5 ms·

I think a big thing for many is the lambda: syntax, as well as the lack of full anonymous functions.

• NegativeLatency 10y ago
  I agree that typing out the word lambda is annoying, but you can use them as fully anonymous functions.
  • masklinn 10y ago
    > you can use them as fully anonymous functions. A lambda can only contain a single expression, by "full anonymous function" I'm guessing hexane360 means multiple statements. You can't put a for loop or a context manager in a lambda for instance.
    • grondilu 10y ago
      You can nest lambdas to get the equivalent of several expressions. I once wrote a Runge-Kutta example on Rosetta Code showing this: http://rosettacode.org/wiki/Runge-Kutta_method#using_lambda http://rosettacode.org/wiki/Runge-Kutta_method#using_lambda It does not look as bad as one might expect, though the nesting of parenthesis makes things messy.
      • masklinn 10y ago
        You can but you still can't get statements in there.
        • ergl 10y ago
          You can hack together multiple expressions chaining them with and http://sigusr2.net/one-line-echo-server-using-let-python.html http://sigusr2.net/one-line-echo-server-using-let-python.htm...
          • zardeh 10y ago
            That still doesn't get you statements. You can't get context managers or exception handling (although you can raise exceptions) into lambdas, I've tried.
            • masklinn 10y ago
              Well you might be able to if you add a bunch of named function combinators wrapping these, but definitely not with only lambdas, unless you define your combinators using `ast`, which I think would let you define statements via expressions.
              • AnkhMorporkian 10y ago
                That's an awful lot of effort to go to to avoid naming a function.
              • zardeh 10y ago
                Well sure, you could do something like def apply_ctx(ctx, func, *func_args, **func_kwargs): with ctx as __ctx: func(*func_args, **func_kwargs, ctx=__ctx) but you can't do that itself as a lambda. And I consider modifying the ast cheating :P
                • masklinn 10y ago
                  > but you can't do that itself as a lambda. And I consider modifying the ast cheating :P No disagreement, really depends whether you're a "rules" or "spirit" kind of person though.
• masklinn 10y ago
  The latter can't really happen given Python is a statements- and indentations-based language. You'd need some really weird meta-magical syntax which really isn't going to happen in Python. Although you can cheat by fucking around with decorators e.g. def postfix(fn, *args): return lambda arg: fn(arg, *args) @postfix(map, range(5)) def result(i): return i * i print result # [0, 1, 4, 9, 16] (`postfix` is necessary because `map` takes its argument positionally so it's not possible to pass in the sequence with functools.partial)
  • dragonwriter 10y ago
    > The latter can't really happen given Python is a statements- and indentations-based language. Yeah, though I suppose you could hack around that and get nearly-full functionality in lambdas if you built a library that either wrapped non-expression statements in functions or provided equivalent functions. There are obviously some statements that there aren't good solutions for in that direction. OTOH, using named functions is in many cases more readable -- in the context of what is otherwise a normal Python codebase -- than the kind of lambdas that you can't easily write in Python. But I like the Coconut approach of but providing a more concise syntax for the kind of lambdas Python already supports.