Am Samstag 15 August 2009 19:06:42 schrieb Daniel Bastos:
In article <200908151831.14649.daniel.is.fischer@web.de>,
Daniel Fischer wrote:
The plus3 example is a "closure" which is hardcoded and available at compile time. I think, to say that a language allows closures means it allows closures determined at run time.
Hm. But does Haskell allow me to define a function at run time? I know Lisp can, since a function is just a data structure which we can put together at run time. But how about Haskell?
Depends on how you interpret it. In the sense of ... let foo = \y -> f x y in map foo list where the value of x is supplied at run time (and more complicated constructions depending on run time values), sure. If you write a good parser, you can also do putStrLn "Please enter function code:" code <- getLine let fun = parseFunction code use fun -- may segfault if the entered code isn't good In which (other) ways can you construct functions at run time in Lisp?