Advanced Variable Expansion

[benbjohnson]

Per suggestion from @kentcdodds, this issue exists to describe additional operators in variable expansion.

The initial suggestion is for a "includes" operator. Environment variables don't necessarily have a format (e.g. CSV) so it might make more sense to have a CONTAINS operator instead.

Usage

Possible formats for usage:

${"den,maa" CONTAINS FLY_REGION}

${CONTAINS("den,maa", FLY_REGION)}

Alternatives

Another option could be to implement a regex operator to make it more flexible:

${"den,maa" ~= FLY_REGION}

Maybe that's more confusing though. ¯\_(ツ)_/¯