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https://github.com/xtuc/fibonacci-forth

The Fibonacci sequence using Forth language with only two words
https://github.com/xtuc/fibonacci-forth

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The Fibonacci sequence using Forth language with only two words

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# Fibonacci-forth
The Fibonacci sequence using Forth language

I used GNU Forth (https://www.gnu.org/software/gforth).

## Explanations

Forth is a stack based language. All functions are called words.

* `2dup` word duplicates `n` and `n-1` elements and put it on the top of the stack
* `+` word takes `n` and `n-1` elements from the stack and sum them. The result goes on top of the stack.

```forth
: fib ( x1 x2 -- x1 x2 x3 )
2dup
+
;
```

The `fib` word sums the two last elements and put the result on the top of the stack, which is the Fibonacci sequence.

## Result

First number is the occurrence of the sequence and the second its result.

![result](.github/result.png)