Jura SSG

Static site generator in J.

Why J for Static Sites?

J is an array programming language where transformations apply to entire structures at once. Static site generation is fundamentally data transformation: content files become HTML pages. J treats this as a natural array operation.

Who This Is For

• Array programming enthusiasts who want site generation expressed as composition

• APL-family practitioners seeking modern tooling integration

• Minimalists who appreciate that a complete SSG fits in kilobytes

• Data transformation experts who see content as vectors to reshape

Core Properties

Tacit Composition

Pipelines build from verbs without naming intermediate values:

render =: emit @ template @ parse @ read

Content flows right-to-left through composed functions. No variables, no state—just transformation.

Rank Polymorphism

Operations automatically extend across array dimensions:

NB. render works on one file or a thousand
render 'post.md'
render posts

The same verb handles a single page or an entire site. Rank determines how deeply the operation penetrates.

Extreme Density

J programs are measured in characters, not lines:

toc =: ('#'&=@{. # ])&.>

A complete table-of-contents extractor in 23 characters. Every glyph carries meaning.

Fork and Hook

Function trains create branching pipelines:

NB. Fork: apply three verbs, combine results
slug =: tolower @ alphanum @ title

NB. Hook: feed result back as right argument
dated =: ,&'/'&date

Complex transformations emerge from simple verb combinations.

Technical Guarantees

Property	Mechanism
Deterministic output	Pure functional transforms
Parallel rendering	Implicit array operations
Memory efficiency	In-place mutation where safe
No runtime surprises	Total functions on boxed arrays

Architecture

┌─────────┐    ┌─────────┐    ┌──────────┐    ┌────────┐
│ content │───▶│  parse  │───▶│ template │───▶│  emit  │
│  files  │    │  (;:)   │    │   (@.)   │    │  (1!:) │
└─────────┘    └─────────┘    └──────────┘    └────────┘
     │              │              │              │
     └──────────────┴──────────────┴──────────────┘
                    rank polymorphic

Each stage is a verb. The pipeline is their composition. J’s rank operator controls iteration depth automatically.

Features

• Incremental builds via file modification time filtering

• Parallel page generation through implicit array operations

• Hot reload with filesystem watching

• Markdown and AsciiDoc content parsing

• Template composition using gerunds and agenda

Integration

Jura SSG participates in the poly-ssg-mcp ecosystem, providing MCP tools for Claude integration:

• jura_init — scaffold a new site

• jura_build — generate static output

• jura_serve — local development server

• jura_watch — incremental rebuilds

The ReScript adapter bridges J execution to the MCP protocol.

Installation

Requires J 9.4+ from Jsoftware.

# Clone and install addons
git clone https://github.com/hyperpolymath/jura-ssg
cd jura-ssg
jconsole -js "install'web/jura'"

License

AGPL-3.0-or-later