("null").unwrap(), Value::Null);
+        assert_eq!(
+            Context::new().unwrap().eval_code("null").unwrap(),
+            Value::Null
+        );
     }
 
     #[test]
     fn test_free_global_map() {
         // Test free global function: map (x: x * 2) [1 2 3]
         assert_eq!(
-            Context::new().eval_code("map (x: x * 2) [1 2 3]").unwrap(),
+            Context::new()
+                .unwrap()
+                .eval_code("map (x: x * 2) [1 2 3]")
+                .unwrap(),
             Value::List(List::new(
                 vec![Value::Int(2), Value::Int(4), Value::Int(6),]
             ))
@@ -565,11 +638,11 @@ mod test {
     fn test_free_global_isnull() {
         // Test isNull function
         assert_eq!(
-            Context::new().eval_code("isNull null").unwrap(),
+            Context::new().unwrap().eval_code("isNull null").unwrap(),
             Value::Bool(true)
         );
         assert_eq!(
-            Context::new().eval_code("isNull 5").unwrap(),
+            Context::new().unwrap().eval_code("isNull 5").unwrap(),
             Value::Bool(false)
         );
     }
@@ -579,12 +652,14 @@ mod test {
         // Test shadowing of free globals
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("let true = false; in true")
                 .unwrap(),
             Value::Bool(false)
         );
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("let map = x: y: x; in map 1 2")
                 .unwrap(),
             Value::Int(1)
@@ -596,6 +671,7 @@ mod test {
         // Test mixing free globals in expressions
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("if true then map (x: x + 1) [1 2] else []")
                 .unwrap(),
             Value::List(List::new(vec![Value::Int(2), Value::Int(3),]))
@@ -607,6 +683,7 @@ mod test {
         // Test free globals in let bindings
         assert_eq!(
             Context::new()
+                .unwrap()
                 .eval_code("let x = true; y = false; in x && y")
                 .unwrap(),
             Value::Bool(false)
@@ -616,7 +693,7 @@ mod test {
     // BigInt and numeric type tests
     #[test]
     fn test_bigint_precision() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         // Test large i64 values
         assert_eq!(
@@ -641,7 +718,7 @@ mod test {
 
     #[test]
     fn test_int_float_distinction() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         // isInt tests
         assert_eq!(
@@ -688,7 +765,7 @@ mod test {
 
     #[test]
     fn test_arithmetic_type_preservation() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         // int + int = int
         assert_eq!(
@@ -717,7 +794,7 @@ mod test {
 
     #[test]
     fn test_integer_division() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         assert_eq!(ctx.eval_code("5 / 2").unwrap(), Value::Int(2));
 
@@ -735,7 +812,7 @@ mod test {
 
     #[test]
     fn test_builtin_arithmetic_with_bigint() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         // Test builtin add with large numbers
         assert_eq!(
@@ -753,7 +830,7 @@ mod test {
 
     #[test]
     fn test_import_absolute_path() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         let temp_dir = tempfile::tempdir().unwrap();
         let lib_path = temp_dir.path().join("nix_test_lib.nix");
@@ -766,7 +843,7 @@ mod test {
 
     #[test]
     fn test_import_nested() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         let temp_dir = tempfile::tempdir().unwrap();
 
@@ -786,7 +863,7 @@ mod test {
 
     #[test]
     fn test_import_relative_path() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         let temp_dir = tempfile::tempdir().unwrap();
         let subdir = temp_dir.path().join("subdir");
@@ -819,7 +896,7 @@ mod test {
 
     #[test]
     fn test_import_returns_function() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
 
         let temp_dir = tempfile::tempdir().unwrap();
         let func_path = temp_dir.path().join("nix_test_func.nix");

nix-js/src/context/downgrade.rs

@@ -2,6 +2,7 @@ use std::pin::Pin;
 
 use hashbrown::HashMap;
 
+use crate::codegen::CodegenContext;
 use crate::error::{Error, Result};
 use crate::ir::{ArgId, Downgrade, DowngradeContext, ExprId, Ir, SymId, ToIr};
 
