plv8 SQL for the |> and <| operators (aka LiveScript application): SELECT '{"hello": [1,2,3]}' |> 'this.hello[0]'; SELECT 'this.hello[0]' <| '{"hello": [1,2,3]}';

apply.sql

CREATE OR REPLACE FUNCTION plv8x.json_eval(code text) RETURNS plv8x.json AS $$
    return JSON.stringify(
        eval("(function(){return #code})").apply(this)
    );
$$ LANGUAGE plls IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION plv8x.json_eval(data plv8x.json, code text) RETURNS plv8x.json AS $$
    return JSON.stringify(
        eval("(function(){return #code})").apply(JSON.parse(data))
    );
$$ LANGUAGE plls IMMUTABLE STRICT;
CREATE OR REPLACE FUNCTION plv8x.json_eval(code text, data plv8x.json) RETURNS plv8x.json AS $$
    return JSON.stringify(
        eval("(function(){return #code})").apply(JSON.parse(data))
    );
$$ LANGUAGE plls IMMUTABLE STRICT;
 

DROP OPERATOR IF EXISTS |> (text);
CREATE OPERATOR |> (
    RIGHTARG = text,
    PROCEDURE = plv8x.json_eval
);
DROP OPERATOR IF EXISTS |> (plv8x.json, text);
CREATE OPERATOR |> (
    LEFTARG = plv8x.json,
    RIGHTARG = text,
    COMMUTATOR = <|,
    PROCEDURE = plv8x.json_eval
);
DROP OPERATOR IF EXISTS <| (text, plv8x.json);
CREATE OPERATOR <| (
    LEFTARG = text,
    RIGHTARG = plv8x.json,
    COMMUTATOR = |>,
    PROCEDURE = plv8x.json_eval
);
 
SELECT '{"hello": [1,2,3]}' |> 'this.hello[0]';
SELECT 'this.hello[0]' <| '{"hello": [1,2,3]}';
SELECT |> '1+1';