Eval syntax.md

Eval syntax

You can write code in a functional style by using the eval syntax. Be careful not to go crazy with this one and go all nested and lispy! In order to keep your scripts legible, it's better to avoid nested logic.

Basic usage

Inside a data block, you can use any command prefixed with : to have it evaluated inline.

For example:

Code example: Simple Eval

Add:
  - :Add:
      - 1
      - 2
  - 3

Expected output: 6

This is equivalent to:

Code example: No Eval

Add:
  - 1
  - 2
---
Add:
  - ${output}
  - 3

Expected output: 6

Example with For each

Here's another example of how you could use this. Let's say we want to sum the ages of the main characters. Remember that For each returns a list of outputs for each item. We can then use that list in Add.

Code example: Eval with for each

${cast}:
  - first name: Romeo
    last name: Montague
    age: 16
  - first name: Juliet
    last name: Capulet
    age: 13

Add:
  :For each:
    ${character} in: ${cast}
    Output: ${character.age}

Expected output: 29

Note that you can 'unfold' this example to make it more linear and less nested:

Code example: Alternative to nesting

For each:
  ${character} in: ${cast}
  Output: ${character.age}
Add: ${output}

Expected output: 29

In the end it's a matter of taste. Instacli scripts are meant to be simple and legible. Choose the style that best expresses how you would explain what is going on in words.