Simple hash table implementation

[certik]

@Ashok

There used to be person with profile name “difference scheme” who is a strong supporter of Fortran OO’s superiority. What happened to his profile and posts ? He posted a lot on
https://fortran-lang.discourse.group/t/oo-capabilities-of-fortran-2018-vs-c/1076?u=ashok

He asked me to delete his account (which deletes his posts). I tried to convince him to stay, but he insisted, so I respect that. “difference scheme”, if you are reading this, you are welcome to come back anytime.

@Ashok

Moreover I have one question - forgive me if it is wrong.
Why are we trying to implement data structures like Hash tables, Trees … in Fortran? These are already implemented in C and can be easily implemented in C. Why to do them in Fortran, when Fortran is interoperable with C? Why not exploit that feature (interop with C) for data structures and algorithms in stdlib ? If python people thought they would code entire Numpy and Scipy in Python, now there would be none of them. So why not code the data structures in C and provide a Fortran interface.

I am sorry if my idea is a flawed one - but just expressing my thoughts. May be I am not getting interop with C around my head !

I think languages have to interoperate, and Fortran must interoperate well with other languages and make it easy to use code not only from C, but also C++, Python and others languages.

I think there are two issues with regards to hash tables:

• Having this capability in the first place: For that, indeed we can either implement in Fortran or another language and expose. It needs to be well supported and stdlib seems like a good place for this. It does not require to modify the language, nor include this in the language itself.

• Nice syntax: that would require to modify the language. In some sense this is orthogonal to the previous point. I think we should first concentrate on the previous point before trying to tackle this one.