[GitHub] [arrow] thisisnic commented on a diff in pull request #14361: ARROW-13766: [R] Add slice_*() methods

[GitBox <gi...@apache.org>]

thisisnic commented on code in PR #14361:
URL: https://github.com/apache/arrow/pull/14361#discussion_r992300613


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r/R/expression.R:
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@@ -173,7 +173,12 @@ Expression$create <- function(function_name,
   assert_that(is.string(function_name))
   assert_that(is_list_of(args, "Expression"), msg = "Expression arguments must be Expression objects")
   expr <- compute___expr__call(function_name, args, options)
-  expr$schema <- unify_schemas(schemas = lapply(args, function(x) x$schema))
+  if (length(args)) {
+    expr$schema <- unify_schemas(schemas = lapply(args, function(x) x$schema))
+  } else {
+    # TODO: this shouldn't be necessary
+    expr$schema <- schema()
+  }

Review Comment:
   Just to check, what's the reason for this change?



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