Hi! Someone alerted me to this, so I had to sign up.

Here's my mostly-iterative one line brainfuck interpreter I wrote a few months ago. It gets around the import line by using inline imports (__import__) and around the while issue using itertools.repeat(). Since it uses no recursion, stack space is not a problem =).

(lambda t:(lambda a:(lambda b:(lambda l,e,s:((lambda(Y,o,N,A,t),a,n:e('v',(Y,o,N,A,t))or[e('v',(lambda(Y,o,N,A,t):(/>{'>':(lambda(Y,o,N,A,t),a,n:(Y,o,N+1,A+1,t)),'<':(lambda(Y,o,N,A,t),a,n:(Y,o,N-1,A+1,t)),'+':(lambda(Y,o,N,A,t),a,n:((Y[:N]+[Y[N]+1]+Y[N+1:],o,N,A+1,t)if N>=0 else(Y,o[:-N-1]+[o[-N-1]+1]+o[-N:],N,A+1,t))),'-':(lambda(Y,o,N,A,t),a,n:((Y[:N]+[Y[N]-1]+Y[N+1:],o,N,A+1,t)if N>=0 else(Y,o[:-N-1]+[o[-N-1]-1]+o[-N:],N,A+1,t))),'.':(lambda(Y,o,N,A,t),a,n:__import__('sys').stdout.write(chr(Y[N] if N>=0 else o[-N-1]))or(Y,o,N,A+1,t)),',':(lambda(Y,o,N,A,t),a,n:(Y[:N]+[ord(t[0])if len(t)else -1]+Y[N+1:]if A>=0 else Y,o[:-N-1]+[ord(t[0])if len(t)else -1]+o[-N:]if A<0 else o,N,A+1,t[1:])),'[':(lambda(Y,o,N,A,t),a,n:(Y,o,N,n[A]+1 if(Y[N]==0 if N>=0 else o[-N-1]==0)else A+1,t)),']':(lambda(Y,o,N,A,t),a,n:(Y,o,N,n[A]+1 if(Y[N]>=1 if N>=0 else o[-N-1]>=1)else A+1,t))}[a[A]]((Y+[0]*(9+len(Y)) if A>=len(Y)-5 else Y,o+[0]*(9+len(o)) if -A>=len(o)-5 else o,N,A,t),a,n)if A<len(a)else False))(l('v')))for i in s.takewhile(lambda x:l('v')!=False,s.count())])(([],[],0,0,t),a,dict(e('g',[])or e('l',[])or[e('l',l('l')+[i])if a[i]=='['else(e('g',l('g')+[(l('l')[-1],i),(i,l('l')[-1])])or e('l',l('l')[:-1]))for i in range(len(a))if a[i] in'[]'][:0]or l('g'))))[:0])(b.__getattribute__,b.__setattr__,__import__('itertools')))(lambda:a)or None)(filter("<.+[,->]".count,open(__import__('sys').argv[1]).read())))(raw_input()) 

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