Cast

The tiders-cast crate provides blockchain-aware type casting for Arrow columns. It extends standard Arrow casting with support for types common in blockchain data.

Python Usage

Cast by Column Name

import pyarrow as pa
from tiders_core import cast

# Cast specific columns to target types
casted_batch = cast(
    [("block_number", pa.int64()), ("value", pa.decimal128(38, 0))],
    record_batch,
)

Cast by Type

Convert all columns of one Arrow type to another:

from tiders_core import cast_by_type

# Convert all decimal256 columns to decimal128
casted_batch = cast_by_type(
    pa.decimal256(76, 0),
    pa.decimal128(38, 0),
    record_batch,
    allow_cast_fail=True,
)

This is useful when a downstream system (like DuckDB) doesn’t support certain types.

Encoding Utilities

The cast module also provides encoding/decoding functions:

from tiders_core import hex_encode, prefix_hex_encode, base58_encode

# Encode binary columns
hex_batch = hex_encode(record_batch)           # "0a1b2c..."
prefixed = prefix_hex_encode(record_batch)     # "0x0a1b2c..."
b58_batch = base58_encode(record_batch)        # Base58 format

Rust API

See the tiders_cast rustdoc for the full API.