Update tutorials to use expression syntax.

Missed some parts.

Author: mchav

docs/coming_from_polars.md

@@ -290,7 +290,7 @@ We implicitly create a `Count` variable as the result of grouping by an aggregat
 ```haskell
 let decade = (*10) . flip div 10 . year
 df_csv
-    |> D.derive "decade" decade "birthdate"
+    |> D.derive "decade" (lift decade (col @date "birthdate"))
     |> D.select ["decade"]
     |> D.groupByAgg D.Count ["decade"]
 ```

docs/exploratory_data_analysis_primer.md

@@ -101,7 +101,7 @@ In the housing dataset it'll tell how "typical" our typical home price is.
 ghci> import Data.Maybe
 ghci> m = fromMaybe 0 $ D.mean "median_house_value" df
 206855.81690891474
-ghci> df |> D.derive "deviation" (\v -> abs (v - m)) "median_house_value" |> D.select ["median_house_value", "deviation"] |> D.take 10
+ghci> df |> D.derive "deviation" (D.col "median_house_value" - D.lit m) |> D.select ["median_house_value", "deviation"] |> D.take 10
 -----------------------------------------------
 index | median_house_value |     deviation     
 ------|--------------------|-------------------
@@ -119,12 +119,12 @@ index | median_house_value |     deviation
 9     | 261100.0           | 54244.18309108526
 ```
 
-Read left to right, we begin by calling `derive` which applies a function to a given column and stores the result in a target column. The order of arguments is `derive <target column> <function> <deriving column> <dataframe>`. We then select only the two columns we want and take the first 10 rows.
+Read left to right, we begin by calling `derive` which creates a new column computed from a given expression. The order of arguments is `derive <target column> <expression>  <dataframe>`. We then select only the two columns we want and take the first 10 rows.
 
 This gives us a list of the deviations. From the small sample it does seem like there are some wild deviations. The first one is greater than the mean! How typical is this? Well to answer that we take the average of all these values.
 
 ```haskell
-ghci> withDeviation = df |> D.derive "deviation" (\v -> abs (v - m)) "median_house_value" |> D.select ["median_house_value", "deviation"]
+ghci> withDeviation = df |> D.derive "deviation" (D.col "median_house_value" - D.lit m) |> "median_house_value" |> D.select ["median_house_value", "deviation"]
 ghci> D.mean "deviation" withDeviation
 Just 91170.43994367732
 ```