Haskell example of spreadsheet-like column sorting

table_sort.hs

import Data.List
import Data.Ord

data Field = Str String
           | Num Double
           deriving (Show, Eq, Ord)

data Column = Column { fields::[Field] }
            deriving (Show, Eq, Ord)

data Table = Table { columns::[Column] }
            deriving (Show, Eq, Ord)

sortTableByColumn :: Table -> Int -> Table
sortTableByColumn t i = tableFromRows $ sortRows
    where sortRows = sortBy (comparing (!! clip i)) $ rows
          clip = max 0 . min ((length . columns $ t) - 1) -- prevent out of bounds index
          rows = transpose . fmap fields . columns $ t
          tableFromRows = Table . fmap Column . transpose


column1 = Column [Num 8, Str "pear", Str "apple", Str "shoes", Num 10]
column2 = Column [Num 8, Num 12, Str "apple", Str "pair", Num 10]
column3 = Column [Num 15, Num 1, Str "zebra", Str "bear", Num 12]

table = Table [column1, column2, column3]

{- examples:
sortTableByColumn table 0
sortTableByColumn table 2
-}

Inspired by sketchyTech’s Swift blog post which tackles the same problem using Swift.