Re: [ANN] Microlight (was Re: paving cowpaths with libraries)
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- Subject: Re: [ANN] Microlight (was Re: paving cowpaths with libraries)
- From: steve donovan <steve.j.donovan@...>
- Date: 2012年2月19日 11:54:59 +0200
On Sun, Feb 19, 2012 at 3:14 AM, Miles Bader <miles@gnu.org> wrote:
> "llib" and "lualib" are wayyyyyyyyyyyyyyyyyyyyyyyyyy too generic.
> I think only the real Lua team has the moral authority to get away with
> using names like that.
Very true; the name is not important, anyway.
If nothing else, tostring = ml.tstring gives a person a nicer
interactive experience with default table dumping.
I had some fun with 'mlx' where the X stands for
'Extension/Experiment/Evil'. The extension part is a List class
(although perhaps a better word is Array, since the adjective I
associate with 'List' is 'linked'). A common enough refrain is that
tables do not have a default metatable, so we're forced to spell out
table.sort, table.concat etc. List provides a suitable metatable for
table's array-like operations, plus the ml ones.
> import(_G,"mlx")
> words = List{'frodo','bilbo','sam'}
> = words:sub(2)
{"bilbo","sam"}
> words:sort()
> = words
{"bilbo","frodo","sam"}
> = words:concat ','
"bilbo,frodo,sam"
> = words:filter(string.match,'o$'):map(string.upper)
{"BILBO","FRODO"}
> l = List.range(10,50,10)
> = l:indexof(30)
3
> = l:indexby {1,3,5}
{10,30,50}
Personally I prefer method chaining (left-to-right) to functional
composition (right-to-left) with its implicit namespacing.
The experiment part is accessed with 'mlx.string_operators()' which
provides the standard binary operators like '+','*','[]' and some
synthetic ones like '{}' for table construction and '~' for
string.match.
> = l:map('+',1)
{11,21,31,41,51}
> = l:map2('+',{1,2})
{11,22}
The evil bit is giving all functions a metatable that provides
operators for functional expressions:
debug.setmetatable(print,{__concat=ml.compose,__mul=ml.bind1,__div=ml.bind2})
(Again, not automatic, have to say 'mlx.function_operators()')
> printf = io.write .. string.format
> ewrite = io.stderr.write*io.stderr
> zip = imap2 / '{}'
> = zip(l,{'one','two','three'},{1,2,3})
{{10,"one"},{20,"two"},{30,"three"}}
> isspace = string.match/'^s*$'
> = isspace '', isspace 'boo'
"" nil
Note how easy it is to build useful functions! My favourite is
triml = string.gsub/^%s+'/''
which is a very suggestive notation, at least for gsub.
However, at this point I realized I was mostly just entertaining
myself, and getting away from the Serious Business of defining a
little library ;)
Another candidate function which could be generally useful is sfilter,
which consumes and creates sequences generated by iterators.
for x,y in sfilter(io.lines(),string.match,'(%a+)=(.+)') do ... end
steve d.