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And what do you think about operator precedences? Would be harder programming in language where the operations are executed in sequential order?

Ex.:

2 + 3 * 4 == 20

2 + (3 * 4) == 24

Ok, Lisp family has not precedences by definition. Let's gonna talk about procedural and object oriented languages using this "feature".

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It would be a strange language indeed that doesn't have operator precedence that isn't generally the same as found in classical mathematics. – greyfade Sep 14 '10 at 2:25
This doesn't seem off topic to me. Is there a reason you decided to close your own question? – Macneil Nov 25 '10 at 5:24
@Macneil: It's objective and can be ask on Stackoverflow. – bigown Nov 25 '10 at 9:02
I reopened it in effect to close this proposal: area51.stackexchange.com/proposals/24689/programming-language – bigown Feb 2 '11 at 11:08
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This is a poll type question and I don't see the value in it. It's like asking "which languages don't support parameterized types" – Mike Brown Feb 25 at 23:25

5 Answers

up vote 8 down vote accepted

Smalltalk.

Everything's done with message sending, so 1 + 2 * 3 means "send * with parameter 3 to the object returned by sending the message + with parameter 2 to the object 1".

That throws people (it threw me) because of how we usually write maths, but since I can never remember C's operator precedence I cope in the same manner in both languages - I use ()s to group terms: 1 + (2 * 3).

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up vote 3 down vote

Prolog.

Well, kind've. There are standard operators, with standard precedence... but you can trivially define operators with arbitrary predence, because 1 + 2 is really the goal +(1, 2).

You may define infix (1 + 2), prefix (++X) and postfix (X++) operators, with arbitrary associativity (so left, right or both).

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up vote 4 down vote

LISP-type languages don't need precedence because expressions are fully parenthesized. There is no need for precedence to evaluate

(sqrt (expt (- x1 x2) 2)
      (expt (- y1 y2) 2))

I know J, and I believe it's close relative K (along with their parent language, APL, as noted by @Jerry Coffin), evaluate everything right to left with no precedence.

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Neither prefix notation (as in Lisp languages) nor postfix notation (HP calculators) need operator precedence. It's only infix that needs parentheses. – Frank Shearar Sep 15 '10 at 6:15
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Prefix notation can do away with parentheses only if all operations have fixed arity. In the LISP family, the arithmetic operators can take more than two arguments (or less): (+) -> 0, (* 1 2 3 4) -> 24, etc. – Hoa Long Tam Sep 15 '10 at 14:50
Ah, you got me there! Quite right; I assumed "operator" meant "binary operator" – Frank Shearar Sep 15 '10 at 15:30
up vote 4 down vote

APL has no precedence. If memory serves, everything is evaluated right to left.

Oddly, at least in an official sense, neither C nor C++ has operator precedence. The standard isn't written that way, although (of course) it's mostly a different way of saying the same thing as having precedence. OTOH, it is only mostly the same thing -- ultimately, there's no way to write a precedence table for C or C++ and get everything quite right. There are a few things that just won't quite fit.

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5  
C and C++ both have precedence. It's even a part of the formal grammar. I believe what you're talking about is the order of the evaluations of subexpressions. For example f() + g() * h() in C/C++ can call any of f, g, or h first, but it always computes (the equivalent of) the * happening before the +. – Macneil Oct 29 '10 at 1:02
up vote 4 down vote

Forth

It's (almost) all RPN notation, so no precedence rules needed. I'd wager most languages using postfix or prefix notation (PostScript, Lisp...) would work the same.

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