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//! Functional Libary for Rust //! //! This is still a work in progess.. //! //! Functor //! //! ``` //! use funlib::Functor; //! //! let s = Some(3).fmap(|&a| a * 2); // this will produce Some(6) //! //! ``` //! //! Monad //! //! ``` //! use funlib::Monad; //! //! let s = Some(3).bind(|&a| Some(a * 2)); // this will produce Some(6) //! //! ``` //! //! #![deny(missing_docs)] #[macro_use] pub mod macros; pub mod functor; pub mod applicative; pub mod monad; pub mod semigroup; pub mod monoid; pub mod foldable; use std::rc::Rc; /// Higher Kinded Type helper for M<A> -> M<B> pub trait HKT<B> { /// Current Type type A; /// Type M<B> type M; } /// Higher kinded Type helper for M<A> -> M<A> pub trait HKST<'a, B> { /// Current Type type A; /// Type M<A> type M; } derive_hkt!(Vec); derive_hkt!(Option); derive_hkt!(Box); derive_hkt!(Rc); /// Functor type class pub trait Functor<B>: HKT<B> { /// Functor map /// # Examples /// ``` /// use funlib::Functor; /// let n = Some(1).fmap(|i| i * 4); /// assert_eq!(Some(4), n); /// ``` fn fmap<F>(&self, f: F) -> Self::M where F: Fn(&Self::A) -> B; } /// Applicative type class pub trait Applicative<B>: Functor<B> { /// Lift values into the context of the Functor /// /// # Examples /// ``` /// use funlib::Applicative; /// let s1 = Option::<i8>::pure_(10); /// let s2 = Option::pure_("hi"); /// let v = Vec::pure_(1); /// ``` fn pure_(value: B) -> Self::M where Self: HKT<B, A=B>; /// Apply function is almost the same as Functor map. but the function isn't A => B but A<F => B> /// /// # Examples /// ``` /// use funlib::Applicative; /// fn double(i: &i32) -> i32 { i * 2 } /// let f: &dyn Fn(&i32) -> i32 = &|x| x * 2; /// assert_eq!(Some(4), Some(2).ap(Some(f))); /// assert_eq!(Some(4), Some(2).ap(Some(&double))); /// ``` fn ap<F>(&self, f: <Self as HKT<F>>::M) -> <Self as HKT<B>>::M where F: Fn(&<Self as HKT<B>>::A) -> B, Self:HKT<F>; } /// Monad type class pub trait Monad<B>: Applicative<B> { /// Bind works like map but it flattens nested structures /// /// # Examples /// ``` /// use funlib::Applicative; /// use funlib::Monad; /// fn over5(i: &i32) -> Option<i32> { if *i > 5 { Some(*i) } else { None }} /// let a = Some(4).bind(over5); /// let b = Some(6).bind(over5); /// assert_eq!(None, a); /// assert_eq!(Some(6), b); /// ``` fn bind<F>(&self, f: F) -> Self::M where F: Fn(&Self::A) -> Self::M; } /// Semigroup type class pub trait Semigroup: Clone { /// combine 2 of the same type /// /// # Examples /// /// ``` /// use funlib::Semigroup; /// assert_eq!(4i32, 1i32.mappend(&3i32)); /// assert_eq!(Some(4i32), Some(1i32).mappend(&Some(3i32))); /// ``` fn mappend(&self, other: &Self) -> Self; } /// Monoid type class extends the Semigroup and adds an empty function for the type pub trait Monoid: Semigroup { /// empty function same as Default /// /// # Examples /// /// ``` /// use funlib::{Monoid, Semigroup, Foldable::*}; /// let sum = vec![1i32,2i32,3i32,4i32].fold(i32::mempty(), |b,a| i32::mappend(&b, a)); /// assert_eq!(10i32, sum); /// assert_eq!(None::<i32>, Option::<i32>::mempty()); /// ``` fn mempty() -> Self; } /// Foldable mod containing the foldable type classes #[allow(non_snake_case)] pub mod Foldable { use crate::{HKST, HKT, Monoid}; /// FoladableA is for endo type functions pub trait FoldableA<'r, A: 'r>: HKST<'r, A> { /// Reduces the values of the Foldable into a single value /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// let sum = v.fold(0, |b, a| a + b); /// assert_eq!(10, sum); /// ``` fn fold<F>(&'r self, z: A, f: F) -> A where F: FnMut(A, &A) -> A; /// Using a Monoid reduce the values in the Foldable to a single value /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// let sum = v.concat(); /// assert_eq!