Use no-std-compat to build no-std.

src/module/resolvers/collection.rs

@@ -1,5 +1,7 @@
-use crate::stdlib::{boxed::Box, ops::AddAssign, vec::Vec};
 use crate::{Engine, EvalAltResult, Module, ModuleResolver, Position, Shared};
+use std::ops::AddAssign;
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
 
 /// [Module] resolution service that holds a collection of module resolvers,
 /// to be searched in sequential order.

src/module/resolvers/dummy.rs

@@ -1,5 +1,6 @@
-use crate::stdlib::boxed::Box;
 use crate::{Engine, EvalAltResult, Module, ModuleResolver, Position, Shared};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
 
 /// Empty/disabled [module][Module] resolution service that acts as a dummy.
 ///

src/module/resolvers/file.rs

@@ -1,10 +1,11 @@
-use crate::stdlib::{
-    boxed::Box,
+use crate::{Engine, EvalAltResult, Identifier, Module, ModuleResolver, Position, Shared};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+use std::{
     collections::BTreeMap,
     io::Error as IoError,
     path::{Path, PathBuf},
 };
-use crate::{Engine, EvalAltResult, Identifier, Module, ModuleResolver, Position, Shared};
 
 pub const RHAI_SCRIPT_EXTENSION: &str = "rhai";
 
@@ -45,9 +46,9 @@ pub struct FileModuleResolver {
     cache_enabled: bool,
 
     #[cfg(not(feature = "sync"))]
-    cache: crate::stdlib::cell::RefCell<BTreeMap<PathBuf, Shared<Module>>>,
+    cache: std::cell::RefCell<BTreeMap<PathBuf, Shared<Module>>>,
     #[cfg(feature = "sync")]
-    cache: crate::stdlib::sync::RwLock<BTreeMap<PathBuf, Shared<Module>>>,
+    cache: std::sync::RwLock<BTreeMap<PathBuf, Shared<Module>>>,
 }
 
 impl Default for FileModuleResolver {

src/module/resolvers/mod.rs

@@ -1,6 +1,7 @@
 use crate::fn_native::SendSync;
-use crate::stdlib::boxed::Box;
 use crate::{Engine, EvalAltResult, Module, Position, Shared, AST};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
 
 mod dummy;
 pub use dummy::DummyModuleResolver;

src/module/resolvers/stat.rs

@@ -1,5 +1,7 @@
-use crate::stdlib::{boxed::Box, collections::BTreeMap, ops::AddAssign};
 use crate::{Engine, EvalAltResult, Identifier, Module, ModuleResolver, Position, Shared};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+use std::{collections::BTreeMap, ops::AddAssign};
 
 /// A static [module][Module] resolution service that serves [modules][Module] added into it.
 ///