Literals in Programming Languages

This article is only about primitive literals, not compound ones. I think the list and dict literals in Python are the #1 reason I like it better than C. I think the regexp literals in Perl were one of the main reasons people liked Perl better than C.

mahmud2• 13 years ago

That line blurs when you have homoiconic syntax, specially one with a programmable reader. Common Lisp uses the # for dispatch macro character, you can define your own literals, in whatever environment you want.

http://www.franz.com/support/documentation/6.2/ansicl/subsec...

arethuza• 13 years ago

Can't you set any dispatch character you like using make-dispatch-macro-character ?

pilgrim689• 13 years ago

> I like [Python] better than C

Isn't it strange to compare Python/Perl to C and say that one is better than the other? It's apples to oranges. You wouldn't use Python or Perl to build an OS, and you wouldn't use C to prototype a web app.

jmmcd2• 13 years ago

Sure, but I said "like", not "better". When I learned Python, I had that feeling described as weightlessness by xkcd [http://xkcd.com/353/], because I didn't have to write several lines and a loop to make a list. It made me happy. Fair comparisons don't really come into it.

masklinn• 13 years ago

> This article is only about primitive literals, not compound ones.

It mentions array literals: http://www.gavilan.edu/csis/languages/literals.html#_Toc7587...

DerekL• 13 years ago

C99 has array and struct literals:

  (int []) { 1, 2, 3 }
  (struct Point) { 3, 5 }
  (struct Point) { .x = 3, .y = 5 }

anders02• 13 years ago

To nitpick, -14 isn't a literal in all languages. :)

(In Haskell, it's just sugar for negate 14, while in Standard ML it's spelt ~14. And I assume there are other exceptions too.)

pdw• 13 years ago

Even in C it's not a literal. The consequence is that in a 32-bit implementation, you can't write INT_MIN as -2147483648 (-2^31), because 2147483648 would overflow a signed int. Instead a workaround such as -2147483647-1 must be used.

anders02• 13 years ago

Huh. I always assumed it was in C. Shows what I know… :p

shaurz• 13 years ago

Making the minus part of the literal can lead to parsing ambiguity. For example, "x-3" would parse as 2 tokens "x" and "-3" (instead of 3 tokens "x", "-" and "3") which would be a syntax error in C. The only workaround I can think of is making any expression followed by a negative number parse as a subtraction.

swah• 13 years ago

Factor has them for many data-structures: http://docs.factorcode.org/content/article-syntax-literals.h..., but they are simple to add in a concatenative language

(they might as well have been added by a user library).

Literals in Programming Languages

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