no-std bin+lib netsblox-vm

A crate for running NetsBlox code with optional native extensions

10 releases

new 0.2.8 Sep 21, 2023
0.2.7 Sep 15, 2023
0.2.5 Aug 2, 2023
0.2.3 Jul 26, 2023
0.1.0 Nov 20, 2022

#37 in Emulators

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95 downloads per month


10K SLoC


NetsBlox is a browser-based visual programming environment (based on Snap!) that extends the typical block-based programming features with internet and distributed computing tools such as RPCs (remote procedure calls) that access network resources (e.g., databases or web APIs), and message passing between projects over the internet.

netsblox-vm is a native Rust implementation of the NetsBlox code execution engine and runtime. This makes it possible to execute NetsBlox program code at blistering speeds on any device targeted by the Rust compiler. But more importantly, netsblox-vm has several extension APIs which make it possible to extend its features with new hardware peripheral access capabilities (e.g., controlling sensors and actuators through GPIO), all with safe, native Rust.


netsblox-vm contains the following feature flags.

name default description
std on Enables the std crate dependency and access to the default StdSystem implementation of System
cli on Enables the std feature flag and additionally gives access to the cli submodule, which gives API access to the standard CLI (needed for syscall extensions) rather than having to write a CLI from scratch
serde on Enables serialization of some types
native-tls on Enables the native-tls feature for TLS-capable dependencies (only used if std is also enabled)
native-tls-vendored off Enables the native-tls-vendored feature for TLS-capable dependencies (only used if std is also enabled)
rustls-tls-native-roots off Enables the rustls-tls-native-roots feature for TLS-capable dependencies (only used if std is also enabled)
rustls-tls-webpki-roots off Enables the rustls-tls-webpki-roots feature for TLS-capable dependencies (only used if std is also enabled)

Note that if std is enabled, one of the TLS feature flags must also be enabled in order to connect to the NetsBlox server with StdSystem. The native-tls feature is enabled by default to support this on common desktop and server environments; however you may need to disable default features and explicitly opt into a different TLS option for other targets (e.g., Android or iOS).


netsblox-vm supports building in no-std environments by disabling the default std feature flag. However, the alloc crate is still required in this case.

netsblox_vm = { version = "...", default-features = false }

Note that this precludes access to StdSystem, meaning a new implementation of System would be required for your target platform.

CLI Installation

This crate includes a binary called nb which serves as a shallow wrapper for the cli API with a default suite of syscall extensions. Note: if you need to create your own syscall extensions, you must do so in a separate binary using this crate as a dependency.

cargo install netsblox-vm


~348K SLoC