[erlang-questions] Design methodology going from Object oriented to functional programming?
Mon Oct 22 14:47:44 CEST 2007
I am trying to understand what is the design process (intellectual,
that is) when building a program in Erlang.
Indeed, in the object oriented world, I would start by finding what
my classes might be and the relationship between them. Gradually I
would add functions (class or instance methods) to the classes in
order to provide solid foundations on top of which I can write an
For example, I could have PERSON, PROFILE, ROLE, FEATURE, etc... and
decide a PROFILE is a collection of FEATURES. A PERSON can have 0 or
many ROLES. A ROLE is a PROFILE on a given area (a department for
example) for a given time. I would then add functions such as "give
all the active roles for the user" or "what features give that
profile" or "does the user have a given feature for that department".
I admit it is more complexe than that, but you get the idea.
Obviously, this doesn't seem to be the way to go with Erlang.
Intuitively, I would start making a list of all the functions which
will allow me to interract with my application. In that case I could
have "give me all users with an active role on that department",
etc... Then by implementing those high level functions I would split
them into pieces by calling smaller simpler functions. The underlying
data structure will "just follow" or "appear" naturally.
Hence: object oriented design is "data structure and relationships
first, functions second" and functional design is "functions first,
data structure second".
Am I being over simplistic here. Are there some guidelines as to how
one can approach a problem when creating a new program? Especially
programs which deal with persistent data, not protocole analysers or
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