JavaScript to Rust. Three Commands. Done.

The Problem with Language Migration

You have a JavaScript function. It works. Your team has decided to move to Rust. What are your options today?

Option A: Rewrite it by hand. Spend a week. Hope you got the edge cases right. Write all new tests. Debug for another week. Pray.

Option B: Ask an AI to translate it. Get something that looks right. Ship it. Discover a subtle integer overflow bug in production three months later. Explain to your CTO what happened.

Option C: Three commands. Verified. With tests. Done.

brikc lift utils.js        # 1. Convert to verified blueprint
brikc check utils.pcd      # 2. Verify the blueprint
brikc build utils.pcd \
  --target rust             # 3. Export to Rust + tests

Let me show you exactly how this works.

Step 1: Lift

You have this JavaScript:

// utils.js
function fibonacci(n) {
  if (n <= 1) return n;
  let a = 0, b = 1;
  for (let i = 2; i <= n; i++) {
    let temp = a + b;
    a = b;
    b = temp;
  }
  return b;
}

function clamp(value, min, max) {
  if (value < min) return min;
  if (value > max) return max;
  return value;
}

function gcd(a, b) {
  while (b !== 0) {
    let temp = b;
    b = a % b;
    a = temp;
  }
  return a;
}

Run the Lifter:

$ brikc lift utils.js

⚡ Lifting utils.js (JavaScript)...

Summary: 3/3 functions liftable
Overall score: 100%

  ✓ LIFTABLE fibonacci — 100%
  ✓ LIFTABLE clamp     — 100%
  ✓ LIFTABLE gcd       — 100%

3 circuits lifted

Three for three. All pure functions — no side effects, completely deterministic. The Lifter converts them to PCD blueprints automatically. Zero manual work. Zero configuration.

Step 2: Check

Now here is the part that changes everything. Verify that the blueprints are mathematically correct:

$ brikc check fibonacci.pcd
  ✓ fibonacci: verified (0.001s)

$ brikc check clamp.pcd
  ✓ clamp: verified (0.001s)

$ brikc check gcd.pcd
  ✓ gcd: verified (0.001s)

Each blueprint is now mathematically certified. The logic is correct for every possible input — not "tested against some cases," not "probably right." Proven. For all cases. Every input. Every edge case. Every combination. Done.

Step 3: Build

Now, the moment you have been waiting for. Export to Rust:

$ brikc build fibonacci.pcd --target rust
  ✓ Generated: fibonacci.rs
  ✓ Generated: fibonacci_test.rs (6 test cases)

$ brikc build clamp.pcd --target rust
  ✓ Generated: clamp.rs
  ✓ Generated: clamp_test.rs (8 test cases)

$ brikc build gcd.pcd --target rust
  ✓ Generated: gcd.rs
  ✓ Generated: gcd_test.rs (5 test cases)

You now have idiomatic, production-ready Rust — with auto-generated tests included. This is not a line-by-line translation. The code is generated from the verified blueprint, following Rust conventions, with Rust idioms, with Rust safety. And every single test is derived from the mathematical certification.

But wait — what about the other direction?

But here is what makes this truly revolutionary. That same blueprint — the same verified truth — can export to any language:

# To Python
$ brikc build fibonacci.pcd --target python
  ✓ fibonacci.py + test_fibonacci.py

# To JavaScript (yes, back to JS — but now with generated tests)
$ brikc build fibonacci.pcd --target javascript
  ✓ fibonacci.js + fibonacci.test.js

# To WebAssembly
$ brikc build fibonacci.pcd --target wasm32
  ✓ fibonacci.wasm

# To native binary
$ brikc build fibonacci.pcd --target native
  ✓ fibonacci (x86-64 ELF)

One blueprint. Five outputs. All verified. All with tests. Same behavior, guaranteed, across every single target. That is not translation. That is generation from truth.

Why this is better than AI translation

When an AI translates JavaScript to Rust, it is guessing. Sophisticated guessing, sure — pattern matching at scale. "This JS pattern usually maps to this Rust pattern." And it works most of the time. But "most of the time" is exactly the problem when you are shipping financial software, medical devices, or anything where correctness actually matters.

When BRIK64 exports from a PCD blueprint:

1. The logic is verified — mathematically proven correct for all inputs. 2. The target code is generated from that verified specification — not translated, generated. 3. The tests are derived from the certification, not guessed by a developer. 4. Every export produces identical behavior — JavaScript, Rust, Python, Go, C — all implement the exact same verified blueprint. Bit for bit.

This is not translation. This is generation from a proven specification. And that difference? That is the difference between "it probably works" and "it is mathematically guaranteed to work."

The complete migration workflow

1. brikc lift legacy-app/src/ --format json
   → See which functions are migratable (usually 60-80%)

2. Review the liftability report
   → Pure functions: ready to migrate
   → Impure functions: need architectural decisions

3. brikc build *.pcd --target rust
   → Generate Rust code + tests for all liftable functions

4. Push to new GitHub repo
   → Certified, tested, ready for production

Getting started

# Install
curl -fsSL https://brik64.dev/install | sh

# Try it on your code
brikc lift your-file.js

# Export to your target language
brikc build your-function.pcd --target rust

Three commands. Verified migration. Tests included. Welcome to the future of language migration.