First dataframe

from_pairs creates a frame in the order you list its columns. Each column must have the same number of rows. This example has two rows, so main returns 2:

module Coral.Doc01
import Coral.Frame (FloatCol, StringCol, from_pairs, nrows)
export (main)
def main() -> i64 = {
  prices = FloatCol(to_tensor([1.0f32, 2.0f32]))
  names = StringCol(["a", "b"])
  frame = from_pairs([("price", prices), ("name", names)])
  nrows(frame)
}

In your Reef project, replace Coral in module Coral.Doc01 with the project's module_prefix and save the program as src/doc01.ch. Keep import Coral.Frame unchanged. Run chelis reef build, then chelis eval --file src/doc01.ch to see the result.

FloatCol stores a tensor[n, f32]; StringCol stores a List[string]. Use int_col_of_list for ordinary i64 columns so Coral creates the corresponding all-false missing-value mask. Construction covers the other column forms.