[Haskell-cafe] A type level puzzle

[Silvio Frischknecht]

I'm not going to do the whole thing for you but I can help start you off.

The type level string you think of is called Symbol. Symbol is a kind on
it's own and not (*) it has a type for every string. You can use the
functions in the following link to work with them.

https://hackage.haskell.org/package/base-4.8.1.0/docs/GHC-TypeLits.html

so you might have

newtype (symbol :: Symbol) ::: value = Field value

you can basically use any typelevel combinator you want for Sum e.g.

("foo" ::: Int) `(,)` ("bar" ::: Char) `(,)` ...

or make your own

You will have to use type families which are basically type level
functions to merge two sums.

If you run into trouble you can have a look at the following link which
does some similar things.

https://hackage.haskell.org/package/type-level-sets-0.5/docs/Data-Type-Set.html


P.S. Prepare for a headache

Cheers

Silvio