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comp.lang.lisp

Re: Multivalue tail recursion?

William James

12/28/2015 5:39:00 PM

> > Loops like:
> >
> > (loop for x below 10 collect x)
>
> range(10)


MatzLisp (Ruby):

(0..9).to_a
==>[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>
> >
> > (loop for x in '(3 5 7)
> > for y in '(2 5 8)
> > when (= x y)
> > collect (cons x y))
> >
>
> [(x, y) for x, y in zip([3,5,7], [2,5,8])
> if x == y]


[0,4,6,7].zip([2,4,5,7]).select{|a,b| a==b}
==>[[4, 4], [7, 7]]


>
> > (defun lookup (key table)
> > (loop for (ind val) in table
> > when (eq key ind)
> > return val))
>
> def lookup (key, table):
> for ind, val in table.iteritems():
> if key == ind: return val

def lookup key, table
(table.find{|k,v| k==key} || []).last
end

lookup :b, [[:a,2],[:b,3]]
==>3
lookup :xxx, [[:a,2],[:b,3]]
==>nil

Another way:

def lookup key, table
table.each{|k,v| return v if k==key}
nil
end

lookup :b, [[:a,2],[:b,3]]
==>3
lookup :xxx, [[:a,2],[:b,3]]
==>nil


Another way:

def lookup key, table
(table.assoc(key) || []).last
end

lookup :b, [[:a,2],[:b,3]]
==>3
lookup :xxx, [[:a,2],[:b,3]]
==>nil


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