is is an experimental simplified language that is transpiled to JavaScript. The aim is to create a language for scripting that does not require any significantly complex symbols or constructs, so that it can be used by more novice programmers to achieve simple tasks.

• Usage
• Run Tests
• Language Manual
• Examples

1. Write a .is input file in the is language (see below).
2. Run npm run compile $INPUT_FILE to transpile to JavaScript.
3. Run the output build.js as usual using node.

For example, the example test file example.is:

$ npm run compile ./example.is

$ node build.js

Optionally, specify --show-source to see each output line's input included as a comment.

$ npm test

The is language follows a similar structure to most other statement-based languages. The basic concepts are demonstrated below.

Note: At the moment, only one operation per line is supported.

Comments are signified using // at the start of a line.

// This is a comment!

Variables are declared using the value keyword, and an initial value.

value my_value is 0

value my_value is 25 + 100

Variables are reassigned using the is keyword.

my_value is 10

my_value is 'hello' + 'world'

Use the log keyword to output strings, optionally including variables with a template.

value my_value is 10

log 'Your value is now {my_value}'

Functions are declared using the task keyword and ended with the end keyword. Function parameters must always be declared after gets, or nothing if there are no parameters.

task increment gets input_value
  return input_value + 1
end

Functions are called using the run keyword, specifying arguments after with.

task greet gets name
  log 'Hello there, {name}!'
end

value name is 'Chris'
run greet with name

You can use the return value of a function by combining is with run (and optionally with):

value result is run fibonacci with 9

An 'if' style statement can be used with when and any standard operators. As with functions, the end keyword tells is when the 'if' is finished.

when temperature > 28
  log 'Too hot!'
end

The until keyword allows a 'while' style loop to run until the value indicated by equals is reached. As with functions, the end keyword tells is when the loop is finished.

value counter is 0
value maximum is 100

until counter equals maximum
  run increment with counter
  log '{counter}'
end

Objects can contain more than one value, and so are declared differently to plain values with the object keyword, then followed up with property statements to add properties.

object car
car property num_wheels is 4
car property color is 'red'

Object values are accesses simply using the . operator.

log 'Car has {car.wheels} wheels'

value car_color is car.color

Specific imports are available (such as fetch for web requests) by using the using keyword.

using fetch

Using an unrecognised library will throw an error detailing which libraries are available to use.

See the examples directory for more example scripts.

task fibonacci gets input
  when input <= 1
    return input
  end

  // return fib(n-1) + fib(n-2);
  value n_minus_1 is input - 1
  value n_minus_2 is input - 2
  value result_1 is from fibonacci with n_minus_1
  value result_2 is from fibonacci with n_minus_2
  return result_1 + result_2
end

value result is from fibonacci with 9
log 'result: {result}'

result: 34

using fetch

task main
  value body is from fetch with 'http://time.evrythng.com/time'

  // Convert string to object
  object json is body

  log 'The time is {json.timestamp}'
end

run main

• Utilities (date/time, random numbers, read/write files, etc.)
• Evaluate function calls inline (multiple passes)
• Multiline test (e.g: to test object from variable)