# I Built a Self-Hosting Language, a DB Engine and a Microkernel — Entirely on My Phone

> Source: <https://dev.to/sayan9168/i-built-a-self-hosting-language-a-db-engine-and-a-microkernel-entirely-on-my-phone-2edc>
> Published: 2026-08-30 10:17:41+00:00

No laptop. No IDE. Just Termux and a text editor.

Over the past year I shipped five systems from my Android phone:

Here's how the core works.

The pipeline is classic:

source → tokenizer → recursive-descent parser → AST

→ tree-walk interpreter

→ bytecode compiler → stack VM

→ C / WAT transpilers

The bytecode compiler emits a flat instruction list. This is real output

from `sahajcore --compile`

:

```
0004 LOAD a
0005 LOAD b
0006 CONST 2
0007 BIN *
0008 BIN +
0009 STORE c
0014 BIN >
0015 JZ 19
```

The interpreter is written in SahajCore itself. The bootstrap chain:

Python-hosted interpreter

→ runs selfhost.sahaj (interpreter written in SahajCore)

→ runs target.sahaj (user program)

The hardest bug: recursive Fibonacci blew the Python stack because every

target-level call expanded into hundreds of host frames. Fix: rewrote the

demo iteratively and raised the recursion limit.

A tiny relational engine with:

```
pip install sahajcore
pip install sahajql
```

GitHub: github.com/sayan9168/SahajCore

Happy to go deep on any part — ask me anything.