In SWI Prolog, list(Xs) :- length(Xs, _). is "pure" in that I can pass it a variable with any sort of instantiatedness and it will nondeterministically unify it with all most general unif...

I was looking through the Mercury programming language's about page when I found a part where it said: Mercury is a strongly moded language What does this mean!? I've search all over the internet...

So I started to wrap my head around Monads (used in Haskell). I'm curious what other ways IO or state can be handled in a pure functional language (both in theory or reality). For example, there is...

I noticed that in Rust moving is applied to lvalues, and it's statically enforced that moved-from objects are not used. How do these semantics relate to uniqueness typing as found in Clean and Mer...

I was wondering about a Prolog that could include a built-in call like this: accum(generator, filter, accumulator) Calculates all solutions to generator. For each one, if filter can be proved, acc...

I've starting looking at the Mercury language, which seems very interesting. I'm a new to logic programming, but pretty experienced with functional programming in Scala and Haskell. One thing I've ...

I would like to ask you about what formal system could be more interesting to implement from scratch/reverse engineer. I've looked through some existing and open-source projects of logical/declar...