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generic tests + CopyFunctor

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AF 2023-03-10 23:00:10 +00:00
parent 0b0914bd4e
commit 85df7b2092
4 changed files with 506 additions and 296 deletions
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141
src/copy_func.rs Normal file
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@ -0,0 +1,141 @@
use super::func::*;
pub trait CopyWeakFunctor {
type CF<A: Copy>;
}
pub trait CopyFunctor: CopyWeakFunctor {
fn copy_fmap<A: Copy, B: Copy, F: Fn(A) -> B>(f: F, fa: Self::CF<A>) -> Self::CF<B>;
fn copy_replace<A: Copy, B: Copy>(fa: Self::CF<A>, b: B) -> Self::CF<B> {
Self::copy_fmap(|_| b, fa)
}
fn copy_void<A: Copy>(fa: Self::CF<A>) -> Self::CF<()> {
Self::copy_replace(fa, ())
}
}
impl<T: WeakFunctor> CopyWeakFunctor for T {
type CF<A: Copy> = T::F<A>;
}
impl<T: Functor> CopyFunctor for T {
fn copy_fmap<A: Copy, B: Copy, F: Fn(A) -> B>(f: F, fa: Self::CF<A>) -> Self::CF<B> {
Self::fmap(f, fa)
}
fn copy_replace<A: Copy, B: Copy>(fa: Self::CF<A>, b: B) -> Self::CF<B> {
Self::replace(fa, b)
}
fn copy_void<A: Copy>(fa: Self::CF<A>) -> Self::CF<()> {
Self::void(fa)
}
}
pub trait CopyApplicativeSeq: CopyFunctor {
fn copy_seq<A: Copy, B: Copy, F: Copy + Fn(A) -> B>(
ff: Self::CF<F>,
fa: Self::CF<A>,
) -> Self::CF<B>;
fn _copy_la2<A: Copy, B: Copy, C: Copy, F: Copy + Fn(A, B) -> C>(
f: F,
fa: Self::CF<A>,
fb: Self::CF<B>,
) -> Self::CF<C> {
Self::copy_seq(Self::copy_fmap(|a| move |b| f(a, b), fa), fb)
}
}
impl<T: ApplicativeSeq> CopyApplicativeSeq for T {
fn copy_seq<A: Copy, B: Copy, F: Copy + Fn(A) -> B>(
ff: Self::CF<F>,
fa: Self::CF<A>,
) -> Self::CF<B> {
Self::seq(ff, fa)
}
}
pub trait CopyApplicativeLA2: CopyFunctor {
fn copy_la2<A: Copy, B: Copy, C: Copy, F: Fn(A, B) -> C>(
f: F,
fa: Self::CF<A>,
fb: Self::CF<B>,
) -> Self::CF<C>;
fn _copy_seq<A: Copy, B: Copy, F: Copy + Fn(A) -> B>(
ff: Self::CF<F>,
fa: Self::CF<A>,
) -> Self::CF<B> {
Self::copy_la2(|f, a| f(a), ff, fa)
}
}
impl<T: ApplicativeLA2> CopyApplicativeLA2 for T {
fn copy_la2<A: Copy, B: Copy, C: Copy, F: Fn(A, B) -> C>(
f: F,
fa: Self::CF<A>,
fb: Self::CF<B>,
) -> Self::CF<C> {
Self::la2(f, fa, fb)
}
}
pub trait CopyApplicative: CopyFunctor + CopyApplicativeSeq + CopyApplicativeLA2 {
fn copy_pure<A: Copy>(a: A) -> Self::CF<A>;
fn copy_discard_first<A: Copy, B: Copy>(fa: Self::CF<A>, fb: Self::CF<B>) -> Self::CF<B> {
Self::copy_seq(Self::copy_replace(fa, |b| b), fb)
}
fn copy_discard_second<A: Copy, B: Copy>(fa: Self::CF<A>, fb: Self::CF<B>) -> Self::CF<A> {
Self::copy_la2(|a, _| a, fa, fb)
}
}
impl<T: Applicative> CopyApplicative for T {
fn copy_pure<A: Copy>(a: A) -> Self::CF<A> {
Self::pure(a)
}
fn copy_discard_first<A: Copy, B: Copy>(fa: Self::CF<A>, fb: Self::CF<B>) -> Self::CF<B> {
Self::discard_first(fa, fb)
}
fn copy_discard_second<A: Copy, B: Copy>(fa: Self::CF<A>, fb: Self::CF<B>) -> Self::CF<A> {
