Why not just use the Haskell approach? foo(x,y) = myfunc(bar) where: myfunc, bar = f(x), g(y) where: f,g = func1, func2 assuming func1 and func2 were previously defined, otherwise another "where" clause could follow. That way, introducing the "where" clause effectively causes foo to be defined as a function. Applying that to the previous example: l = [i for i in myiterator if fi] where: f = f(i) if "myiterator" was previously defined, or even: l = [i for i in myiterator if f(i)] where: myiterator, f = (i for i in xrange(10)), bool if "myiterator" was not previously defined. On Wed, Jul 15, 2009 at 8:49 AM, Daniel Stutzbach<daniel@stutzbachenterprises.com> wrote:
On Wed, Jul 15, 2009 at 2:55 AM, Greg Ewing <greg.ewing@canterbury.ac.nz> wrote:
One such extension might be a "where" block. Applied to the current problem:
foo(f) where: def f(x): ...
I like this proposal much more than any of the previous proposals. It has some of the flavor of Lisp's "let", but puts the important line first instead of at the end. In a nutshell, it says "define these symbols for this one line only". On the downside, for the common case of wanting to define a single function, the body of the function must be indented twice.
I suggest the following grammar and meaning, which would be referred to by the assignment, yield, return, and expression statements:
where_expression ::= expression_list "where" ":" suite | expression_list
It evaluates as follows.
[return|yield|x=] expression_list where: suite
is roughly equivalent to:
def where_expression(): suite return expression_list [return|yield|x=] expression_list()
How about the following as additional syntactic sugar for the common one-function case?
x = blah(f) where def f(item): body_of_f
-- Daniel Stutzbach, Ph.D. President, Stutzbach Enterprises, LLC
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