6.4. Lambda Expressions

Lambda expressions are written with ->:

  1. x -> x + 1
  2. (x, y) -> x + y
  3. x -> regexp_like(x, 'a+')
  4. x -> x[1] / x[2]
  5. x -> IF(x > 0, x, -x)
  6. x -> COALESCE(x, 0)
  7. x -> CAST(x AS JSON)
  8. x -> x + TRY(1 / 0)

Most SQL expressions can be used in a lambda body, with a few exceptions:

  • Subqueries are not supported. x -> 2 + (SELECT 3)
  • Aggregations are not supported. x -> max(y)

原文: https://prestodb.io/docs/current/functions/lambda.html