Self::discard_second(fa, fb)
}
}
pub trait CopyMonad: CopyApplicative {
fn copy_bind<A: Copy, B: Copy, F: FnOnce(A) -> Self::CF<B>>(
fa: Self::CF<A>,
f: F,
) -> Self::CF<B>;
fn copy_join<A: Copy>(ffa: Self::CF<Self::CF<A>>) -> Self::CF<A>
where
Self::CF<A>: Copy,
{
// ugly
Self::copy_bind(ffa, |fa| fa)
}
}
impl<T: Monad> CopyMonad for T {
fn copy_bind<A: Copy, B: Copy, F: FnOnce(A) -> Self::CF<B>>(
fa: Self::CF<A>,
f: F,
) -> Self::CF<B> {
T::bind(fa, f)
}
fn copy_join<A: Copy>(ffa: Self::CF<Self::CF<A>>) -> Self::CF<A>
where
Self::CF<A>: Copy,
{
T::join(ffa)
}
}

542
src/func.rs
View File

@ -1,6 +1,8 @@
pub trait Functor {
type F<T>;
pub trait WeakFunctor {
type F<A>;
}
pub trait Functor: WeakFunctor {
fn fmap<A, B, F: FnOnce(A) -> B>(f: F, fa: Self::F<A>) -> Self::F<B>;
fn replace<A, B>(fa: Self::F<A>, b: B) -> Self::F<B> {
@ -14,28 +16,18 @@ pub trait Functor {
pub trait ApplicativeSeq: Functor {
fn seq<A, B, F: FnOnce(A) -> B>(ff: Self::F<F>, fa: Self::F<A>) -> Self::F<B>;
fn _la2<A, B, C, F: FnOnce(A, B) -> C>(f: F, fa: Self::F<A>, fb: Self::F<B>) -> Self::F<C> {
Self::seq(Self::fmap(|a| |b| f(a, b), fa), fb)
}
}
pub trait ApplicativeLA2: Functor {
fn la2<A, B, C, F: FnOnce(A, B) -> C>(f: F, fa: Self::F<A>, fb: Self::F<B>) -> Self::F<C>;
}
pub trait ApplicativeSeqOnly: ApplicativeSeq {}
pub trait ApplicativeLA2Only: ApplicativeLA2 {}
impl<T: ApplicativeLA2Only> ApplicativeSeq for T {
fn seq<A, B, F: FnOnce(A) -> B>(ff: Self::F<F>, fa: Self::F<A>) -> Self::F<B> {
fn _seq<A, B, F: FnOnce(A) -> B>(ff: Self::F<F>, fa: Self::F<A>) -> Self::F<B> {
Self::la2(|f, a| f(a), ff, fa)
}
}
impl<T: ApplicativeSeqOnly> ApplicativeLA2 for T {
fn la2<A, B, C, F: FnOnce(A, B) -> C>(f: F, fa: Self::F<A>, fb: Self::F<B>) -> Self::F<C> {
Self::seq(Self::fmap(|a| |b| f(a, b), fa), fb)
}
}
pub trait Applicative: Functor + ApplicativeSeq + ApplicativeLA2 {
fn pure<A>(a: A) -> Self::F<A>;
@ -56,80 +48,75 @@ pub trait Monad: Applicative {
}
}
pub struct OptionClass;
impl Functor for OptionClass {
type F<T> = Option<T>;
fn fmap<A, B, F: FnOnce(A) -> B>(f: F, fa: Self::F<A>) -> Self::F<B> {
match fa {
Some(a) => Some(f(a)),
None => None,
}
}
fn replace<A, B>(fa: Self::F<A>, b: B) -> Self::F<B> {
match fa {
Some(_) => Some(b),
None => None,
}
}
}
impl ApplicativeSeq for OptionClass {
fn seq<A, B, F: FnOnce(A) -> B>(ff: Self::F<F>, fa: Self::F<A>) -> Self::F<B> {
match (ff, fa) {
(Some(f), Some(a)) => Some(f(a)),
_ => None,
}
}
}
impl ApplicativeLA2 for OptionClass {
fn la2<A, B, C, F: FnOnce(A, B) -> C>(f: F, fa: Self::F<A>, fb: Self::F<B>) -> Self::F<C> {
match (fa, fb) {
(Some(a), Some(b)) => Some(f(a, b)),
_ => None,
}
}
}
impl Applicative for OptionClass {
fn pure<A>(a: A) -> Self::F<A> {
Some(a)
}
fn discard_first<A, B>(fa: Self::F<A>, fb: Self::F<B>) -> Self::F<B> {
match fa {
Some(_) => fb,
None => None,
}
}
}
impl Monad for OptionClass {
fn bind<A, B, F: FnOnce(A) -> Self::F<B>>(fa: Self::F<A>, f: F) -> Self::F<B> {
