Library Alignment

This page documents operators that are currently available in only one of the Bmg implementations, along with suggestions for potential cross-implementation alignment.

Currently in Ruby Only

The following operators are available in Bmg (Ruby) but not yet in Bmg.js (TypeScript):

page

Pagination with ordering

rel.page([[:name, :asc]], 1, page_size: 10)

Retrieves a specific page of results with consistent ordering. Useful for building paginated APIs.

rxmatch

Regex match restriction

rel.rxmatch(:name, /^S/)

Filter tuples where an attribute matches a regular expression pattern.

autosummarize

Automatic summarization

rel.autosummarize([:group_key], :sum)

Automatically summarizes all non-key numeric attributes using the specified aggregator.

undress

Convert to scalars

rel.undress

Converts single-attribute tuples to scalar values.

images

Multiple image shortcut

rel.images(other1, other2, ...)

Shortcut for applying multiple image operations in sequence.

generator

Sequence generation

Bmg.generate(1, 100)

Creates a relation from a sequence of values, similar to PostgreSQL’s generate_series.

Currently in TypeScript Only

The following operators are available in Bmg.js (TypeScript) but not yet in Bmg (Ruby):

intersect

Set intersection

left.intersect(right)

Returns tuples that exist in both relations.

wrap

Wrap attributes

rel.wrap(['a', 'b'], 'nested')

Combines multiple attributes into a single tuple-valued attribute.

one

Extract single tuple

rel.one()

Extracts a single tuple, throwing if not exactly one exists.

isEqual

Set equality check

rel1.isEqual(rel2)

Checks if two relations contain the same tuples.

Alignment Opportunities

High Priority

These would provide the most value if implemented in both libraries:

Operator	Missing from	Rationale
`intersect`	Ruby	Common set operation, completes the set algebra
`wrap`	Ruby	Inverse of `unwrap`, needed for structural completeness
`page`	TypeScript	Essential for building paginated APIs

Medium Priority

Operator	Missing from	Rationale
`one`	Ruby	Useful for extracting single results safely
`isEqual`	Ruby	Valuable for testing and assertions
`rxmatch`	TypeScript	Useful for pattern-based filtering

Notes

to_a (Ruby) and toArray() (TypeScript) serve the same purpose
y_by_x (Ruby) and yByX (TypeScript) serve the same purpose
Some operators like autosummarize and undress are Ruby-specific conveniences that may not fit TypeScript’s design philosophy

Contributing

Contributions to align the libraries are welcome! See the respective repositories: