Porting here document

README.md

@@ -16,19 +16,23 @@ The only dependency is the ruby builtin regex engine, MRI 2.0+ should work.
 
 2. renamed the extension `.rb` to `.cr` for files will in-place use this script.
 
-3. run bin/port_ruby_to_crystal, this will do replace on known rules. if it give some error messages,
-   just fix it manually, until no any error.
+3. run bin/port_ruby_to_crystal, this will do in replace all "*.cr" use known rules.
+   You bet added those files into git before do it to track changes.
+
+4. if it give message like `syntax error in '???': ...`, this may be a bug of the script
+   making the wrong substitution, Or it's just not covered by the rules.
+   for this case, you need fix it manually, until no any error.
 
 ```sh
-$ cd you_project_root
-$: path/to/port_ruby_to_crystal
+$: cd you_project_root
+$: port_ruby_to_crystal
 ```
 
 This project can also be used as a learning resource to see exactly what Ruby APIs are different with Crystal, just check the diff of `./test/test.rb` with `./test/test.cr`.
 
 ## Why not replace `[]` to `[] of SomeType`, `{}` to `{} of SomeType => SomeType`, it's really annoying of those syntax error.
 
-There is no good default SomeType for this case, following is a good [advice](https://forum.crystal-lang.org/t/is-there-exists-a-dart-dynamic-type-equivalent-for-crystal-or-equivalent-usage/5082/8?u=zw963)
+There is no good default SomeType for this case, following is a good [advice](https://forum.crystal-lang.org/t/is-there-exists-a-dart-dynamic-type-equivalent-for-crystal-or-equivalent-usage/5082/8?u=zw963), you can replace all unkown type to `BlackHole`, make formatter check pass, then figure the correct type out.
 
 # Contributing
 

bin/port_ruby_to_crystal

@@ -33,6 +33,7 @@ def replace(code)
   code.gsub!(/\b\.strftime(?:\(|\s+)(?:"|')(.+?)(?:"|')\)?/, '.to_s("\1")')
   code.gsub!(/\.delete_suffix\b/, '.rstrip')
   code.gsub!(/\.delete_prefix\b/, '.lstrip')
+  # code.gsub!(/\.freeze\b/, '')
   code.gsub!(/\$stdin\b/, '\1STDIN')
   code.gsub!(/\$stdout\b/, '\1STDOUT')
   code.gsub!(/\$stderr\b/, '\1STDERR')
@@ -41,6 +42,7 @@ def replace(code)
   # so replace rm_f into rm_rf for now
   code.gsub!(/\bFileUtils.rm_f\b/, 'FileUtils.rm_rf')
   code.gsub!(/\balias\s+([\w?!]+)\s+([\w?!]+)\b/, 'def \1; \2; end')
+  code.gsub!(/<<~([A-Z_]+)/, '<<-\1')
 end
 
 if ARGV[0] == '--test'

test/test.cr

@@ -78,3 +78,9 @@ def aaa
 end
 def bbb; aaa; end
 bbb
+
+x = <<-XML
+<parent>
+  <child />
+</parent>
+XML

test/test.rb

@@ -78,3 +78,9 @@ def aaa
 end
 alias bbb aaa
 bbb
+
+x = <<~XML
+<parent>
+  <child />
+</parent>
+XML