Would Anonymous Functions Help in Learning Programming/Python?

Bryan Olson fakeaddress at nowhere.org
Sat Sep 22 21:12:31 CEST 2007


Cristian wrote:
> [...] Specifically, he's having trouble
> thinking of functions as first order data (don't worry, I haven't
> confused him with such terminology yet). 
[...]
> And, after we finally
> get a hold of first order functions, we appreciate its incorporation
> into languages. It would be a shame if my friend just learns the
> motions and never incorporates first order functions into his
> programs. 


The terminology I've heard for this is that functions are
"first-class values". There's a minor name-collision on
"class", but people have heard "first-class" in other
contexts, and it means the same thing here: no second-class
status for such values.

"First order" has other usages, some contradicting what you
mean. First-order functions are exactly those that cannot
take functions as arguments. It would be a shame if your
friend never incorporates *higher order* functions.
[http://en.wikipedia.org/wiki/Higher-order_function]


[...]
> my_function = function(foo, bar): pass
> an_instance_method = function(self, foo): pass
> a_method_declaration = method(self, foo): pass

I just argued for adopting mainstream terminology, but here
I like yours better. The keyword "lambda" sucks. All the
other keywords, having been so carefully chosen to relate
to their conversational usage, have mis-trained to look
at this spelling-out of the name of an arbitrary symbol.

Alonzo Church's calculus used the *symbol*. He just needed
it to be distinct. Could as well have been the '$-calculus'.

Function-as-value is not a trivial concept. I remember
wrestling with it, and I've seen many others do the same.
The 'lambda' keyword is so awful as to pass for deep
mystery long after students have grasped first-class
functions.


"function" would be a much better keyword. Or follow ML and
abbreviate to "fn", or choose another term that clues one
in to the meaning. I'd have caught on much quicker given a
a hint to read:

    lambda x, y: x + y

as: "the function of two variables, call them x and y, that
returns x + y."


--Bryan



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