Fiber Web API Interop Demo

A JSON REST API built with Fiber and Gloat, demonstrating Go/Clojure interoperability for web applications.

make serve

This installs all dependencies (Go, Gloat, Glojure) locally via Makes, compiles the Clojure handlers to Go, builds the binary, and starts the server on port 3000.

# Health check
curl localhost:3000/health

# Add items
curl -X POST -d '{"name":"milk"}' localhost:3000/api/items
curl -X POST -d '{"name":"eggs"}' localhost:3000/api/items

# List all items
curl localhost:3000/api/items

# Get one item
curl localhost:3000/api/items/1

# Toggle done status
curl -X PUT localhost:3000/api/items/1/toggle

# Delete an item
curl -X DELETE localhost:3000/api/items/1

Fiber is a Go web framework inspired by Express. It requires Go handler functions with the signature func(*fiber.Ctx) error.

Glojure (the Clojure-to-Go compiler underlying Gloat) does not support deftype or reify, so there is no way to implement a Go interface or pass a Clojure function directly as a Go callback.

The solution splits responsibilities across two files:

handlers.clj -- Pure functional Clojure containing all request logic:

• Each handler receives a request map (:method, :path, :body, :id, etc.) and returns a response map (:status, :body)
• JSON encoding/decoding happens inside Clojure via ys.json
• State is managed with Clojure atoms (in-memory, no persistence)

shim.go -- A Go shim that:

• Creates a Fiber app and registers routes
• For each route, wraps a Clojure handler function: builds a request map from fiber.Ctx, invokes the handler, and extracts :status (int64) and :body (string) from the response map
• Go never inspects the JSON payloads -- they stay as strings serialized by ys.json/dump inside Clojure

The key design choice is where JSON serialization happens. By doing it inside Clojure (using ys.json/dump and ys.json/load), the Go shim only needs to extract two simple values from the Clojure response map: an integer status code and a string body. Go never walks Clojure persistent data structures.

1. gloat --module=... handlers.clj -o build/ compiles the Clojure handlers to a Go module directory with a generated main.go
2. The generated main.go is replaced with shim.go (with the module path substituted in)
3. Fiber is added to go.mod, then go mod tidy && go build produces the binary