match fa {
Some(a) => f(a),
None => None,
}
}
}
#[cfg(test)]
mod tests {
pub mod tests {
use super::*;
use core::fmt::Debug;
use std::ops::{Add, AddAssign};
pub fn make_none<T>(_: Option<T>) -> Option<T> {
None
pub struct TestResults(usize, usize, Result<(), String>);
pub type R = TestResults;
impl R {
pub fn unwrap(self) {
match self {
TestResults(success, total, Err(e)) => panic!("failed:\n{success}/{total}\n{e}\n"),
_ => (),
};
}
}
pub fn fmap_respects_identity<T: Functor, A, FA0: Fn() -> T::F<A>>(fa0: FA0)
fn eqr<T: PartialEq + Debug>(name: &str, left: T, right: T) -> R {
if left == right {
TestResults(1, 1, Ok(()))
} else {
TestResults(0, 1, Err(format!("{name}: {:?} != {:?}", left, right)))
}
}
impl Default for R {
fn default() -> Self {
Self(0, 0, Ok(()))
}
}
impl Add for R {
type Output = R;
fn add(self, rhs: Self) -> Self::Output {
Self(
self.0 + rhs.0,
self.1 + rhs.1,
match (self.2, rhs.2) {
(Err(le), Err(re)) => Err(le + "\n" + re.as_str()),
(e, Ok(_)) => e,
(Ok(_), e) => e,
},
)
}
}
impl AddAssign<R> for R {
fn add_assign(&mut self, rhs: R) {
self.0 += rhs.0;
self.1 += rhs.1;
match (&mut self.2, rhs.2) {
(Err(ref mut le), Err(re)) => {
*le += "\n";
*le += re.as_str()
}
(_, Ok(_)) => {}
(lr, Err(re)) => *lr = Err(re),
}
}
}
pub fn fmap_respects_identity<T: Functor, A, FA0: Fn() -> T::F<A>>(fa0: FA0) -> R
where
T::F<A>: Debug + PartialEq,
{
assert_eq!(T::fmap(|a| a, fa0()), fa0());
eqr("identity: fmap id == id", T::fmap(|a| a, fa0()), fa0())
}
pub fn fmap_respects_composition<
@ -144,17 +131,26 @@ mod tests {
f: F,
g: G,
fa0: FA0,
) where
) -> R
where
T::F<C>: Debug + PartialEq,
{
assert_eq!(T::fmap(|a| f(g(a)), fa0()), T::fmap(f, T::fmap(g, fa0())));
eqr(
"composition: fmap (f . g) == fmap f . fmap g",
T::fmap(|a| f(g(a)), fa0()),
T::fmap(f, T::fmap(g, fa0())),
)
}
pub fn seq_respects_identity<T: Applicative, A, FA0: Fn() -> T::F<A>>(fa0: FA0)
pub fn seq_respects_identity<T: Applicative, A, FA0: Fn() -> T::F<A>>(fa0: FA0) -> R
where
T::F<A>: Debug + PartialEq,
{
assert_eq!(T::seq(T::pure(|a| a), fa0()), fa0());
eqr(
"identity: pure id <*> v = v",
T::seq(T::pure(|a| a), fa0()),
fa0(),
)
}
pub fn seq_respects_composition<
@ -171,28 +167,35 @@ mod tests {
ff0: FF0,
fg0: FG0,
fa0: FA0,
) where
) -> R
where
T::F<C>: Debug + PartialEq,
{
assert_eq!(
eqr(
"composition: pure (.) <*> u <*> v <*> w = u <*> (v <*> w)",
T::seq(
T::seq(
T::seq(T::pure(|f: F| |g: G| move |a| f(g(a))), ff0()),
fg0()
fg0(),
),
fa0()
fa0(),
),
T::seq(ff0(), T::seq(fg0(), fa0()))
);
T::seq(ff0(), T::seq(fg0(), fa0())),
)
}
pub fn seq_is_homomorphic<T: Applicative, A, B, A0: Fn() -> A, F: Copy + Fn(A) -> B>(
f: F,
a0: A0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(T::seq(T::pure(f), T::pure(a0())), T::pure(f(a0())));
eqr(
"homomorphism: pure f <*> pure x = pure (f x)",
T::seq(T::pure(f), T::pure(a0())),
T::pure(f(a0())),
)
}
pub fn seq_respects_interchange<
@ -205,13 +208,15 @@ mod tests {
