block lambda revival

Waldemar Horwat waldemar at google.com
Mon May 23 13:44:46 PDT 2011


This seems too brittle to me.  The examples conveniently include only lambda parameters in their function calls.  Suppose you have:

a = f{|| 42}

and want to add a second lambda parameter:

a = f{|| 42}{|x| x*x}

So far so good, ignoring the little bug that || is a different token than two |'s (we've yet to have a coherent discussion about what really can go into these parameter lists).

Now you want to add a third integer parameter:

a = f{|| 42}{|x| x*x}(7)

Well, that won't work, as it curries rather than supplying the third parameter.  Instead you'd need to do:

a = f({|| 42},{|x| x*x},7)

Oh, and don't forget to now insert the comma between the }{.  You'll get something entirely different (a lambda called with a lambda parameter, which it then ignores) if you omit it.


The other problem is the necessity of the [no line terminator here] imposed by semicolon insertion.  It's very tempting to write

a = f
   {|x| x*x}

which will at best be a syntax error or at worst be two separate statements (depending on whether we allow a lambda to start a statement).

     Waldemar


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