Language basics

Path navigation

Use dot notation to walk into the input. Each dot descends one level.

media.transcript                    the transcript for this window
media.contextual.garm.risk          the brand-safety risk of this scene
usage.output_tokens                 a field of a model response

A path that doesn't exist evaluates to nothing, without raising an error. This applies at any depth, so a missing intermediate object doesn't break the expression.

media.contextual.nonExistent                 nothing
media.contextual.nonExistent.deeply.nested   nothing

Use [n] to index an array, starting at zero, and [-1] to take the last element.

media.frames[0]              the first sampled frame
media.clip.events[0].keyword the keyword of the first clip in the window

Mapping over an array

Applying a path or an object constructor to an array maps it over every element. Inside the map, $ is the current element.

media.clip.events.keyword
  ["touchdown", "interception"]

media.clip.events.{ "label": keyword, "at": startPts }
  [{ "label": "touchdown", "at": 900000 }, ...]

media.frames.{ "type": "image", "source": { "type": "base64", "media_type": "image/jpeg", "data": $ } }
  one object per frame

String concatenation

The & operator joins two values into a string. Non-string values are converted automatically.

"Summary: " & media.contextual.summary
"risk=" & media.contextual.garm.risk & " categories=" & $count(media.contextual.categories)

Conditional expressions

Use the ternary operator to choose between two values.

condition ? value_if_true : value_if_false

You can nest ternary expressions for multi-way branching.

$exists(media.contextual.summary) ? media.contextual.summary : "No summary available."

media.contextual.garm.risk = "FLOOR" ? "block"
  : media.contextual.garm.risk = "HIGH" ? "review"
  : "allow"

Variable binding

Inside parentheses, use := to name an intermediate value, and semicolons to separate statements. The last statement is the value of the expression. Bound variables exist only within their parentheses.

(
  $risk := media.contextual.garm.risk;
  $flagged := $join(media.contextual.garm.flagged, ", ");
  {
    "text": "Risk " & $risk & " (" & $flagged & "). Write a one-line advertiser note."
  }
)