>(
ff0: FF0,
a0: A0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(
eqr(
"interchange: u <*> pure y = pure ($ y) <*> u",
T::seq(ff0(), T::pure(a0())),
T::seq(T::pure(|f: F| f(a0())), ff0())
);
T::seq(T::pure(|f: F| f(a0())), ff0()),
)
}
pub fn seq_can_be_expressed_via_la2<
@ -224,10 +229,15 @@ mod tests {
>(
ff0: FF0,
fa0: FA0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(T::seq(ff0(), fa0()), T::la2(|f, a| f(a), ff0(), fa0()));
eqr(
"seq via la2: (<*>) = liftA2 id",
T::seq(ff0(), fa0()),
T::la2(|f, a| f(a), ff0(), fa0()),
)
}
pub fn fmap_can_be_expressed_via_seq<
@ -239,10 +249,15 @@ mod tests {
>(
f: F,
fa0: FA0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(T::fmap(f, fa0()), T::seq(T::pure(f), fa0()));
eqr(
"fmap via seq: fmap f x = pure f <*> x",
T::fmap(f, fa0()),
T::seq(T::pure(f), fa0()),
)
}
pub fn discard_can_be_expressed_via_seq_or_la2<
@ -254,33 +269,44 @@ mod tests {
>(
fa0: FA0,
fb0: FB0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(
eqr(
"discard via seq: u *> v = (id <$ u) <*> v",
T::discard_first(fa0(), fb0()),
T::seq(T::replace(fa0(), |b| b), fb0())
);
assert_eq!(
T::seq(T::replace(fa0(), |b| b), fb0()),
) + eqr(
"discard via la2: u <* v = liftA2 const u v",
T::discard_second(fb0(), fa0()),
T::la2(|b, _| b, fb0(), fa0())
);
T::la2(|b, _| b, fb0(), fa0()),
)
}
pub fn bind_respects_left_identity<T: Monad, A, B, F: Copy + Fn(A) -> T::F<B>, A0: Fn() -> A>(
f: F,
a0: A0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(T::bind(T::pure(a0()), f), f(a0()));
eqr(
"left identity: pure a >>= k = k a",
T::bind(T::pure(a0()), f),
f(a0()),
)
}
pub fn bind_respects_right_identity<T: Monad, A, FA0: Fn() -> T::F<A>>(fa0: FA0)
pub fn bind_respects_right_identity<T: Monad, A, FA0: Fn() -> T::F<A>>(fa0: FA0) -> R
where
T::F<A>: Debug + PartialEq,
{
assert_eq!(T::bind(fa0(), T::pure), fa0());
eqr(
"right identity: m >>= bind = m",
T::bind(fa0(), T::pure),
fa0(),
)
}
pub fn bind_is_associative<
@ -295,13 +321,15 @@ mod tests {
f: F,
g: G,
fa0: FA0,
) where
) -> R
where
T::F<C>: Debug + PartialEq,
{
assert_eq!(
eqr(
r"associativity: m >>= (\x -> k x >>= h) = (m >>= k) >>= h",
T::bind(fa0(), |a| T::bind(g(a), f)),
T::bind(T::bind(fa0(), g), f)
);
T::bind(T::bind(fa0(), g), f),
)
}
pub fn seq_can_be_expressed_via_bind<
@ -314,13 +342,15 @@ mod tests {
>(
ff0: FF0,
fa0: FA0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(
eqr(
r"seq via bind: m1 <*> m2 = m1 >>= (\x1 -> m2 >>= (\x2 -> pure (x1 x2)))",
T::seq(ff0(), fa0()),
T::bind(ff0(), |f| T::bind(fa0(), |a| T::pure(f(a))))
);
T::bind(ff0(), |f| T::bind(fa0(), |a| T::pure(f(a)))),
)
}
pub fn fmap_can_be_expressed_via_bind<
@ -332,195 +362,115 @@ mod tests {
>(
f: F,
fa0: FA0,
) where
) -> R
where
T::F<B>: Debug + PartialEq,
{
assert_eq!(T::fmap(f, fa0()), T::bind(fa0(), |a| T::pure(f(a))));
eqr(
"fmap via bind: fmap f xs = xs >>= return . f",
T::fmap(f, fa0()),
T::bind(fa0(), |a| T::pure(f(a))),
)
}
