Expose package version info (#625)

* Expose package version info

* Respond to review

crates/ark/src/modules/positron/package.R

@@ -21,6 +21,29 @@
 #' @export
 .ps.rpc.is_installed <- .ps.is_installed
 
+# Returns a list containing:
+#   * the version string if the package is installed and NULL otherwise
+#   * a logical indicating if package is installed at or above the minimum version
+#  This may seem weird, but it's impractical for positron-r to do version
+#  comparisons.
+#' @export
+.ps.rpc.packageVersion <- function(pkg, minimumVersion = NULL) {
+    installed <- system.file(package = pkg) != ""
+
+    if (installed) {
+        version <- utils::packageVersion(pkg)
+        list(
+            version = as.character(version),
+            compatible = is.null(minimumVersion) || version >= minimumVersion
+        )
+    } else {
+        list(
+            version = NULL,
+            compatible = FALSE
+        )
+    }
+}
+
 #' @export
 .ps.rpc.install_packages <- function(packages) {
     for (pkg in packages) {