@@ -65,7 +66,7 @@ impl DowngradeContext for DowngradeCtx<'_> {
     }
 
     fn get_sym(&self, id: SymId) -> &str {
-        self.ctx.symbols.resolve(id).unwrap()
+        self.ctx.get_sym(id)
     }
 
     fn lookup(&mut self, sym: SymId) -> Result<ExprId> {
@@ -117,12 +118,20 @@ impl DowngradeContext for DowngradeCtx<'_> {
 
     fn extract_expr(&mut self, id: ExprId) -> Ir {
         let local_id = id.0 - self.ctx.irs.len();
-        self.irs.get_mut(local_id).unwrap().take().unwrap()
+        self.irs
+            .get_mut(local_id)
+            .expect("ExprId out of bounds")
+            .take()
+            .expect("extract_expr called on an already extracted expr")
     }
 
     fn replace_expr(&mut self, id: ExprId, expr: Ir) {
         let local_id = id.0 - self.ctx.irs.len();
-        let _ = self.irs.get_mut(local_id).unwrap().insert(expr);
+        let _ = self
+            .irs
+            .get_mut(local_id)
+            .expect("ExprId out of bounds")
+            .insert(expr);
     }
 
     #[allow(refining_impl_trait)]

nix-js/src/error.rs

@@ -1,4 +1,4 @@
-use std::rc::Rc;
+use std::sync::Arc;
 use thiserror::Error;
 
 pub type Result<T> = core::result::Result<T, Error>;
@@ -11,6 +11,8 @@ pub enum ErrorKind {
     DowngradeError(String),
     #[error("error occurred during evaluation stage: {0}")]
     EvalError(String),
+    #[error("internal error occurred: {0}")]
+    InternalError(String),
     #[error("{0}")]
     Catchable(String),
     #[error("an unknown or unexpected error occurred")]
@@ -21,7 +23,7 @@ pub enum ErrorKind {
 pub struct Error {
     pub kind: ErrorKind,
     pub span: Option<rnix::TextRange>,
-    pub source: Option<Rc<str>>,
+    pub source: Option<Arc<str>>,
 }
 
 impl std::fmt::Display for Error {
@@ -101,7 +103,7 @@ impl Error {
         self
     }
 
-    pub fn with_source(mut self, source: Rc<str>) -> Self {
+    pub fn with_source(mut self, source: Arc<str>) -> Self {
         self.source = Some(source);
         self
     }
@@ -115,6 +117,9 @@ impl Error {
     pub fn eval_error(msg: String) -> Self {
         Self::new(ErrorKind::EvalError(msg))
     }
+    pub fn internal(msg: String) -> Self {
+        Self::new(ErrorKind::InternalError(msg))
+    }
     pub fn catchable(msg: String) -> Self {
         Self::new(ErrorKind::Catchable(msg))
     }

nix-js/src/ir.rs

@@ -141,7 +141,9 @@ impl AttrSet {
     ) -> Result<()> {
         let mut path = path.into_iter();
         // The last part of the path is the name of the attribute to be inserted.
-        let name = path.next_back().unwrap();
+        let name = path
+            .next_back()
+            .expect("empty attrpath passed. this is a bug");
         self._insert(path, name, value, ctx)
     }
 }

nix-js/src/ir/downgrade.rs

@@ -1,3 +1,6 @@
+// Assume no parse error
+#![allow(clippy::unwrap_used)]
+
 use rnix::ast::{self, Expr, HasEntry};
 
 use crate::error::{Error, Result};

nix-js/src/ir/utils.rs

@@ -1,3 +1,6 @@
+// Assume no parse error
+#![allow(clippy::unwrap_used)]
+
 use hashbrown::hash_map::Entry;
 use hashbrown::{HashMap, HashSet};
 use rnix::ast;

nix-js/src/lib.rs

@@ -1,3 +1,5 @@
+#![warn(clippy::unwrap_used)]
+
 mod codegen;
 pub mod context;
 pub mod error;

nix-js/src/runtime.rs

@@ -144,7 +144,7 @@ pub(crate) struct Runtime {
 }
 
 impl Runtime {
-    pub(crate) fn new(ctx: CtxPtr) -> Self {
+    pub(crate) fn new(ctx: CtxPtr) -> Result<Self> {
         // Initialize V8 once
         static INIT: Once = Once::new();
         INIT.call_once(|| {
@@ -161,14 +161,14 @@ impl Runtime {
 
         let (is_thunk_symbol, primop_metadata_symbol) = {
             deno_core::scope!(scope, &mut js_runtime);
-            Self::get_symbols(scope)
+            Self::get_symbols(scope)?
         };
 
