Postgresql logical implication operator

logical_implication.sql

CREATE FUNCTION
  logical_implication(a boolean, b boolean)
RETURNS
  boolean
LANGUAGE
  sql
IMMUTABLE
PARALLEL SAFE
RETURNS NULL ON NULL INPUT
COST 1
AS $$
  SELECT NOT a OR b
$$
;

CREATE OPERATOR ->
  ( function = logical_implication
  , leftarg  = boolean
  , rightarg = boolean
  )
;

Note that when you wish to use this operator in a join condition, or indexes you should define additional properties of the operator to allow these operations to be executed efficiently: https://www.postgresql.org/docs/12/xoper-optimization.html

you can simply 'OR NOT'

Not checked the boolean table for that one yet, still I think that OR NOT is "hard" on the human mind in regular SQL, especially as the human than had to triple check precedence rules. I'd still prefer the operator.