Show HN: You can program without loop and recursion and×÷- is all you need (opens in new tab)

(github.com)

9 pointsraoof1y ago17 comments

17 comments

7 comments · 3 top-level

rstuart41331y ago· 1 in thread

Why over complicate it? FRACTRAN is a Turning complete language based on only one operation: multiplication. It's Wikipedia entry gives a short FRACTRAN program that finds all primes. https://en.wikipedia.org/wiki/FRACTRAN

In the words of it's inventor, John Conway:

    Makes workday really easy!  FRACTRAN needs no complicate programming manual. It's entire syntax can be learned in 10 seconds, and programs for quite complex and interesting functions can be written almost at once.  The entire configuration of a FRACTRAN computer at any instant is a single integer - no messy "tapes" or other foreign concepts to be understood by the fledging programmer.

What's not to like? This is a good introduction for someone seriously considering doing their next project in FRACTRAN: https://raganwald.com/2020/05/03/fractran.html

raoofOP1y ago

FRACTRAN has a goto instruction so it is not a total model of computation but my claim is that Ar is a total model of computation. maybe unrolled FRACTRAN is a total model of computation too, I have to think about that

voidUpdate1y ago· 3 in thread

How do you go back to an earlier point in the program if you can't loop? For example, how would you do a primality test for an arbitrary input?

raoofOP1y ago

if you don't want to melt your brain :D you just precompute the value of any functions f(x) for x<n otherwise you need to be very clever I explained my idea in the link

out_of_protocol1y ago

Don't need a language then, just compile down to "return 4". No instructions needed. Without user input it's not really useful. How about returning maximum value of user-privided array of int64 values? If array is static, just return final value and that's all. Smart compiler for the win!

P.S. precomputing even a single int64 space is going to be really really hard, 2^64 possible values is a lot

1 more reply

voidUpdate1y ago

That's why I said an arbitrary number, you can't just precompute the primality of every single number... And I'm afraid I don't really understand your proof of being able to do loops without any kind of looping construct in the language itself

2 more replies

brudgers1y ago

       Epigram 54.

       Beware of the Turing tar-pit
       in which everything is possible
       but nothing of interest is easy.

j / k navigate · click thread line to collapse

17 comments

7 comments · 3 top-level

rstuart41331y ago· 1 in thread

In the words of it's inventor, John Conway:

    Makes workday really easy!  FRACTRAN needs no complicate programming manual. It's entire syntax can be learned in 10 seconds, and programs for quite complex and interesting functions can be written almost at once.  The entire configuration of a FRACTRAN computer at any instant is a single integer - no messy "tapes" or other foreign concepts to be understood by the fledging programmer.

What's not to like? This is a good introduction for someone seriously considering doing their next project in FRACTRAN: https://raganwald.com/2020/05/03/fractran.html

raoofOP1y ago

voidUpdate1y ago· 3 in thread

How do you go back to an earlier point in the program if you can't loop? For example, how would you do a primality test for an arbitrary input?

raoofOP1y ago

if you don't want to melt your brain :D you just precompute the value of any functions f(x) for x<n otherwise you need to be very clever I explained my idea in the link

out_of_protocol1y ago

P.S. precomputing even a single int64 space is going to be really really hard, 2^64 possible values is a lot

1 more reply

voidUpdate1y ago

2 more replies

brudgers1y ago

       Epigram 54.

       Beware of the Turing tar-pit
       in which everything is possible
       but nothing of interest is easy.

j / k navigate · click thread line to collapse