LeechCraft  0.6.70-6645-gcd10d7e
Modular cross-platform feature rich live environment.
monadplus.h
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29 
30 #pragma once
31 
32 #include <boost/optional.hpp>
33 
34 namespace LeechCraft
35 {
36 namespace Util
37 {
38  template<typename T>
40 
41  template<typename MP>
42  MP Mzero ()
43  {
45  }
46 
47  const struct
48  {
49  template<typename MP>
50  auto operator() (const MP& m1) const
51  {
52  return [m1] (const MP& m2) { return InstanceMonadPlus<MP>::Mplus (m1, m2); };
53  }
54  } Mplus {};
55 
56  template<typename MP>
57  auto operator+ (const MP& m1, const MP& m2) -> decltype (Mplus (m1) (m2))
58  {
59  return Mplus (m1) (m2);
60  }
61 
62  template<typename T>
63  struct InstanceMonadPlus<boost::optional<T>>
64  {
65  static boost::optional<T> Mzero ()
66  {
67  return {};
68  }
69 
70  static boost::optional<T> Mplus (const boost::optional<T>& t1, const boost::optional<T>& t2)
71  {
72  return t1 ? t1 : t2;
73  }
74  };
75 }
76 }
static boost::optional< T > Mplus(const boost::optional< T > &t1, const boost::optional< T > &t2)
Definition: monadplus.h:70
auto operator+(const MP &m1, const MP &m2) -> decltype(Mplus(m1)(m2))
Definition: monadplus.h:57
const struct LeechCraft::Util::@1 Mplus