Re: iterator sequences (was: Standard libraries)
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- Subject: Re: iterator sequences (was: Standard libraries)
- From: Mark Hamburg <mark@...>
- Date: Fri, 1 Jan 2010 13:13:34 -0800
The following modification results in more efficient iteration (by stripping out the test) at the expense of having to add an explicit terminator to the sequence. I believe I've preserved the full seq semantics.
function iterate(seq)
return seq -- not really meant to be called, but we'll make it safe
end
function seq(f, state, key)
local function self(s, k, ...)
if type(s) == "function" then
if s == iterate then
return f, state, key
end
f = s(self, f, k, ...) or f
return self, state, key
else
return f(s, k)
end
end
return self, state, key
end
-- Other material elided...
for i, x in seq(ipairs(list)) (map, square) (filter, is_odd) (iterate) do
print(i, x)
end