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sarina-lang

A Custom Language

This is a custom toy language that I put together as an exercise. The interpreter uses a recursive descent parser and runs in Node.js.

The language is entirely contained in interpreter.js. You can interpret a file by running something like this: node interpreter.js path/to/file.s

Syntax

The only construct the language supports is the function call. It uses postfix notation. Arguments are sandwiched between : and ; . If a function can take multiple arguments they are separated with a ,.

example

this:

: 'Hello, World!' ; print

writes this to standard out:

Hello, World!

Types

Since I wrote the interpreter in JavaScript, the language inherits the little typing it has from JavaScript. Admittedly, the typing is next to non-existant, but the laguage has at least these three types: 'number', 'string', and 'function'. I also added a 'list' type, which is a little one off. The list type is represented internally as a JavaScript array. These types are enforced through cryptic runtime error messages emanating from the interpreter's JavaScript internals.

Buzzwords

  • Functional
  • Curried Functions
  • Functional Composition
  • First Class functions
  • Reverse Polish Notation
  • Has cons
  • Side effect free, not used in production anywhere.
  • Gluten free*

Functions included in the standard library:

  • + - Adds two numbers - binary, curried
  • * - Multplies two numbers - binary, curried
  • / - (interger) Divides two numbers - binary, curried
  • - - Subtracts two numbers - binary, curried
  • % - Mods two numbers - binary, curried
  • = - Tests if two numbers are equal. Returns 1 if they are else returns 0. - binary, curried
  • print - Prints one arg - unary
  • compose - Composes two functions - binary, uncurried
  • concat - Contactenates two args that it converts to strings - binary, curried
  • cons - Pass an item to return a list. Pass a list and call the resulting function with an item to add it to the list - binary or unary, curried
  • wrap - Takes the function to wrap and the list of args. Use cons to build the list. binary, curried
  • if - 0 counts as false, everything else counts as true. if function takes function called on true, function called on false, number to test. Use wrap to create the "true" and "false" functions. - ternary, curried
  • list - Cheaters way to make a list. Takes unlimited arguments. Returns its arguments as a list. - ?multinary, uncurried
  • range - creates a list of numbers within a given range between the two arguments. - binary, curried
  • reduce - iterates through a list accumulating a result. First argument is a function that takes the previous (accumulator) element, and the current element to iterate. Second argument is the list to reduce - binary, curried
  • map - iterates through a list and returns a new list where the elements are transformed by a function. map's first argument is the function to do the transformation (which is called on each element), and the second argument is the list to map over - binary, curried

Getting started

Clone the repo and then run:

npm install

After that you can run programs like this: node interpreter.js path/to/file.s

Running examples

Examples are stored under examples you can run the hello world example like this:

node interpreter.js examples/01_hello_world.s

List of examples:

  1. examples/01_hello_world.s
  2. examples/02_add_and_concat.s
  3. examples/03_math.s
  4. examples/04_compose.s
  5. examples/05_cons.s
  6. examples/06_wrap.s
  7. examples/07_if.s
  8. examples/08_list.s

* Tests below FDA maximum threshold of 20ppm for gluten free labeling.