Introduction

Arr.ai is many things, but it is first and foremost a data representation and transformation language. This section provides a complete reference of its syntax and features.

If you're new to arr.ai, you may want to start with Getting Started and Tutorial sections.

About the name

The domain name arr.ai was available and there was some irony in the fact that a language called arr.ai doesn't have arrays (though it kind of does; see below).

Some lexical conventions

Arr.ai has a rich syntax, which we won't dive into just yet. A few elements are worth covering upfront to aid comprehension below.

1. Identifiers: Parameter and variables names start with _, @, $ or a Unicode letter, and may continue with a sequence of any of these and Unicode decimal numbers.

   Examples: x, $y, Username, i0, @j12, apple_π

   The identifier . is a special case. It is often used as a default argument in transform expressions.

2. Keywords: The following names are predefined and cannot be reassigned as parameter or variable names: true, false, let

3. Comments: Comments start with a # and end at the end of the line.

   Example: # Comment on comments.

4. Offset collections: In the string "hello", the first character, h, is at position zero. In the alternate form 12\"hello", the h is at position 12 and the remaining characters occupy positions 13–16. This is known as an offset-string. Likewise, 5\[1, 2, 3] represents an offset array.