}
#[cfg(test)]
mod option_tests {
use crate::func::tests;
pub mod test_suite {
use std::fmt::Debug;
use super::{tests::make_none, Functor, OptionClass as T};
use super::tests::*;
use super::*;
#[test]
fn fmap_f_none_is_none() {
assert_eq!(T::fmap(|_: ()| (), None), None);
pub trait FunctorTestSuite: WeakFunctor {
fn sample<A>() -> Vec<Box<dyn Fn(A) -> Self::F<A>>>;
}
#[test]
fn fmap_f_some_a_is_some_f_a() {
assert_eq!(T::fmap(|x| x * x, Some(2)), Some(4));
pub fn functor_follows_laws<T: Functor + FunctorTestSuite>() -> R
where
T::F<i32>: Debug + PartialEq,
{
let mut res = R::default();
for pa in T::sample::<_>() {
res += fmap_respects_identity::<T, _, _>(|| pa(2));
}
for pa in T::sample::<_>() {
res += fmap_respects_composition::<T, _, _, _, _, _, _>(|x| x + 5, |x| x + 3, || pa(2));
}
res
}
#[test]
fn fmap_respects_identity() {
tests::fmap_respects_identity::<T, _, _>(|| None::<i32>);
tests::fmap_respects_identity::<T, _, _>(|| Some(1));
pub fn applicative_follows_laws<T: Applicative + FunctorTestSuite>() -> R
where
T::F<i32>: Debug + PartialEq,
{
let mut res = functor_follows_laws::<T>();
for pa in T::sample::<_>() {
res += seq_respects_identity::<T, _, _>(|| pa(2));
}
for pa in T::sample::<_>() {
for pg in T::sample::<_>() {
for pf in T::sample::<_>() {
res += seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| pf(|x| x + 5),
|| pg(|x| x + 3),
|| pa(2),
);
}
}
}
res += seq_is_homomorphic::<T, _, _, _, _>(|x| x + 3, || 2);
for pf in T::sample::<_>() {
res += seq_respects_interchange::<T, _, _, _, _, _>(|| pf(|x| x + 3), || 2);
}
for pa in T::sample::<_>() {
for pf in T::sample::<_>() {
res += seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(|| pf(|x| x + 3), || pa(2));
}
}
for pa in T::sample::<_>() {
res += fmap_can_be_expressed_via_seq::<T, _, _, _, _>(|x| x + 3, || pa(2));
}
for pa in T::sample::<_>() {
for pb in T::sample::<_>() {
res += discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(|| pa(2), || pb(2));
}
}
res
}
#[test]
fn fmap_respects_composition() {
tests::fmap_respects_composition::<T, _, _, _, _, _, _>(
|x| x + 5,
|x| x + 3,
|| None::<i32>,
);
tests::fmap_respects_composition::<T, _, _, _, _, _, _>(|x| x + 5, |x| x + 3, || Some(2));
}
#[test]
fn replace_none_b_is_none() {
assert_eq!(T::replace(None::<i32>, 1), None);
assert_eq!(T::void(None::<i32>), None);
}
#[test]
fn replace_some_a_b_is_some_b() {
assert_eq!(T::replace(Some(1), 2), Some(2));
assert_eq!(T::void(Some(1)), Some(()));
}
#[test]
fn seq_respects_identity() {
tests::seq_respects_identity::<T, _, _>(|| None::<i32>);
tests::seq_respects_identity::<T, _, _>(|| Some(1));
}
#[test]
fn seq_respects_composition() {
tests::seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| Some(|x| x + 5),
|| Some(|x| x + 3),
|| Some(2),
);
tests::seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| tests::make_none(Some(|x| x + 5)),
|| Some(|x| x + 3),
|| Some(2),
);
