@spec arrow_dtype_to_explorer(arrow_dtype()) :: {:ok, atom()} | {:error, String.t()}

Convert an Arrow dtype string to an Explorer dtype atom.

Returns {:ok, explorer_dtype} or {:error, message}.

Integer dtypes (s8–s64, u8–u64) all map to :integer because Explorer does not distinguish integer widths in its dtype system. Float dtypes (f32, f64) map to :float.

@spec arrow_dtype_to_nx(arrow_dtype()) :: {:ok, nx_dtype()} | {:error, String.t()}

Convert an Arrow dtype string to an Nx dtype tuple.

Returns {:ok, nx_dtype} or {:error, message}.

Boolean columns ("bool") map to {:u, 8} because Nx represents booleans as unsigned 8-bit integers with values 0 and 1.

@spec arrow_dtype_to_type_atom(arrow_dtype()) :: {:ok, atom()} | {:error, String.t()}

Convert an Arrow dtype string to an Arrow type atom.

Returns {:ok, type_atom} or {:error, message}.

Examples

iex> ExArrow.Schema.Mapper.arrow_dtype_to_type_atom("s64")
{:ok, :int64}

iex> ExArrow.Schema.Mapper.arrow_dtype_to_type_atom("bool")
{:ok, :boolean}

@spec arrow_type_atom_to_dtype(atom()) :: {:ok, arrow_dtype()} | {:error, String.t()}

Convert an Arrow type atom (as returned by ExArrow.Schema.fields/1) to an Arrow dtype string.

Returns {:ok, dtype_string} or {:error, message}.

This bridges the NIF schema representation (atoms like :int64) to the dtype strings used by column buffer NIFs ("s64").

Examples

iex> ExArrow.Schema.Mapper.arrow_type_atom_to_dtype(:int64)
{:ok, "s64"}

iex> ExArrow.Schema.Mapper.arrow_type_atom_to_dtype(:boolean)
{:ok, "bool"}

iex> ExArrow.Schema.Mapper.arrow_type_atom_to_dtype(:timestamp)
{:error, "unsupported Arrow type atom for dtype mapping: timestamp"}

@spec explorer_dtype_to_arrow(atom()) :: {:ok, arrow_dtype()} | {:error, String.t()}

Convert an Explorer dtype atom to an Arrow dtype string.

Returns {:ok, dtype_string} or {:error, message}.

Supported Explorer dtypes

Explorer dtypes :date, :datetime, :duration, and :nil are not yet mapped and return an error. These will be added as the NIF layer gains support for the corresponding Arrow types.

@spec numeric?(arrow_dtype()) :: boolean()

Returns true if the given Arrow dtype string maps to a numeric Nx dtype, false otherwise.

Examples

iex> ExArrow.Schema.Mapper.numeric?("s64")
true

iex> ExArrow.Schema.Mapper.numeric?("bool")
true

iex> ExArrow.Schema.Mapper.numeric?("utf8")
false

@spec nx_dtype_to_arrow(nx_dtype()) :: {:ok, arrow_dtype()} | {:error, String.t()}

Convert an Nx dtype tuple to an Arrow dtype string.

Returns {:ok, dtype_string} or {:error, message}.

Supported Nx dtypes

Nx does not have a dedicated boolean dtype; booleans are represented as {:u, 8} with values 0 and 1. Arrow Boolean columns map to {:u, 8} via arrow_dtype_to_nx/1.