Changing columns

with_column(frame, name, column) adds a column or replaces one with the same name. mutate does the same thing. The new column must have the frame's row count. rename changes a column name and rejects a name already in use; drop_column removes a named column.

module Coral.BookMutation
import Coral.Frame (FloatCol, from_pairs, with_column, rename, drop_column, int_col_of_list, ncols)
export (main)
def main() -> i64 = {
  frame = from_pairs([("price", FloatCol(to_tensor([10.0f32, 20.0f32])))])
  renamed = rename(frame, "price", "cost")
  extended = with_column(renamed, "qty", int_col_of_list([2i64, 3i64]))
  trimmed = drop_column(extended, "cost")
  ncols(trimmed)
}

main returns 1: only qty remains. The operations return new frame values; use the returned frame for subsequent steps.