sexpmachine

Find repeating s-expression patterns in Clojure codebases.

Analyzes .clj, .cljc, and .cljs files to identify duplicated code patterns that might benefit from refactoring into shared functions or macros.

Installation

Requires Babashka and bbin.

bbin install io.github.Ralii/sexpmachine

Usage

sexpmachine <directory> [min-size] [min-frequency] [options]

Arguments:
  directory      Directory to analyze (required)
  min-size       Minimum expression size in nodes (default: 3)
  min-frequency  Minimum occurrences to report (default: 5)

Options:
  --no-calls           Exclude function/macro calls from results
  --no-keyword-chains  Exclude keyword-heavy expressions (maps, get-in paths, etc.)
  --help               Show this help message

Examples

Analyze a project with default settings:

sexpmachine src

Find patterns with at least 4 nodes that appear 3+ times:

sexpmachine src 4 3

Exclude function calls to focus on data patterns:

sexpmachine src 3 2 --no-calls

Exclude keyword-heavy expressions (get-in paths, keyword maps, etc.):

sexpmachine src 3 2 --no-keyword-chains

Example Output

Analyzing . (min size: 4 , min frequency: 3 , excluding calls)
---

Pattern: {:color :blue}
  Size: 4 nodes
  Found 8 times:
    - src/components/button.clj :35
    - src/components/button.clj :36
    - src/components/card.clj :55
    - src/views/dashboard.clj :7
    - src/views/dashboard.clj :11
    - src/views/settings.clj :7
    - src/views/settings.clj :8
    - src/views/settings.clj :12

Pattern: {:class "container"}
  Size: 4 nodes
  Found 7 times:
    - src/components/layout.clj :34
    - src/components/layout.clj :53
    - src/views/home.clj :6
    - src/views/home.clj :10
    - src/views/about.clj :6
    - src/views/about.clj :11
    - src/views/about.clj :15

How It Works

sexpmachine uses rewrite-clj to parse Clojure source files into ASTs. It then:

1. Recursively collects all sub-expressions from each file
2. Calculates expression size (number of nodes)
3. Groups identical expressions across the codebase
4. Reports patterns that meet the minimum size and frequency thresholds

The "size" metric counts all nodes in an expression, including nested structures. For example:

• x = 1 node
• [a b] = 3 nodes (vector + 2 symbols)
• {:a 1} = 4 nodes (map + map-entry + key + value)

License

MIT