Pipple

Pipple is a simple Lisp-family programming language.

Getting started

Pipple builds with CMake. Run the following to build Pipple:

cmake -B build -DCMAKE_BUILD_TYPE=Release
cmake --build build

The pipple executable will be placed in the build folder.

Coding with Pipple

Pipple's interpreter provides a REPL for fast prototyping. Try it out by running the pipple command without any arguments.

$ ./build/pipple
pipple>

Pipple code you write will be run now. Try something like (print "Hello, World!"). See what happens!

If you'd like to use Pipple with a file, just add the filename after the executable path, like pipple path/to/code.ppl

Pipple also has an experimental transpiler, which will turn your Pipple code into C++. To use, run pipple -c path/to/code.ppl. This will print code to the console.

To quickly compile Pipple code, try pipple -c path/to/code.ppl | g++ -xc++ - -o exename, where exename is the name of the executable to output to.

Syntax

Pipple's syntax looks like most other Lisps. You enclose your statements in ( and ).

Printing

(print "Hello, World!")
(print 32)
(print 3.141)

Setting and Changing Variables

let initializes a variable for the first time.

set changes that variable to something else.

Note: set is currently unsupported by the Pipple transpiler.

(let x 3.141)
(print x)
(set x 2.712)
(print x)

Math

Remember: Polish notation is the key!

Note: All math is currently unsupported by the Pipple transpiler.

(let x (+ 3 4))
(print x)

(let y (* 5 6 2))
(print y)

(print (/ 10 2))

(print (- 10 5))

Conditionals

In Pipple, nil is the only non-truthy value. Every non-nil value is truthy.

Note: All conditionals are currently unsupported by the Pipple transpiler.

(let x 0)
(if (== x 0)
    (print "x is zero")
    (set x 1)
    (print "now it is" x)
)

(while (!= x 5)
    (print "x is currently" x "which is not 5. i must make it 5")
    (set x (+ x 1))
)
(print "now x is" x)

User console input

Note: input is currently unsupported by the Pipple transpiler.

(let x (input))
(print "You said" x)

Lists

Note: Lists are currently unsupported by the Pipple transpiler.

(list item1 item2 item3)
(list "hi there" 32 nil)

Functions

Pipple functions require type annotations. They are also first class.

Functions are defined with the following syntax:

(function returntype [argtype argname argtype argname] (code) (morecode))

(let x (function int [int x]
    (return (* x 5))
))

(print (x 3))

Valid types in Pipple are:

• int
• double
• string
• list (Currently unsupported by the Pipple transpiler)