Lists

Lists are mutable ordered collections.

Create a list

Make a list called scores.

A new list starts empty.

Add values

Add 10 to scores.
Add 20 to scores.
Add 30 to scores.

Get an item

ENG uses ordinal names:

Let first_score be Get the first item of scores.
Let second_score be Get the second item of scores.

Numeric ordinals are also supported:

Let value be Get the 1st item of scores.

The user-facing ordinals are one-based: 1st means the first item. Internally, the VM converts the ordinal to a zero-based vector index.

Set an item

Set the first item of scores to 5.
Set the 2nd item of scores to 25.

The item must already exist; setting an out-of-range item is a runtime error.

Length

Print the length of scores.

The result is a number.

Supported ordinal words

The lexer defines:

• first
• second
• third
• fourth
• fifth

Numeric ordinal suffixes such as 1st, 2nd, 3rd, and 4th are also recognized.

Out-of-range access

Trying to read or set an item outside the list produces a runtime error explaining the requested user-facing index and the current list size.