Regular expression - no capture for negative character class

Question

I am trying to write different sed scripts for beautifying ruby code. One of the cases i am trying to solve is to replace a=>b or a=> b strings with a => b. The regex for matching this condition is [^ ]=> but it also matches 1 character before =>. So, when i try to replace it is not giving me the desired result with s/[^ ]=>/ =>/g

Any suggestions?

Answer 1

You need to use a capture:

s/\([^ ]\)=>/\1 =>/g

Answer 2

How about replacing both sides unconditionally?

s/ ?=> ?/ => /g