peach

A statically typed functional language.

fib =
  (0) => 1,
  (1) => 1,
  (x) => fib(x - 1) + fib(x - 2)

map(fib, [0 1 2 3 4 5 6 7 8 9 10])
# [ 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89 ]

Syntax

Peach is inspired by JavaScript, Elm, Clojure and @bodil's BODOL, which I learned about from this awesome talk.

# assignment
x = 2 # 2

# equality
x == 2 # true

# maths and stuff
x * 2 # 4

# conditionals
if (x < 10)
  `little`
else if (x < 20)
  `medium`
else
  `large`

# functions
double = x => x * 2
map(x => (pow x 2), [1, 2, 3, 4]) # [2 4 8 16]

# currying
double-all = map(double)
double-all([1 2 3 4]) # (2 4 6 8)

# pattern matching
fib =
  (0) => 1,
  (1) => 1,
  (x) => fib(x - 1) + fib(x - 2

starts-with-one =
  ([1|_]) => true,
  _  => false

# tail call optimisation
# n: the accumulating factorial
# x: a decrementing iteration count
factorial =
  (n, 1) => n,
  (n, x) => factorial((n * x), (x - 1))

factorial(1, 32768) # Infinity, because JavaScript. Better than a stack overflow!

Semantics

• Static typing (with Damas-Hindley-Milner type inference)
• Pure functions
• Everything is an expression
• Immutability
• Strict evaluation
• Currying

Features

• Minimal syntax
• A tree-based JavaScript interpreter
• REPL
• Proper tails calls

Plans

Coming soon:

• Type hint syntax
• More stdlib
• Algebraic data types

And then:

• JavaScript interop
• JavaScript code generation
• Lazy sequences
• IO

One day:

• Efficient bytecode interpreter
• Interactive debugger
• Immutable data structures with structural sharing
• Self-hosting

Develop

Use Node 6+.

npm install
npm test