print usage

Author: behrica

src/libpython_clj2/python/uv.clj

@@ -57,16 +57,38 @@
       (dorun (char-seq err-rdr)))))
 
 
+(defn- uv-installed? []
+  (try
+    (let [p (process/start  "uv" "--version")]
+      ;; We only need to know it starts; stop it quickly.
+      (.destroy ^Process p)
+      true)
+    (catch java.io.IOException _
+      false)
+    (catch Throwable _
+      false)))
+
 (defn sync-python-setup! 
-  "Synchronize python venv at .venv with 'uv sync'."
+  "Synchronize python venv at .venv with 'uv sync'.
+  When 'uv' is not available on PATH, throws with guidance to install."
   []
   (println "Synchronize python venv at .venv with 'uv sync'. This might take a few minutes")
+  (when-not (uv-installed?)
+    (println "The 'uv' tool was not found on your PATH.")
+    (println "Install uv from https://github.com/astral-sh/uv, e.g.:")
+    (println "  - curl -LsSf https://astral.sh/uv/install.sh | sh")
+    (println "  - or: pipx install uv")
+    (throw (ex-info "The 'uv' tool is not installed or not on PATH." {:tool "uv" :stage :preflight})))
   (let [deps-edn
-        (->
-         (slurp "python.edn")
-         edn/read-string)]
+        (try
+          (-> (slurp "python.edn") edn/read-string)
+          (catch java.io.FileNotFoundException e
+            (throw (ex-info "Missing python.edn. Copy python.edn.example to python.edn and set :python-version and :python-deps."
+                            {:file "python.edn" :stage :read-config} e))))]
     (write-pyproject-toml! deps-edn)
-    (start-and-print! ["uv" "sync" "--python" (-> deps-edn :python-version)])))
+    (start-and-print! ["uv" "sync" "--python" (-> deps-edn :python-version)])
+    (println "Python environment synchronized with uv.")
+    true))