-        Self {
+        Ok(Self {
             js_runtime,
             is_thunk_symbol,
             primop_metadata_symbol,
-        }
+        })
     }
 
     pub(crate) fn eval(&mut self, script: String) -> Result<Value> {
@@ -192,26 +192,45 @@ impl Runtime {
     }
 
     /// get (IS_THUNK, PRIMOP_METADATA)
-    fn get_symbols(scope: &ScopeRef) -> (v8::Global<v8::Symbol>, v8::Global<v8::Symbol>) {
+    fn get_symbols(scope: &ScopeRef) -> Result<(v8::Global<v8::Symbol>, v8::Global<v8::Symbol>)> {
         let global = scope.get_current_context().global(scope);
-        let nix_key = v8::String::new(scope, "Nix").unwrap();
+        let nix_key = v8::String::new(scope, "Nix")
+            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
         let nix_obj = global
             .get(scope, nix_key.into())
-            .unwrap()
+            .ok_or_else(|| Error::internal("failed to get global Nix object".into()))?
             .to_object(scope)
-            .unwrap();
+            .ok_or_else(|| {
+                Error::internal("failed to convert global Nix Value to object".into())
+            })?;
 
-        let is_thunk_sym_key = v8::String::new(scope, "IS_THUNK").unwrap();
+        let is_thunk_sym_key = v8::String::new(scope, "IS_THUNK")
-        let is_thunk_sym = nix_obj.get(scope, is_thunk_sym_key.into()).unwrap();
+            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let is_thunk = is_thunk_sym.try_cast::<v8::Symbol>().unwrap();
+        let is_thunk_sym = nix_obj
+            .get(scope, is_thunk_sym_key.into())
+            .ok_or_else(|| Error::internal("failed to get IS_THUNK Symbol".into()))?;
+        let is_thunk = is_thunk_sym.try_cast::<v8::Symbol>().map_err(|err| {
+            Error::internal(format!(
+                "failed to convert IS_THUNK Value to Symbol ({err})"
+            ))
+        })?;
         let is_thunk = v8::Global::new(scope, is_thunk);
 
-        let primop_metadata_sym_key = v8::String::new(scope, "PRIMOP_METADATA").unwrap();
+        let primop_metadata_sym_key = v8::String::new(scope, "PRIMOP_METADATA")
-        let primop_metadata_sym = nix_obj.get(scope, primop_metadata_sym_key.into()).unwrap();
+            .ok_or_else(|| Error::internal("failed to create V8 String".into()))?;
-        let primop_metadata = primop_metadata_sym.try_cast::<v8::Symbol>().unwrap();
+        let primop_metadata_sym = nix_obj
+            .get(scope, primop_metadata_sym_key.into())
+            .ok_or_else(|| Error::internal("failed to get PRIMOP_METADATA Symbol".into()))?;
+        let primop_metadata = primop_metadata_sym
+            .try_cast::<v8::Symbol>()
+            .map_err(|err| {
+                Error::internal(format!(
+                    "failed to convert PRIMOP_METADATA Value to Symbol ({err})"
+                ))
+            })?;
         let primop_metadata = v8::Global::new(scope, primop_metadata);
 
-        (is_thunk, primop_metadata)
+        Ok((is_thunk, primop_metadata))
     }
 }
 
