Maple 18, document mode. Please try this:

>restart;
>some_long_name:=3:
>f(som)

Now, as the cursor is right after the "m" above, hiting the ESC key to autocomplete, nothing happens. Only a beep, meaning Maple does not know about the variable name I wanted to expand to, which is "some_long_name". What I do now is manually add a space by  pushing the ")" away, like this:

  f(som )

And now put the mouse back in front of the "m" and now hit ESC. Maple now can see the name I wanted.

Really? This is very bad design. You might ask, why did I close the () first? Well, I like to start by writing () then fill it in, or it can be that I am changing things, and wanted to write a new name, and the () was allready there. I use name autocomplete alot, and it is very annoying to not be able to use it if happens that there is a ")" or "]" right next to the name.

Having to keep pushing the ")" away, so that Maple can see the name makes no sense since ")" can't part of a name.

In Mathematica it just works. I can do

someLongName = 3;

Then in a new cell,

f[som] and hit CTRL-K  when mouse at the letter "m" just typed it in, and it will autocomplete.  I did not have to push "]" away first.

Please Maple, fix your user interface so it is less awkward and annoying to use. This is version 18 of the software, and not version 1.