Evaluate a duckplyr pipeline with dynamic Rducks scalar UDFs

Registers selected R functions as dynamic-argument Rducks scalar UDFs on a DuckDB connection, rewrites matching calls in a captured duckplyr expression to duckplyr's DuckDB-function escape hatch, and evaluates the rewritten expression. This lets a duckplyr pipeline stay in DuckDB for those calls instead of falling back to dplyr, provided every registered function has an explicit return type.

Usage

rducks_with_duckplyr(
  con,
  expr,
  returns,
  env = parent.frame(),
  null_handling = c("default", "special"),
  exception_handling = c("rethrow", "return_null"),
  side_effects = FALSE,
  mode = "scalar"
)

# S3 method for class 'duckdb_connection'
with(
  data,
  expr,
  ...,
  rducks_returns,
  rducks_env = parent.frame(),
  rducks_mode = "scalar"
)

Arguments

con: A duckdb_connection with Rducks enabled.
expr: A duckplyr expression or pipeline to evaluate.
returns: Named list or named character vector of return types. Names must be R function names visible from env; values are Rducks type descriptors or scalar type tokens, e.g. list(score_fun = DOUBLE).
env: Evaluation environment for expr and function lookup.
null_handling, exception_handling, side_effects: Passed to rducks_register_scalar_udf().
mode: Rducks scalar-UDF evaluation mode for registered helpers. "scalar" calls the R helper once per row; "vectorized" calls it once per DuckDB chunk and requires a vectorized helper.
data: A duckdb_connection with Rducks enabled.
...: Reserved for future extensions; must be empty.
rducks_returns: Named return-type list for dynamic Rducks UDFs.
rducks_env: Evaluation environment for expr and function lookup.
rducks_mode: Rducks scalar-UDF evaluation mode for helpers registered through with.duckdb_connection().

Value

The value of the evaluated expression.

Details

This helper intentionally requires return-type declarations: DuckDB needs a scalar function's return type during planning even when its input arguments are accepted dynamically. Dynamic arguments are a duckplyr-oriented convenience path that uses nanoarrow's default input conversion. The duckplyr bridge defaults to mode = "scalar" because ordinary R calls in duckplyr SQL expressions are written as row-wise scalar functions. Set mode = "vectorized" only for helpers that accept full vectors/chunks and return a vector of the same length. The selected Rducks execution plan is still taken from con, so arrow_c and arrow_ipc plans can be selected with rducks_set_execution_plan() before evaluating the duckplyr expression. Use explicit args in rducks_register_scalar_udf() when you need Rducks' declared composite, exotic, or special-NULL input semantics.