I built a programming language where you can't lose a cent: a 5-minute tour of Quill

Description and use

Quill is a programming language that guarantees precise monetary calculations and explicit failure handling, preventing loss of cents and silent bugs.

Problem

Developers need a language that enforces clear intent, explicit failures, and correctness, especially for financial calculations and error handling.

Outcome

Quill provides a concise, type‑safe syntax for business logic, ensuring monetary calculations never lose a cent and that all failure paths are explicitly handled.

Workflow

• Install Quill via curl installer
• Create a new app with quill new shop app
• Run the server with quill run server.quill
• Write data queries using natural‑language‑style syntax
• Perform money splits with say split 100 USD into 3
• Use explicit currency conversion with convert 20 EUR to USD at 0.92
• Define functions with typed failures, e.g., fn charge(amount: USD) -> text
• Handle failures with on Declined -> "declined"
• Run tests with quill test

Evidence

Quill is an open-source language for backends, business software and automation.

Source

say split 100 USD into 3 -- 33.34 USD, 33.33 USD, 33.33 USD

Source

100 USD + 20 EUR doesn't run. Quill says it won't mix currencies, and suggests convert 20 EUR to USD at 0.92

Source