Your First Program

Hello World

Create a file called hello.fl:

export fn greet(name: string) -> string {
  `Hello, ${name}!`
}

greet("world") |> Console.log

Compile it:

floe build hello.fl

This produces hello.ts:

export function greet(name: string): string {
  return `Hello, ${name}!`;
}

console.log(greet("world"));

A React Component

Create counter.fl:

import { useState } from "react"

export fn Counter() -> JSX.Element {
  const [count, setCount] = useState(0)

  <div>
    <p>Count: {count}</p>
    <button onClick={fn() setCount(count + 1)}>+1</button>
  </div>
}

Compile it:

floe build counter.fl

This produces counter.tsx, a standard React component that works with any React setup.

Using Pipes

Pipes let you read transformations left-to-right instead of inside-out:

// Without pipes (nested calls)
const result = toString(add(multiply(value, 2), 1))

// With pipes (left to right)
const result = value
  |> multiply(2)
  |> add(1)
  |> toString

By default, the piped value is inserted as the first argument. Use _ when you need it in a different position: value |> f(other, _) becomes f(other, value).

Type Checking

Run the type checker without generating output:

floe check src/

This catches errors like:

• Using any (use unknown instead)
• Nullable values without Option<T>
• Non-exhaustive pattern matches
• Unused variables and imports