I am working on big update to my ecto_function library. It is inspired by Nx support for defn functions, and my thought was “well, why not, check if it will be possible to do something similar for DB queries”. It seems that it is more or less possible:

defq clamp(val) do
  cond do
    val < 0 -> 0
    val > 1 -> 1
    true -> val
  end
end

Which when used like:

from e in "entires",
  select: clamp(e.value)

Will be translated to:

SELECT
  CASE
  WHEN e.value < 0 THEN 0
  WHEN e.value > 1 THEN 1
  ELSE e.value
  END
FROM entries e

This may be useful when one would like to move more computation to the DB where sometimes it may make more sense (move your computation to your data instead of moving data to your computation).

Question is whether there will be will for such constructs and whether community will find something like that useful.

There is already working PoC on the GitHub

https://github.com/hauleth/ecto_function/pull/4

But I would live to get some more insights before I dig more into it.