gnu: Add go-github-com-niemeyer-pretty.

* gnu/packages/golang.scm (go-github-com-niemeyer-pretty): New variable.

Signed-off-by: Raghav Gururajan <rg@raghavgururajan.name>

gnu/packages/golang.scm

@@ -11052,6 +11052,39 @@ (define-public go-github-com-go-test-deep
 when comparing complex types like structures and maps.")
     (license license:expat)))
 
+(define-public go-github-com-niemeyer-pretty
+  (package
+    (name "go-github-com-niemeyer-pretty")
+    (version "0.0.0-20200227124842-a10e7caefd8e")
+    (source (origin
+              (method git-fetch)
+              (uri (git-reference
+                    (url "https://github.com/niemeyer/pretty")
+                    (commit (go-version->git-ref version))))
+              (file-name (git-file-name name version))
+              (sha256
+               (base32
+                "1jmazh4xzaa3v6g46hz60q2z7nmqs9l9cxdzmmscn3kbcs2znq4v"))))
+    (build-system go-build-system)
+    (arguments
+     (list #:import-path "github.com/niemeyer/pretty"
+           #:phases
+           #~(modify-phases %standard-phases
+               (add-after 'unpack 'int-to-string-with-rune
+                 (lambda* (#:key import-path #:allow-other-keys)
+                   (with-directory-excursion (string-append "src/" import-path)
+                     (substitute* "formatter.go"
+                       (("s \\+= string\\(i\\)")
+                        "s += string(rune(i))"))))))))
+    (propagated-inputs (list go-github-com-kr-text))
+    (home-page "https://github.com/niemeyer/pretty")
+    (synopsis "Pretty-print Go values")
+    (description
+     "The pretty package provides pretty-printing for Go values.  This is
+useful during debugging, to avoid wrapping long output lines in the
+terminal.")
+    (license license:expat)))
+
 ;;;
 ;;; Avoid adding new packages to the end of this file. To reduce the chances
 ;;; of a merge conflict, place them above by existing packages with similar