

Is Joe Armstrong kidding? - navium
https://pragprog.com/titles/jaerlang2/errata

======
navium
If you check the errata #77244, that's his ONE SINGLE example of how you can
use pattern matching with maps. I smiled as I read the example. But when I
tried it, boom! That piece of code does not run on any released version of
Erlang, and I am here trying out Erlang to see if I can use it in my
enterprise project! The most disappointed I have been while learning any
language.

~~~
fenollp
Yes, the line

    
    
        count_characters([H|T], #{ H := N }=X) -> …
    
    

is not yet fully understood by the VM. More details on this here [1]. Every
other line works fine though. Oh and instead of using maps one can use
records, dicts, sets, gb_trees, proplists, …

[1] [http://stackoverflow.com/questions/23106543/illegal-
pattern-...](http://stackoverflow.com/questions/23106543/illegal-pattern-in-
map-of-erlang)

~~~
navium
Agree. But that line is the crux! They should have implemented this match to
begin with, to functionally make use of maps!

