---
title: "WASM Procedures: Quick Start"
---

# WASM Procedures: Quick Start

**Part of**: [WASM Procedures User Guide](https://www.heliosdb.com/docs/full/guides/features/wasm_procedures_user_guide/)

:::caution[Not yet available in the server]
The current `heliosdb-full` server does not run WASM procedures. "WASM
functions" are on its list of subsystems that are not wired, so SQL that
would create or call a WASM procedure fails with SQLSTATE `0A000`. You can
already write, build and unit-test Go procedures with the SDK below, and they
target the WASM host included in the HeliosDB Full source. Steps 4 and 5
show how procedures will be deployed once the server enables that host.
:::

---

**Time required: 15 minutes**

## Language support

| Language | Published SDK | Status |
|----------|---------------|--------|
| Go (TinyGo) | [`github.com/HeliosDatabase/HeliosDB-SDKs/sdks/go/wasm`](https://github.com/HeliosDatabase/HeliosDB-SDKs/tree/main/sdks/go/wasm) | Available. Builds modules for Full's WASM host ABI, and includes a fake host for `go test`. |
| Rust | None | No SDK crate is published. The `heliosdb-sdk` crate named in older pages does not exist. |
| JavaScript / AssemblyScript | None | No npm package is published. `@heliosdb/wasm-sdk` does not exist. |
| Python | None | No PyPI package is published. `heliosdb-wasm-sdk` does not exist. |

Any language that compiles to a core WebAssembly module could import the same
host functions directly. See [Host Functions](https://www.heliosdb.com/docs/full/guides/features/wasm_procedures_host_functions/).

## Step 1: Install the tools

- Go 1.21 or newer: <https://go.dev/dl/>
- TinyGo 0.34 or newer: <https://tinygo.org/getting-started/install/>

## Step 2: Create a module

```bash
mkdir my-procedure && cd my-procedure
go mod init example.com/my-procedure
go get github.com/HeliosDatabase/HeliosDB-SDKs/sdks/go/wasm@latest
```

## Step 3: Write and test a procedure

`main.go`:
```go
package main

import "github.com/HeliosDatabase/HeliosDB-SDKs/sdks/go/wasm/heliosdb"

// Procedures take and return WASM scalars, so the tier is passed as a
// number here: 1 = gold, 2 = silver, 3 = bronze.
//
//export calculate_discount
func calculateDiscount(orderTotal float64, customerTier int32) float64 {
    rate := 0.0
    switch customerTier {
    case 1:
        rate = 0.15
    case 2:
        rate = 0.10
    case 3:
        rate = 0.05
    }
    heliosdb.LogInfo("calculate_discount: tier rate applied")
    return orderTotal * rate
}

// Required by the Go toolchain; the host calls the exported function directly.
func main() {}
```

`main_test.go`:
```go
package main

import (
    "testing"

    "github.com/HeliosDatabase/HeliosDB-SDKs/sdks/go/wasm/heliosdbtest"
)

func TestCalculateDiscount(t *testing.T) {
    fake := heliosdbtest.Install(t)
    if got := calculateDiscount(1000, 1); got != 150 {
        t.Fatalf("got %v", got)
    }
    if len(fake.Logs) != 1 {
        t.Fatalf("logs = %v", fake.Logs)
    }
}
```

```bash
go test ./...
```

## Step 4: Build the WASM module

```bash
tinygo build -target=wasm-unknown -gc=conservative -opt=z -no-debug -o procedure.wasm .
```

- Use `-target=wasm-unknown`. The host links only its own `env` functions and
  no WASI, so a `-target=wasip1` module fails to instantiate.
- Export procedures with `//export`. The host calls exported functions
  directly and never runs `_start` or `_initialize`, which modules built with
  the standard Go toolchain need.

The [SDK README](https://github.com/HeliosDatabase/HeliosDB-SDKs/tree/main/sdks/go/wasm)
has the full API, a tested example, and an ABI conformance suite that checks
the module against Full's host.

## Step 5: Deploy (once the server enables WASM procedures)

The SQL surface for registering a module is shown below for reference. With
the current server, these statements fail with SQLSTATE `0A000`.

```sql
-- Planned syntax for the upcoming WASM procedures feature; the current server does not accept it.
CREATE PROCEDURE calculate_discount(order_total DOUBLE PRECISION, customer_tier INTEGER)
RETURNS DOUBLE PRECISION
LANGUAGE wasm
AS '/path/to/procedure.wasm';

SELECT calculate_discount(1000.0, 1);  -- 150
```

---

**Navigation:**
- **Previous**: [Introduction](https://www.heliosdb.com/docs/full/guides/features/wasm_procedures_intro/)
- **Next**: [Language SDKs](https://www.heliosdb.com/docs/full/guides/features/wasm_procedures_language_sdks/)
- **Index**: [WASM Procedures User Guide](https://www.heliosdb.com/docs/full/guides/features/wasm_procedures_user_guide/)