scanCsv

LazyFrame scanCsv(string path,  Schema schema,
       CsvReadPolicy policy =  CsvReadPolicy.init,
       CsvScanMode mode =  CsvScanMode.AUTO)

@trusted

Opens a CSV file as a lazy scan source: the returned deferred frame pulls one batch per policy.chunkRows rows when collected or streamed, without loading the file first. The schema is explicit (inference arrives with its own contract); parse errors surface in file order at the first failing batch, exactly like the eager serial reader.

Parameters

`path`	the CSV file path
`schema`	the expected columns (by name when `policy.hasHeader`, by position otherwise)
`policy`	the reading policy
`mode`	the input mode (AUTO: mmap for regular files, buffered otherwise)

Returns

the deferred frame over the scan source.

Throws

DataFrameException when the file cannot be opened, or

MMAP is requested for a source that cannot be mapped.

LazyFrame scanCsv(File input,  Schema schema,
       CsvReadPolicy policy =  CsvReadPolicy.init)

@trusted

Ditto, from an already-open handle (a pipe, stdin, a socket stream - the buffered mode by construction; the source owns the handle until close()).