Go Commentary #14: Golang compile-time evaluation and Go bindings to SQLite using wazero

Prep: Golang comptime. Pure blasphemy

• A small Go tool that enables compile-time function evaluation. By using prep.Comptime, you can evaluate functions at build time, replacing them with their computed results. Just like comptime from Zig. Except it’s not.

• Features

  • Compile-Time Evaluation: Replace function calls with their computed results at build time.
  • Simple Integration: Use prep as both a Go library and a standalone executable.
  • Tooling Support: Easily integrate prep with your Go build process using -toolexec.

package main

import (
  "fmt"
  "github.com/pijng/prep"
)

func main() {
  // This will be evaluated at compile-time
  result := prep.Comptime(fibonacci(300))

  fmt.Println("Result:", result)
}

func fibonacci(n int) int {
  fmt.Printf("calculating fibonacci for %d\n", n)

  if n <= 1 {
    return n
  }

  return fibonacci(n-1) + fibonacci(n-2)
}

• Build go build -a -toolexec="prep <absolute/path/to/project>" main.go

• Limitations

  • Currently, prep.Comptime only supports basic literals as arguments.

  // Pass a basic literal directly
  func job() {
    prep.Comptime(myFunc(1))
  }
  
  // Use a variable with the value of basic literal from the same scope as wrapped function
  func job() {
    x := 1
    y := 2
    prep.Comptime(myFunc(x, y))
  }
  

  • Only functions that can be fully resolved with the provided literal arguments can be evaluated at compile-time, therefore it is impossible to use any values from IO operations.

go-sqlite3: Go bindings to SQLite using wazero

• Go module github.com/ncruces/go-sqlite3 is a cgo-free SQLite wrapper. It provides a database/sql compatible driver, as well as direct access to most of the C SQLite API.

• It wraps a Wasm build of SQLite, and uses wazero as the runtime. Go, wazero and x/sys are the only runtime dependencies.

import "database/sql"
import _ "github.com/ncruces/go-sqlite3/driver"
import _ "github.com/ncruces/go-sqlite3/embed"

var version string
db, _ := sql.Open("sqlite3", "file:demo.db")
db.QueryRow(`SELECT sqlite_version()`).Scan(&version)

https://github.com/pijng/prep

https://github.com/ncruces/go-sqlite3

https://github.com/tetratelabs/wazero