[WIP] Add DSL for datetime/duration

[mdedetrich]

Problem

This PR is intended to add a DSL for the various DateTime/Duration functions in Postgres. The intention is to allow you do things like

query[Table].filter(t => t.time < now() - 5.minutes)

where now() translates to the postgres now() function and the 5.minutes translates to postgres Interval type.

Solution

TBD

Notes

Since Encoder/Decoder for LocalDate is already defined in the base Encoders.scala and Decoders.scala JDBC files, we override it our custom Postgres datetime Encoder/Decoder. While there is an argument that this is pointless and we should just not include the these Encoder's/Decoder's which are already defined, the Postgres JDBC converters are both faster and is what is official supported for use when using Postgres JDBC.

Also since we are adding capability for the datetime types provided by JSR-310 this effectively means that quill will only support JVM versions 1.8+ effective of this PR. I don't know how much of an issue this is, however note that JVM 1.6 is already out of EOL support from Oracle. The only area I could practically see this being a problem is if someone is using Quill on Android (is anyone doing this?)

Checklist

• Unit test all changes
• Update README.md if applicable
• Add [WIP] to the pull request title if it's work in progress
• Squash commits that aren't meaningful changes
• Run sbt scalariformFormat test:scalariformFormat to make sure that the source files are formatted

@getquill/maintainers

[deusaquilus]

@mdedetrich This is really great, I’m hoping we can incorporate stuff like this into other dialects! There are probably some things that need to be added to the Postgres Dialect tokenizer as well as the parser for this to work.

Come to think of it, the easiest way to implement this is going to be with Quats that represent time intervals. Otherwise we’d need to add a bunch of AST elements to represent the different operations.

I’m going to document how to approach this issue using Quats in the coming days.

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