pow […!!… (iterate (…⋅… 0) (+1))]

…**… pow

:test ((+2) ** (+3) =? (+8)) (true)

Functional language based on pure bruijn-indexed lambda calculus.

Hint: Click on anything you don't understand.

Lambdas all the way down.
No primitive functions.

> (+5)
[[[[2 (2 (1 3))]]]]
> 'a'
[[[1 (0 (0 (0 (0 (1 (1 (0 2)))))))]]]
> add
[[(([([[1 0 [[0]]]] ((((0 [[(((0...

> :time factorial (+30)
0.15 seconds

Efficient call-by-need reduction using abstract machines.

Substantial standard library.
Docs

> ∏ (+1) → (+3) | ++‣
> number! <$> (lines "42\n25")
> sum (take (+3) (repeat (+4)))
> (+10b) ⋀! (+12b)

$ echo "main [0]" > echo.bruijn
$ bruijn -b echo.bruijn > echo
$ wc -c echo
2 echo
$ echo "hello world!" | bruijn -e echo
hello world!

Compilation to Tromp's binary lambda calculus.
Support for byte and ASCII encoding.

Learn more: GitHub

Installation

$ git clone https://github.com/marvinborner/bruijn.git && cd bruijn
$ stack run # for playing around
$ stack install
$ bruijn

Broogle

$ ./broogle.sh -f add
add ⧗ Unary → Unary → Unary
also known as …+…
in std/Number/Unary.bruijn:35
# adds two unary numbers
...

Learn more: GitHub

Compiled binary lambda calculus is incredibly expressive and tiny. Read the articles by Justine and Tromp.
Exploring different encodings of data as function abstractions is fascinating.
Pure lambda calculus can be very beautiful. You will understand if you try to have some fun with it.
I don't like naming parameters of functions. Using bruijn indices is a universal reference independent of the function and can actually help readability if you're familiar enough.
Really, just for fun.

Standard library: Docs