Functional programming and non-functional programming

Question

In my second year of University we were \"taught\" Haskell, I know almost nothing about it and even less about functional programming.

What is functional programming

Answer 1

I prefer to use functional programming to save myself repeated work, by making a more abstract version and then using that instead. Let me give an example. In Java, I often find myself creating maps to record structures, and thus writing getOrCreate structures.

SomeKindOfRecord getOrCreate(T thing) { 
    if(localMap.contains(thing)) { return localMap.get(thing); }
    SomeKindOfRecord record = new SomeKindOfRecord(thing);
    localMap = localMap.put(thing, record);
    return record; 
}

This happens very often. Now, in a functional language I could write

RT getOrCreate(T thing, 
                  Function> thingConstructor, 
                  Map> localMap) {
    if(localMap.contains(thing)) { return localMap.get(thing); }
    RT record = thingConstructor(thing);
    localMap = localMap.put(thing,record);
    return record; 
}

and I would never have to write a new one of these again, I could inherit it. But I could do one better than inheriting, I could say in the constructor of this thing

getOrCreate = myLib.getOrCreate(*,
                                SomeKindOfRecord.constructor(), 
                                localMap);

(where * is a kind of "leave this parameter open" notation, which is a sort of currying)

and then the local getOrCreate is exactly the same as it would have been if I wrote out the whole thing, in one line, with no inheritance dependencies.