Idiomatic Erlang?

[Benjamin Scherrey]

Been a couple of decades since I did any Erlang coding from scratch and it
seems to have improved significantly (didn't have proper strings back then
for example). I have a little hobby project I'm using to get myself up to
snuff so I can do some more serious work for an upcoming project. Would
appreciate some feedback regarding a few issues/questions. The code can be
found at https://github.com/scherrey/dnderl .

If you've ever played Advanced Dungeons & Dragons you'll recognize that
this is a simple implementation of the THAC0 (to-hit armour class 0)
concept from the original combat tables in the Dungeon Masters Guide.
So 'combat:thac0(fighter,
5, 2).' would correctly tell you that your 5th level fighter needs to roll
a 14 or higher on a 20-sided die to hit an armour class 2 opponent
whereas 'combat:thac0(thief,
5, 2).' would tell you that a similar level thief requires a roll of 17 or
better. Here are my questions:

1) My top level module is combat.erl (
https://github.com/scherrey/dnderl/blob/master/combat.erl ). All it really
does is introduce the class atom type and re-export
combattables:basetohit/3 (albeit under a different name, thac0/3). Is it
necessary to create a forwarding function like thac0/3 like I'm doing when
I'd really just prefer to establish thac0/3 in the combattables module and
re-export it from combat.erl? (Don't read anything into the different names
- I just decided to rename it in the top level module because I liked it
better and would be happy to use that same name throughout.) Attempting to
re-export a function declared in another module gives me an error.


2) In combattables.erl (
https://github.com/scherrey/dnderl/blob/master/combattables.erl ) I put
monster_offset/1 as its own function because I couldn't figure out syntax
for how to get the result of the if statement as an intermediate variable
which I would have put inside the last basetohit/3 implementation. I tried
several things but nothing that seemed correct to me would compile so I had
to break it out into its own function. I feel like I'm missing something
obvious but perhaps it's simply not allowed?


3) Is the way I've overloaded basetohit/3 with guards depending on which
class is passed in the preferred idiomatic way to implement such a
construct in Erlang? I thought of trying 'case' or 'if' but this seemed
"cleanest" to me. I generally avoid if statements whenever possible in my
other programming languages like C++ & Python. Appreciate any insights for
such circumstances.


4) Is there no such thing as a module scope for a variable in Erlang? In
combattables.erl I have 4 functions that return tuples representing the
combat tables for each class. My initial thought was that they would be
variables that could be referenced by any function in the module but that
doesn't seem to work. The tuples in this case are constant lookup tables
not to be updated. Am I doing this in the "correct" idiomatic manner for
Erlang?


thanks & best regards,

 -- Ben Scherrey
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