abuse of lambda question

[Michael Hudson]

Before we start: you're a sick man.

Ben Wolfson <rumjuggler at cryptarchy.org> writes:

> I'm attempting to abuse Python's lambdas, and I've come across a
> problem I can't figure out.  Well, the problem is actually that I'm
> attempting to abuse lambdas, but aside from that I don't know why the
> abuse is failing.  Here's what I've got:
> 
> def __everyother(): #factory to return lambdas.
> 	return lambda l, evens, odds, app=lambda a,e: lambda
> a=a,e=e:a.append(e): Compose(apply(map, (lambda e, evens=evens,
> odds=odds, l=l,app=app: If(l.index(e)%2==0, app(evens,e), app(odds,e))
> ,l)), Return(evens, odds))
> 
> The functions it calls are:
> 
> def Return(*args):
> 	return lambda args=args: args
> 
> def Compose(*args):
> 	return lambda fs=args: For(len(fs), lambda c, fs=fs:
> If(lambda c=c,fs=fs: c==len(fs)-1, Return(fs[-1]()), fs[c]))()
> 
> def For(count, fct, *args, **kwargs):
> 	for i in range(count):
> 		fct(i,*args,**kwargs)

You don't post the code for If, and I'm a bit confused, because in one
place:

> odds=odds, l=l,app=app: If(l.index(e)%2==0, app(evens,e), app(odds,e))

you pass a value as the first parameter, and in another:

> If(lambda c=c,fs=fs: c==len(fs)-1, Return(fs[-1]()), fs[c]))()

you pass a thunk.  Which do you want?  I suspect this may be giving
the error you're suffering, though I can't get it to work at all.

Also:

> a=a,e=e:a.append(e): Compose(apply(map, (lambda e, evens=evens,
                               ^^^^^
what's this apply for?

i'm-sure-this-is-good-practice-for-a-maths-exam-ly y'rs
Michael

-- 
  I also fondly recall Paris because that's where I learned to
  debug Zetalisp while drunk.                          -- Olin Shivers