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Power set: Difference between revisions
added FunL
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a.subsets[]
</lang>
=={{header|FunL}}==
FunL uses Scala type <code>scala.collection.immutable.Set</code> as it's set type, which has a built-in method <code>subsets</code> returning an (Scala) iterator over subsets.
<lang funl>def powerset( s ) = s.subsets().toSet()</lang>
The powerset function could be implemented in FunL directly as:
<lang funl>def
powerset( {} ) = {{}}
powerset( s ) =
acc = powerset( s.tail() )
acc + map( x -> {s.head()} + x, acc )</lang>
or, alternatively as:
<lang funl>import lists.foldr
def powerset( s ) = foldr( (x, acc) -> acc + map( a -> {x} + a, acc), {{}}, s )
println( powerset({1, 2, 3, 4}) )</lang>
{{out}}
<pre>
{{}, {4}, {1, 2}, {1, 3}, {2, 3, 4}, {3}, {1, 2, 3, 4}, {1, 4}, {1, 2, 3}, {2}, {1, 2, 4}, {1}, {3, 4}, {2, 3}, {2, 4}, {1, 3, 4}}
</pre>
=={{header|GAP}}==
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