ExpressionFunctionType

The kinds of expression function.

Note: boolean predicates are scalar functions with returnType: 'boolean'; the boolean aggregation operators (WHERE, threshold comparators) are part of aggregated. observable are the brace-only history readers (CHANGE_COUNT{}, PREVIOUS{}, ROW_AGE{}, …) and their clause keywords (ANY_COL, WITHIN, LAST_N, ALL_ROWS, TRIGGER).

export type ExpressionFunctionType = 'scalar' | 'aggregated' | 'observable';