JamScript

Build JAM services with a TypeScript-like developer experience.

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JamScript hides the low-level JAM/PVM plumbing behind a small language, a deterministic build pipeline, and the jams CLI. You write services; JamScript handles the compiler toolchain, PVM artifacts, deployment flow, and local backend.

⚡ Install

curl -fsSL https://install.minijam.xyz/jamscript | bash

The installer automatically selects the latest published JamScript release and installs:

• jams — the JamScript CLI
• the managed compiler/toolchain
• the matching native jamscript-service-backend

Supported today: Linux x86_64 and macOS Apple Silicon.

To pin an exact release:

curl -fsSL https://install.minijam.xyz/jamscript \
  | bash -s -- --version v0.1.0-rc.8

🧩 Example

import { action, wallet, u64 } from "jam";

export const increment = action({
  auth: wallet(),
  input: { value: u64 },
  execute(ctx, input) {
    return input.value + 1;
  },
});

Build and deploy:

jams build
jams deploy --network local

Run the local backend when the application needs it:

jams backend start --network local

For a configured testnet profile, select it at the CLI layer:

jams backend start --network testnet

The CLI resolves the named profile and passes concrete Node and Formal RPC endpoints to the backend. The backend process itself is network-name agnostic.

✨ What JamScript handles

• deterministic JamScript → PVM builds
• managed compiler and toolchain installation
• JAM-compatible typed ABI and managed state
• Ownership-based authorization
• MiniJAM deployment
• local backend lifecycle through the jams CLI

You do not need to work directly with Refine/Accumulate internals for normal application development.

📚 Documentation

For guides, architecture, language details, deployment, and examples:

JamScript Documentation →

⚠️ Limitations

JamScript v0.1 is currently an RC/testnet developer preview.

• The current implementation builds on the mature PolkaVM toolchain. This gives JamScript a reliable execution foundation, but also introduces efficiency overhead that we intend to reduce as the toolchain becomes more JamScript-specific.
• In the current ScriptC execution path, ordinary numeric computation still uses floating-point number representation by default in some paths. Fixed-width ABI types such as u64 and u128 remain explicit at service boundaries, but the internal numeric lowering is not yet fully optimized. This will be improved before the stable release.
• Windows is not supported in the current release.
• Generic JAM mainnet deployment remains future work.

📄 License

Apache-2.0