Comment on I dunno

vala@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

(* (+ 2 5) (+ 2 5))

• yboutros@infosec.pub ⁨11⁩ ⁨months⁩ ago

  Is this a meme? Shouldn’t it be

  ( + 2 ( * 5 ( - 8 5 ) ) )
  

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  • vala@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

    Damn you are right haha.

    Mine evals to 21.

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• merc@sh.itjust.works ⁨11⁩ ⁨months⁩ ago

  So, if 2 5 8 5 - × + is “RPN” does that mean that the LISP version is Polish Notation?

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• Reginald_T_Biter@lemmy.world ⁨11⁩ ⁨months⁩ ago

  Explain yourself sir

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  • vala@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

    This is called “prefix notation”. The operator comes before the operands and every expression goes in parentheses.

    For instance you could write:

    (+ 1 2 3 4)
    

    Which would evaluate to 10.

    This syntax is from a family of programming languages usually called LISP.

    en.wikipedia.org/…/Lisp_(programming_language)

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    • merc@sh.itjust.works ⁨11⁩ ⁨months⁩ ago

      Also, you can use this for more than just arithmetic. The first thing in the list is the name of the function, and everything else is something that you pass to the function. So you could instead write

      (plus 1 2 3 4)
      

      Which would be like plus(1, 2, 3, 4) in other kinds of programming languages.

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    • Reginald_T_Biter@lemmy.world ⁨11⁩ ⁨months⁩ ago

      Awesome thanks for explaining that. That’s cool as hell.

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    • call_me_xale@lemmy.zip ⁨11⁩ ⁨months⁩ ago

      I understand prefix notation, but you got the order of operations wrong…

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      • vala@lemmy.dbzer0.com ⁨11⁩ ⁨months⁩ ago

        Yeah I’m stupid

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