Feedback on qualified names #152

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1. mchav commented on Feb 19, 2026

   

   mchav

   on Feb 19, 2026

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   Why qualified imports

   I guess I never knew they were a problem cause all the tools I use assume they are e.g. import pandas as pd and import polars as pl, import qualified Data.Text as T and so forth for Haskell maps, sets and other things that are expected to clash a lot with Prelude. But now that you point it out I see why they are annoying. I'm curious how you use packages like containers/text without all the namespace clashes?

   Why the functions namespace

   The expression stuff came a little later and at the time I was writing a lot of pyspark at work. PySpark puts all the columns looking functions in a functions namespace. Aside from that a lot of the initial functions clashed with other functions in the uber namespace.

   E.g.

   D.mean col df -- get mean of a column as a value.
   D.derive "m" (F.mean col) df -- mean expression

   Monad/applicative/integral instances

   toInteger is undefined for expressions unless you have an accompanying dataframe. So are toRational and toEnum which integral requires. I guess we could make those specific functions throw exceptions but fully define all the other functions in the class so they don't use them but then you get surprising behaviour from time to time when you assume toInteger works.

   Monad instances require the type to be unconstrained. We at least need a show constraint so probably not possible. Also some laws would just not hold for expressions. It gets messy. But this is something I've fought with GHC about for months. Open to solutions.
2. maxigit commented on Feb 19, 2026

   

   maxigit

   on Feb 19, 2026

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   I'm curious how you use packages like containers/text without all the namespace clashes?

   I rarely need everything from everything in one file, so I usually manage to import the main one unqualified and hide/expose/qualify the extra one. But I'll reuse the same name for the same package if possible as in

   import Text.Megaparsec qualified as P
   import Text.Megaparsec.Char qualified as P
   import Text.Megaparsec.Char.Lexer qualified as P hiding (space)
   

   I don't like Haskell qualified syntax because it makes things look like constructor or type. Python panda.read_csv is consistent with OO python syntax. F.col looks like F_col.

   Aside from that a lot of the initial functions clashed with other functions in the uber namespace.

   Well, it is an egg and chicken situation. If you qualify, you can have duplicate and once you have duplicates you'll need to qualify :-)

   toInteger is undefined for expressions unless you have an accompanying dataframe

   Fair enough, I didn't think of toInteger. I'm not sure why it is even need to integer division. It is probably due to the original Num hierarchy. It is just odd that you can use / and * from the Prelude, but not mod and div ...