Difference between revisions of "Functional C++"
Line 1: | Line 1: | ||
+ | C++ is a multiparadigm, many level of abstracions, and very little overhead - runtime cost. | ||
+ | |||
+ | Usually procedural, object-oriented, but functional style is also possible. Not strictly functional, but possible to use problem solving schemas and basic bulding blocks (working with values as opposed to identities) | ||
+ | |||
+ | C++ 11 standard expands this support with lambdas | ||
+ | |||
+ | |||
+ | immutable data structures that maintains the speed C++ is known for while providing the protection that functional languages | ||
+ | |||
+ | |||
Revision as of 12:58, 12 January 2015
C++ is a multiparadigm, many level of abstracions, and very little overhead - runtime cost.
Usually procedural, object-oriented, but functional style is also possible. Not strictly functional, but possible to use problem solving schemas and basic bulding blocks (working with values as opposed to identities)
C++ 11 standard expands this support with lambdas
immutable data structures that maintains the speed C++ is known for while providing the protection that functional languages
Function Equivalence | |
---|---|
Haskell | C++ |
map | for_each |
foldl | accumulate |
foldr | accumulate |
filter | copy_if |
replicate | fill_n |
Contents
map
template<class InputIterator, class Function>
Function for_each(InputIterator first, InputIterator last, Function fn)
{
while (first!=last) {
fn (*first);
++first;
}
return move(fn);
}
template <class InputIterator, class OutputIterator, class UnaryOperator>
OutputIterator transform (InputIterator first1, InputIterator last1,
OutputIterator result, UnaryOperator op)
{
while (first1 != last1) {
*result = op(*first1); // or: *result=binary_op(*first1,*first2++);
++result; ++first1;
}
return result;
}
foldl
template <class InputIterator, class T>
T accumulate (InputIterator first, InputIterator last, T init)
{
while (first!=last) {
init = init + *first; // or: init=binary_op(init,*first) for the binary_op version
++first;
}
return init;
}
foldr
user rbegin and rend
template <class InputIterator, class T>
T accumulate (InputIterator first, InputIterator last, T init)
{
while (first!=last) {
init = init + *first; // or: init=binary_op(init,*first) for the binary_op version
++first;
}
return init;
}
filter
template <class InputIterator, class OutputIterator, class UnaryPredicate>
OutputIterator copy_if (InputIterator first, InputIterator last,
OutputIterator result, UnaryPredicate pred)
{
while (first!=last) {
if (pred(*first)) {
*result = *first;
++result;
}
++first;
}
return result;
}
replicate
template <class OutputIterator, class Size, class T>
OutputIterator fill_n (OutputIterator first, Size n, const T& val)
{
while (n>0) {
*first = val;
++first; --n;
}
return first;
}
template <class ForwardIterator, class T>
void fill (ForwardIterator first, ForwardIterator last, const T& val)
{
while (first != last) {
*first = val;
++first;
}
}