Design Decisions

rsspell is built with speed and simplicity in mind. This section covers key design choices made during development.

Built-in en-US Dictionary

The rsspell tool includes the en-US dictionary (dictionaries/en_US.aff and dictionaries/en_US.dic) embedded directly in the binary. This choice was made for several reasons:

1. Immediate Value: The tool works out-of-the-box for the most common use case (English spell-checking) without requiring any initial setup or dictionary downloads.
2. Offline Functionality: Users can perform spell-checks in English even without an active internet connection.
3. Robust Fallback: The embedded dictionary serves as a reliable default if external dictionary management fails or is not used.

Dictionary Structure (Hunspell Format)

The dictionary is split into two files (dictionaries/en_US.aff and dictionaries/en_US.dic) following the Hunspell standard. This dual-file approach is used for affix compression, which significantly reduces the dictionary’s footprint:

• .dic (Dictionary File): Contains a list of base words (stems) along with flags that indicate which rules apply to them.
• .aff (Affix File): Defines the grammatical rules for prefixes and suffixes (e.g., how to handle plurals, tenses, and possessives).

By separating the rules from the word list, rsspell can recognize hundreds of thousands of word variations without needing to store them all explicitly, keeping the binary size small and memory usage efficient.

Supported Formats

rsspell currently focuses on file formats where textual content is mixed with structured data.

Markdown

rsspell uses the pulldown-cmark library to parse Markdown documents. This ensures that only the text content is checked, while Markdown syntax like links, code blocks, and headers are properly ignored or parsed.

SVG

For SVG files, rsspell parses the XML structure and checks text elements. This is useful for diagrams and icons where typos can often go unnoticed.