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Getting Started with NumFu

NumFu is a pure, interpreted, functional programming language designed for readable and expressive code, extensibility, and ease of learning for beginners.

NumFu's simple syntax and semantics make it well-suited for educational applications, such as courses in functional programming and general programming introductions. At the same time, as its name suggests, NumFu is also ideal for exploring mathematical ideas and sketching algorithms, thanks to its native support for arbitrary-precision arithmetic.

  • Expressive syntax: Infix operators a + b, spread/rest operator ... and easy testing ---> $ == 42
  • Arbitrary precision arithmetic for reliable mathematical computing
  • First-class functions with automatic partial application
  • Tail call optimization for efficient recursive algorithms without stack overflow
  • Interactive development with a friendly REPL and helpful errors
  • Large standard library provided by NumFu's python bindings
  • Minimal complexity by only having four types: Number, Boolean, List and String

Quick Example​

Here's a taste of what NumFu looks like:

// Mathematical computing
let goldenRatio = {depth ->
  let cf = {d ->
    if d <= 0 then 1
    else 1 + 1 / cf(d - 1)
  } in cf(depth)
} in goldenRatio(10)
// 1.61797752808989

// Function composition & piping
let add1 = {x -> x + 1},
    double = {x -> x * 2} in
let composed = add1 >> double in
  5 |> composed; // 12

// Native partial application
{x, y, z -> x + y + z}(_, 2)
// {x, z -> x+2+z}

// Built-in testing with assertions
let square = {x -> x * x} in
  square(5) ---> $ == 25; // ✓ passes

Installation​

From PyPI​

# make sure you have Python >= 3.10 installed
pip install numfu-lang

From Source​

git clone https://github.com/rphle/numfu
cd numfu
make install

Your First NumFu Program​

Create a file called hello.nfu:

// hello.nfu
import println from "io"
import format from "std"

println("Hello, NumFu!")

// Let's do some math
let fibonacci = {n ->
  if n <= 1 then n
  else fibonacci(n - 1) + fibonacci(n - 2)
}

println(format("The 10th Fibonacci number is: {}", fibonacci(10)))

// Test our function
fibonacci(5) ---> $ == 5

Run it:

numfu hello.nfu

Interactive Development​

Start the REPL for interactive exploration:

numfu repl
NumFu REPL. Type 'exit' or press Ctrl+D to exit.
>>> 2 + 3 * 4
14
>>> let square = {x -> x * x} in square(7)
49
>>> import max from "math"
>>> [1, 2, 3, 4, 5, 6, 7] |> filter(_, {x -> x%2 == 0}) |> max
6

What's Next?​