That match specifications can be built using ets:fun2ms(...) where the Erlang fun syntax is used and translated into a match specification with a parse transform.
1> ets:fun2ms(fun({Foo, _, Bar}) when Foo > 0 -> {Foo, Bar} end).
[{{'$1','_','$2'},[{'>','$1',0}],[{{'$1','$2'}}]}]
So no fun-value is ever built, the expression gets replaced with the match-spec at compile-time. The fun may only do things a match expression could do.
Also, ets:fun2ms is available for usage in the shell, so fun-expressions can be tested easily.
