Idea: OverloadedStrings and OverloadedLists for PortName?

[dramforever]

Synthesize annotations are a bit annoying to read. The signal-to-noise ratio is pretty bad because most port names (like q or cin) are much shorter than PortName and PortProduct.

For example, this is from #654:

{-# ANN f
   (Synthesize
      { t_name   = "f"
      , t_inputs = [ PortName "a"
                   , PortProduct "" [ PortName "b", PortName "c" ] ]
      , t_output = PortProduct "res" [PortName "q"] }) #-}

But with -XOverloadedStrings and -XOverloadedLists and some instances, PortName and PortProduct "" can be elided like this:

{-# ANN f
   (Synthesize
      { t_name   = "f"
      , t_inputs = [ "a", [ "b", "c" ] ]
      , t_output = PortProduct "res" [ "q" ] }) #-}

The instances look like this:

import GHC.Exts

instance IsString PortName where
    fromString = PortName

instance IsList PortName where
    type Item PortName = PortName

    fromList = PortProduct ""

    toList = error "toList for PortName is not implemented"

---

Pros:

• Shorter annotation is both easier to read and easier to write
• Easy implementation
• Backwards compatible AFAIK, and can mix with other PortNames (see PortProduct "res" [ ... ] above)

Cons:

• Can be confusing for someone not familiar with what's going on
• Two ways to write the same thing. Which one for documentation and tutorial?
• toList always errors. Maybe we can only have IsString and only avoid typing out PortName for every port?