(10, sum); /// ``` fn concat(&'r self) -> A where A: Monoid { self.fold(A::mempty(), |a,b| A::mappend(&a, b)) } /// Find a value in the foldable, returns an Option<&_> /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// let s = v.find(|&a| a == 2); /// let n = v.find(|&a| a == 5); /// assert_eq!(Some(&2), s); /// assert_eq!(None, n); /// ``` fn find<F>(&'r self, f: F) -> Option<&A> where F: Fn(&A) -> bool; /// Check if all values in the foldable returns true for function f /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// assert_eq!(true, v.all(|&a| a < 5)); /// assert_eq!(false, v.all(|&a| a < 4)); /// ``` fn all<F>(&'r self, f: F) -> bool where F: Fn(&A) -> bool; /// Check if any valu ein the foldable returns true for function f /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// assert_eq!(true, v.any(|&a| a == 4)); /// assert_eq!(false, v.any(|&a| a == 5)); /// ``` fn any<F>(&'r self, f: F) -> bool where F: Fn(&A) -> bool; /// Filters the foldable for values that meet the predicate /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// assert_eq!(vec![&1,&2], v.filter(|&a| a < 3)); /// ``` fn filter<F>(&'r self, f: F) -> Self::M where F: Fn(&A) -> bool; /// Checks if the foldable is empty /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// let v2: Vec<i32> = vec![]; /// assert_eq!(false, v.is_empty()); /// assert_eq!(true, v2.is_empty()); /// ``` fn is_empty(&'r self) -> bool; /// Checks if the foldable is non empty /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// let v = vec![1,2,3,4]; /// let v2: Vec<i32> = vec![]; /// assert_eq!(true, v.non_empty()); /// assert_eq!(false, v2.non_empty()); /// ``` fn non_empty(&'r self) -> bool { !self.is_empty() } } /// FoldableS is for Foldables that is not a list of some kind, ex. Option pub trait FoldableS<'r, A: 'r>: HKST<'r, A> { /// Reduces the values of the Foldable into a single value fn fold<F>(&'r self, z: A, f: F) -> A where F: Fn(&A) -> A; /// Find a value in the foldable, returns an Option<&_> fn find<F>(&'r self, f: F) -> Option<&A> where F: Fn(&A) -> bool; /// Check if all values in the foldable returns true for function f fn all<F>(&'r self, f: F) -> bool where F: Fn(&A) -> bool; /// Check if any valu ein the foldable returns true for function f fn any<F>(&'r self, f: F) -> bool where F: Fn(&A) -> bool; /// Filters the foldable for values that meet the predicate fn filter<F>(&'r self, f: F) -> Self::M where F: Fn(&A) -> bool; /// Checks if the foldable is empty fn is_empty(&'r self) -> bool; /// Checks if the foldable is non empty. fn non_empty(&'r self) -> bool { !self.is_empty() } } /// FoladableB is for Hinger Kinded Types where M<A> -> B / M<B> pub trait FoldableB<B>: HKT<B> { /// Reduces the values of the Foldable into a single value /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// #[derive(Debug, PartialEq)] /// struct Count(i32); /// let v = vec![1,2,3,4]; /// let sum = v.fold_right(Count(0), |a, b| Count(a + b.0)); /// assert_eq!(Count(10), sum); /// ``` fn fold_right<F>(&self, z: B, f: F) -> B where F: Fn(&Self::A, B) -> B; /// Reduces the values of the Foldable into a single value /// /// # Examples /// /// ``` /// use funlib::Foldable::*; /// #[derive(Debug, PartialEq)] /// struct Count(i32); /// let v = vec![1,2,3,4]; /// let sum: Count = v.fold_left(Count(0), |b, a| Count(a + b.0)); /// assert_eq!(Count(10), sum); /// ``` fn fold_left<F>(&self, z: B, f: F) -> B where F: Fn(B, &Self::A) -> B; /// Using a Monoid and a function to transform the Foldable values form A -> b to reduce the values in the Foldable to a single value of B fn fold_map<F>(&self, f: F) -> B where F: Fn(&Self::A) -> B, B: Monoid { self.fold_left(B::mempty(), |b, a| B::mappend(&b, &f(&a))) } } }