allow showing NUON diffs

.gitattributes

@@ -0,0 +1 @@
+*.nuon diff=nuon

scripts/print-nuon.nu

@@ -0,0 +1,31 @@
+#!/usr/bin/env nu
+
+def main [file: path]: [ nothing -> string ] {
+    if not ($file | path exists) {
+        error make {
+            msg: $"(ansi red_bold)file_not_found(ansi reset)",
+            label: {
+                text: "no such file",
+                span: (metadata $file).span,
+            },
+            help: $"`($file)` does not exist",
+        }
+    }
+
+    let content = open --raw $file
+
+    let data = try {
+        $content | from nuon
+    } catch {
+        error make {
+            msg: $"(ansi red_bold)invalid_nuon(ansi reset)",
+            label: {
+                text: "could not parse NUON",
+                span: (metadata $file).span,
+            },
+            help: $"`($file)` does not appear to be valid NUON",
+        }
+    }
+
+    $data | to nuon -i 4
+}

toolkit.nu

@@ -16,3 +16,8 @@ export def print-nupm-env [] {
     print $'PATH: ($env.PATH?)'
     print $'NU_LIB_DIRS: ($env.NU_LIB_DIRS?)'
 }
+
+# turn on pretty diffs for NUON data files
+export def set-nuon-diff [] {
+    git config diff.nuon.textconv (pwd | path join scripts print-nuon.nu)
+}