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module Y2016.M12.D20.Exercise where
-- below import available from 1HaskellADay git repository
import Data.SymbolTable
import Data.SymbolTable.Compiler
import Data.SAIPE.USStates
So, yesterday, as you see from the import above, we enumerated the US States!
YAY! *throws confetti
NOW! Using the same data-set, stored at:
let's enumerate the US Counties.
A slight problem: the SymbolTable-type works with strings, SO you can enumerate
the strings, sure.
(I think any Ord-type should work, but hey.)
('but hey' is a perfect counter-argument to anything. Try it sometime.)
Well you can do that. No problem. But how do you associate an atomic County
symbol with its State?
Today's Haskell problem.
1) create a complied symbol table of Data.SAIPE.USCounties, enumerated and
usCountySymbols :: FilePath -> FilePath -> IO ()
usCountySymbols gzipSAIPEdata modul = undefined
data USCounty = PlaceholderForCompiledUSCountyType
-- see yesterday's exercise for guidance
Now, USState and USCounty and their associations are all deterministic (as we'd
say in Prolog-parlance), so how do we do a lookup for the USState of a USCounty
in a deterministic fashion?
usStateFor :: USCounty -> USState
usStateFor county = undefined
-- 2) define usStateFor as above that guarantees to return a USState value
-- (the correct one, at that) for the input USCounty value.
-- hint: A USCounty's USState is a fact. No doubt.