gnu: Add r-plumber.

* gnu/packages/cran.scm (r-plumber): New variable.

gnu/packages/cran.scm

@@ -2505,6 +2505,40 @@ (define-public r-plotfunctions
 with default R plot functions.")
     (license license:gpl2+)))
 
+(define-public r-plumber
+  (package
+    (name "r-plumber")
+    (version "1.2.1")
+    (source (origin
+              (method url-fetch)
+              (uri (cran-uri "plumber" version))
+              (sha256
+               (base32
+                "1k0y7ylc8bld16imn86g0i0dmxmr3kmh9ax4ys0yrxqzrvji7z3g"))))
+    (properties `((upstream-name . "plumber")))
+    (build-system r-build-system)
+    (propagated-inputs (list r-crayon
+                             r-ellipsis
+                             r-httpuv
+                             r-jsonlite
+                             r-lifecycle
+                             r-magrittr
+                             r-mime
+                             r-promises
+                             r-r6
+                             r-rlang
+                             r-sodium
+                             r-stringi
+                             r-swagger
+                             r-webutils))
+    (home-page "https://www.rplumber.io")
+    (synopsis "API generator for R")
+    (description
+     "This package gives you the ability to automatically generate and serve
+an HTTP API from R functions using the annotations in the R documentation
+around your functions.")
+    (license license:expat)))
+
 (define-public r-polychrome
   (package
     (name "r-polychrome")