I want to type "--> " and have it automatically converted into "→ ". Is there a way to do this using Abbrev?
From emacs manual:
More precisely, any character that is not a word constituent expands an abbrev, and any word-constituent character can be part of an abbrev.
So the answer is no because characters '-' and '>' are not word characters.
Instead, do come up a with naming schema that is easy to remember. I am using the convention from Xah Lee to start Unicode abbrevs with character 8 and use a short mnemonic string. For example, add this into your global-abbrev-table:
("8ar" "→" nil 0)