3 ms·

That's one of the problems: Inline blocks are fundamentally incompatible with significant whitespace, or at least no one has thought of a good way to combine th

• nathanic 17y ago
  I personally like how Haskell can combine the two. You can have: myFunc = do this that other Or equivalently: myFunc = do { this; that; other; }
  • natrius 17y ago
    How does the first form work out as an inline function argument? I'm not familiar with Haskell's syntax.
    • nathanic 17y ago
      I think I misunderstood you before. I thought you were talking about putting multiple statements on a line. But Haskell can pass around code blocks as well, with or without significant whitespace. For example, I can define a function called 'forever' to run a sequence of actions forever like so: forever x = x >> forever x Where 'x' is any sequence of actions. You can pronounce '>>' as "followed by". (These are monadic actions, actually, but nevermind that.) I can invoke it like so: myFunc = forever (do {this; that; other}) or: myFunc = forever $ do this that other The dollar sign is a function that lets you dispense with some parentheses. Think of it like an opening paren that closes at the end of the subexpression it's in. If the block is a function rather than a sequence of actions, Haskell uses '\' as a lambda for introducing anonymous functions. For example, the function 'map' takes a unary function and calls it with each value from a list. Below I'll call it with an anonymous function which returns double its argument: map (\x -> x * 2) [1,2,3] This results in a new list [2,4,6].
      • shrughes 17y ago
        Another good example: forM_ [1..9] $ \i -> do this i that other
• jules 17y ago
  Easy. The rule is that every time you see : like this: bla bla foo: x y z It's the same as this: bla bla foo x y end z i.e. insert `end` when the indentation ends.
  • natrius 17y ago
    How about when the function is being passed as an argument to a function? Does the ')' just go on the next line by itself? What if it's not the last argument? There are many opportunities for ambiguity and/or ugliness.
    • grandalf 17y ago
      in Python, it works like: foo(a, b, lambda x: x+2) or foo2(a, b, foo): foo() # this is like js The lambda is closed by the next ) or ,
      • natrius 17y ago
        Right, but you can't have multi-line anonymous functions, which are pleasant to use in Ruby and JavaScript.
        • grandalf 17y ago
          True, but you can just write a non-anyonymous function in the current scope, which can be passed as boo or called as boo(): def test(): def boo(x): x += 2 x += 3 return x something_else(boo, 33, "hi") test() This is equivalent to how procs are often used in Ruby...
    • jules 17y ago
      collection.each(lambda x: ... ... ) Or if the language doesn't require () to call a method, and uses `do` instead of `lambda`: collection.each do x: ... ... If it's not the first argument: map(lambda x: ... ... , collection) Yes this is ugly, but using a multi line anonymous function in the middle of an argument list will always be ugly.