Config.XOfTheDay
Configuration constants for the "X of the Day" feature: paths, thresholds, and domain exclusions
Read this when Use this page when tracing the Haskell build pipeline, generators, metadata code, or backend utility behavior around Config.XOfTheDay.
Overview
This module centralizes all configuration for gwern.net's "X of the Day" features—Quote of the Day, Site of the Day, and Annotation of the Day. Each feature displays a rotating selection of curated content on the homepage, drawn from metadata databases.
The module defines three categories of configuration: (1) file paths to the source databases and output HTML files, (2) quality thresholds that filter which entries qualify for rotation, and (3) a comprehensive domain blacklist preventing certain sites from appearing in the Site of the Day feature.
The blacklist is notably large (~2,300 domains) and excludes common platforms (GitHub, Wikipedia, Twitter/X), major publications (NYT, Guardian, Nature), academic repositories (arXiv, JSTOR), and gwern.net itself—the rationale being these are either too common to be interesting discoveries or would create self-referential recommendations.
Public API
quoteDBPath :: FilePath
Path to the quote database: metadata/quotes.hs
quotePath :: FilePath
Output path for today's quote: metadata/today-quote.html
siteDBPath :: FilePath
Path to the site database: metadata/sites.hs
sitePath :: FilePath
Output path for today's site: metadata/today-site.html
annotDayDB :: String
Path to the annotation database: metadata/annotations.hs
annotPath :: String
Output path for today's annotation: metadata/today-annotation.html
minAnnotationAbstractLength :: Int
Minimum character length for annotation abstracts to qualify: 2000
Comment notes this threshold yielded 3,313 qualifying entries (vs 10,046 at >500 chars).
siteLinkMin :: Int
Minimum number of links required for a site to qualify: 3
siteBlackList :: [T.Text]
List of domain names excluded from Site of the Day recommendations.
Internal Architecture
The module contains no logic—it's purely declarative constants. The blacklist is a simple list literal of T.Text domain strings, designed for O(n) membership checks (or conversion to a Set by consumers).
Database File Format
The .hs extension on database files suggests they use Haskell's Read/Show serialization rather than JSON or YAML. This allows type-safe deserialization directly into Haskell data structures.
Output Files
The today-*.html files are pre-rendered HTML fragments included in page templates, regenerated during each build cycle.
Key Patterns
Threshold Tuning Comments: The module includes inline documentation about threshold selection rationale:
-- at >500, yielded 10,046 on 2023-03-08; >2,000 yielded a more reasonable 3,313
This captures the empirical reasoning for configuration choices, useful for future adjustments.
Domain Blacklist Organization: The bulk of the list is roughly alphabetical in chunks of ~5 domains per line (with later additions appended unsorted at the end), keeping diffs readable and merges less conflicting.
Configuration
All values are compile-time constants. To modify:
| Setting | Current Value | Effect |
|---|---|---|
minAnnotationAbstractLength | 2000 | Raises bar: fewer but meatier annotations |
siteLinkMin | 3 | Ensures sites have meaningful presence in annotations |
siteBlackList | ~2,300 domains | Prevents generic/common sites from appearing |
Integration Points
Consumers: The build system modules that generate X of the Day content import these constants:
- Selection logic uses thresholds to filter candidates
- HTML generators write to the configured output paths
- Recommendation engine checks blacklist before selecting sites
Related metadata files:
metadata/quotes.hs- Quote databasemetadata/sites.hs- Site recommendation databasemetadata/annotations.hs- Full annotation database
See Also
- XOfTheDay.hs - Main module consuming this configuration
- Hakyll.hs - Site generator that invokes XOTD generation
- Annotation.hs - Populates the annotation database this module references
- Config.Misc - Related configuration module with global constants
- LinkMetadata.hs - Annotation database used for annotation-of-the-day
- Blog.hs - Related daily content system for blog posts
- sync.sh - Build orchestrator coordinating content generation