tests::seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| Some(|x| x + 5),
|| tests::make_none(Some(|x| x + 3)),
|| Some(2),
);
tests::seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| Some(|x| x + 5),
|| Some(|x| x + 3),
|| None::<i32>,
);
tests::seq_respects_composition::<T, _, _, _, _, _, _, _, _>(
|| tests::make_none(Some(|x| x + 5)),
|| tests::make_none(Some(|x| x + 3)),
|| None::<i32>,
);
}
#[test]
fn seq_is_homomorphic() {
tests::seq_is_homomorphic::<T, _, _, _, _>(|x| x + 3, || 2);
}
#[test]
fn seq_respects_interchange() {
tests::seq_respects_interchange::<T, _, _, _, _, _>(|| Some(|x| x + 3), || 2);
tests::seq_respects_interchange::<T, _, _, _, _, _>(|| make_none(Some(|x| x + 3)), || 2);
}
#[test]
fn seq_can_be_expressed_via_la2() {
tests::seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(|| Some(|x| x + 3), || Some(2));
tests::seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(
|| make_none(Some(|x| x + 3)),
|| Some(2),
);
tests::seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(|| Some(|x| x + 3), || None::<i32>);
tests::seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(
|| make_none(Some(|x| x + 3)),
|| None::<i32>,
);
}
#[test]
fn fmap_can_be_expressed_via_seq() {
tests::fmap_can_be_expressed_via_seq::<T, _, _, _, _>(|x| x + 3, || Some(2));
tests::fmap_can_be_expressed_via_seq::<T, _, _, _, _>(|x| x + 3, || None::<i32>);
}
#[test]
fn discard_can_be_expressed_via_seq_or_la2() {
tests::discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(|| Some(2), || Some(3));
tests::discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(|| Some(2), || None::<i32>);
tests::discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(|| None::<i32>, || Some(3));
tests::discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(
|| None::<i32>,
|| None::<i32>,
);
}
#[test]
fn bind_respects_left_identity() {
tests::bind_respects_left_identity::<T, _, _, _, _>(|x| Some(x + 3), || 2);
tests::bind_respects_left_identity::<T, _, _, _, _>(|_| None::<i32>, || 2);
}
#[test]
fn bind_respects_right_identity() {
tests::bind_respects_right_identity::<T, _, _>(|| Some(1));
tests::bind_respects_right_identity::<T, _, _>(|| None::<i32>);
}
#[test]
fn bind_is_associative() {
tests::bind_is_associative::<T, _, _, _, _, _, _>(
|x| Some(x + 5),
|x| Some(x + 3),
|| Some(2),
);
tests::bind_is_associative::<T, _, _, _, _, _, _>(
|_| None::<i32>,
|x| Some(x + 3),
|| Some(2),
);
tests::bind_is_associative::<T, _, _, _, _, _, _>(
|x| Some(x + 5),
|_| None::<i32>,
|| Some(2),
);
tests::bind_is_associative::<T, _, _, _, _, _, _>(
|x| Some(x + 5),
|x| Some(x + 3),
|| None::<i32>,
);
tests::bind_is_associative::<T, _, _, _, _, _, _>(
|_| None::<i32>,
|_| None::<i32>,
|| None::<i32>,
);
}
#[test]
fn seq_can_be_expressed_via_bind() {
tests::seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(|| Some(|x| x + 3), || Some(2));
tests::seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(
|| Some(|x| x + 3),
