# Do any languages use =/= for the inequality operator?

Wikipedia says:

Not equal

The symbol used to denote inequation — when items are not equal — is a slashed equals sign "≠" (Unicode 2260).

Most programming languages, limiting themselves to the ASCII character set, use ~=, !=, /=, =/=, or <> to represent their boolean inequality operator.

All of these operators can be found in this table, apart from `=/=`. I can find this equals-slash-equals used as a way of formatting ≠ in plaintext but not in any programming language.

Has `=/=` been used as the inequality operator in any programming language?

• It might help if you explain why you care, what problem you're trying to solve. "any programming language" is a pretty wide field; it seems likely that there was some language somewhere in the history of computing that used =/=, but not so likely that a well-known language does. It'd be simple enough to create a language that accepts =/= for not equal, but I don't expect that'd help. So... why do you care, and how is this question constructive? Nov 7, 2011 at 10:51
• It's not used because not only does it require 3 characters instead of 2 (!=) it's also a really ugly way to represent the slashed equals sign. Nov 7, 2011 at 13:27
• Thanks for asking this... I was searching for `/=` in Haskell and just reading the meta description for this page told me what it was. Aug 6, 2013 at 4:07
• @BenBrocka "ugly" is of course subjective. In the long list of attempts to approximate ≠ in ASCII, I'd argue `=/=` may be the clearest on first viewing - and among the most annoying to type forever after. :) I vaguely recall some language that used `#`, which is also not in the Wikipedia table, so I wouldn't assume the latter to be exhaustive. Mar 9, 2016 at 12:49

Yes, it is in Erlang. `=/=` means exactly not equal to, that would be somewhat equivalent to `!==`.
See more subtle differences (such as `=<` instead of `<=`) here: http://www.erlang.org/doc/reference_manual/expressions.html#id198443
• So all erlang code is sad `=<` `>=` everyone else's is happy `<=` `=>` Nov 7, 2011 at 22:47
In the long list of languages that don't use `=/=`, PROLOG uses `X =\= Y` as "the values `X` and `Y` are not equal", as opposed to the equality operator `=:=`. (Equality, not to be confused with the unification operator `=`!)