Added linting to CI workflow (#23)

Customized linting rules on CI (#23)

.github/workflows/r.yml

@@ -96,6 +96,24 @@ jobs:
             covr::codecov()
           shell: Rscript {0}
 
+        # Judging coding style ----------------------------------- #
+        - name: Linting package
+        run: |
+          install.packages("lintr")
+          style_rules <- list(
+            assignment_linter, closed_curly_linter, commas_linter,
+            todo_comment_linter, equals_na_linter,
+            function_left_parentheses_linter, infix_spaces_linter,
+            line_length_linter, no_tab_linter, open_curly_linter,
+            paren_brace_linter, absolute_path_linter, nonportable_path_linter,
+            pipe_continuation_linter, semicolon_terminator_linter,
+            single_quotes_linter, spaces_inside_linter,
+            trailing_blank_lines_linter, trailing_whitespace_linter,
+            undesirable_function_linter, undesirable_operator_linter
+          ) # TODO: expand style rules as package matures
+          lintr::lint_package(linters = style_rules)
+        shell: Rscript {0}
+
         # Uploading check results -------------------------------- #
         - name: Uploading check results
           if: failure()