@@ -223,14 +242,17 @@ fn to_value<'a>(
 ) -> Value {
     match () {
         _ if val.is_big_int() => {
-            let (val, lossless) = val.to_big_int(scope).unwrap().i64_value();
+            let (val, lossless) = val
+                .to_big_int(scope)
+                .expect("infallible conversion")
+                .i64_value();
             if !lossless {
                 panic!("BigInt value out of i64 range: conversion lost precision");
             }
             Value::Int(val)
         }
         _ if val.is_number() => {
-            let val = val.to_number(scope).unwrap().value();
+            let val = val.to_number(scope).expect("infallible conversion").value();
             // number is always NixFloat
             Value::Float(val)
         }
@@ -238,15 +260,15 @@ fn to_value<'a>(
         _ if val.is_false() => Value::Bool(false),
         _ if val.is_null() => Value::Null,
         _ if val.is_string() => {
-            let val = val.to_string(scope).unwrap();
+            let val = val.to_string(scope).expect("infallible conversion");
             Value::String(val.to_rust_string_lossy(scope))
         }
         _ if val.is_array() => {
-            let val = val.try_cast::<v8::Array>().unwrap();
+            let val = val.try_cast::<v8::Array>().expect("infallible conversion");
             let len = val.length();
             let list = (0..len)
                 .map(|i| {
-                    let val = val.get_index(scope, i).unwrap();
+                    let val = val.get_index(scope, i).expect("infallible index operation");
                     to_value(val, scope, is_thunk_symbol, primop_metadata_symbol)
                 })
                 .collect();
@@ -264,15 +286,17 @@ fn to_value<'a>(
                 return Value::Thunk;
             }
 
-            let val = val.to_object(scope).unwrap();
+            let val = val.to_object(scope).expect("infallible conversion");
             let keys = val
                 .get_own_property_names(scope, v8::GetPropertyNamesArgsBuilder::new().build())
-                .unwrap();
+                .expect("infallible operation");
             let len = keys.length();
             let attrs = (0..len)
                 .map(|i| {
-                    let key = keys.get_index(scope, i).unwrap();
+                    let key = keys
-                    let val = val.get(scope, key).unwrap();
+                        .get_index(scope, i)
+                        .expect("infallible index operation");
+                    let val = val.get(scope, key).expect("infallible operation");
                     let key = key.to_rust_string_lossy(scope);
                     (
                         Symbol::new(key),
@@ -291,7 +315,7 @@ fn is_thunk<'a>(val: LocalValue<'a>, scope: &ScopeRef<'a, '_>, symbol: LocalSymb
         return false;
     }
 
-    let obj = val.to_object(scope).unwrap();
+    let obj = val.to_object(scope).expect("infallible conversion");
     matches!(obj.get(scope, symbol.into()), Some(v) if v.is_true())
 }
 
@@ -304,7 +328,7 @@ fn to_primop<'a>(
         return None;
     }
 
-    let obj = val.to_object(scope).unwrap();
+    let obj = val.to_object(scope).expect("infallible conversion");
     let metadata = obj.get(scope, symbol.into())?.to_object(scope)?;
 
     let name_key = v8::String::new(scope, "name")?;
@@ -324,13 +348,14 @@ fn to_primop<'a>(
 }
 
 #[cfg(test)]
+#[allow(clippy::unwrap_used)]
 mod test {
     use super::*;
     use crate::context::Context;
 
     #[test]
     fn to_value_working() {
-        let mut ctx = Context::new();
+        let mut ctx = Context::new().unwrap();
         assert_eq!(
             ctx.eval_js(
                 "({

nix-js/src/value.rs

@@ -39,8 +39,9 @@ impl Display for Symbol {
     }
 }
 
-static REGEX: LazyLock<Regex> =
+static REGEX: LazyLock<Regex> = LazyLock::new(|| {
-    LazyLock::new(|| Regex::new(r"^[a-zA-Z_][a-zA-Z0-9_'-]*$").unwrap());
+    Regex::new(r"^[a-zA-Z_][a-zA-Z0-9_'-]*$").expect("hardcoded regex is always valid")
+});
 impl Symbol {
     /// Checks if the symbol is a "normal" identifier that doesn't require quotes.
     fn normal(&self) -> bool {