|| None::<i32>,
);
tests::seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(
|| make_none(Some(|x| x + 3)),
|| Some(2),
);
tests::seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(
|| make_none(Some(|x| x + 3)),
|| None::<i32>,
);
}
#[test]
fn fmap_can_be_expressed_via_bind() {
tests::fmap_can_be_expressed_via_bind::<T, _, _, _, _>(|x| x + 3, || Some(2));
tests::fmap_can_be_expressed_via_bind::<T, _, _, _, _>(|x| x + 3, || None::<i32>);
pub fn monad_follows_laws<T: Monad + FunctorTestSuite>() -> R
where
T::F<i32>: Debug + PartialEq,
{
let mut res = applicative_follows_laws::<T>();
for pa in T::sample::<_>() {
res += bind_respects_left_identity::<T, _, _, _, _>(|x| pa(x + 3), || 2);
}
for pa in T::sample::<_>() {
res += bind_respects_right_identity::<T, _, _>(|| pa(2));
}
for pa in T::sample::<_>() {
for pg in T::sample::<_>() {
for pf in T::sample::<_>() {
res += bind_is_associative::<T, _, _, _, _, _, _>(
|x| pf(x + 5),
|x| pg(x + 3),
|| pa(2),
);
}
}
}
for pa in T::sample::<_>() {
for pf in T::sample::<_>() {
res += seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(
|| pf(|x| x + 3),
|| pa(2),
);
}
}
for pa in T::sample::<_>() {
res += fmap_can_be_expressed_via_bind::<T, _, _, _, _>(|x| x + 3, || pa(2));
}
res
}
}

2
src/lib.rs
View File

@ -1,2 +1,4 @@
pub mod core;
pub mod func;
pub mod optionclass;
pub mod copy_func;

117
src/optionclass.rs Normal file
View File

@ -0,0 +1,117 @@
use crate::func::*;
pub struct OptionClass;
impl WeakFunctor for OptionClass {
type F<A> = Option<A>;
}
impl Functor for OptionClass {
fn fmap<A, B, F: FnOnce(A) -> B>(f: F, fa: Self::F<A>) -> Self::F<B> {
match fa {
Some(a) => Some(f(a)),
None => None,
}
}
fn replace<A, B>(fa: Self::F<A>, b: B) -> Self::F<B> {
match fa {
Some(_) => Some(b),
None => None,
}
}
}
impl ApplicativeSeq for OptionClass {
fn seq<A, B, F: FnOnce(A) -> B>(ff: Self::F<F>, fa: Self::F<A>) -> Self::F<B> {
match (ff, fa) {
(Some(f), Some(a)) => Some(f(a)),
_ => None,
}
}
}
impl ApplicativeLA2 for OptionClass {
fn la2<A, B, C, F: FnOnce(A, B) -> C>(f: F, fa: Self::F<A>, fb: Self::F<B>) -> Self::F<C> {
match (fa, fb) {
(Some(a), Some(b)) => Some(f(a, b)),
_ => None,
}
}
}
impl Applicative for OptionClass {
fn pure<A>(a: A) -> Self::F<A> {
Some(a)
}
fn discard_first<A, B>(fa: Self::F<A>, fb: Self::F<B>) -> Self::F<B> {
match fa {
Some(_) => fb,
None => None,
}
}
fn discard_second<A, B>(fa: Self::F<A>, fb: Self::F<B>) -> Self::F<A> {
match fb {
Some(_) => fa,
None => None,
}
}
}
impl Monad for OptionClass {
fn bind<A, B, F: FnOnce(A) -> Self::F<B>>(fa: Self::F<A>, f: F) -> Self::F<B> {
match fa {
Some(a) => f(a),
None => None,
}
}
fn join<A>(ffa: Self::F<Self::F<A>>) -> Self::F<A> {
match ffa {
Some(Some(a)) => Some(a),
_ => None,
}
}
}
#[cfg(test)]
mod option_tests {
use super::test_suite;
use super::{Functor, OptionClass as T};
impl test_suite::FunctorTestSuite for T {
fn sample<A>() -> Vec<Box<dyn Fn(A) -> Self::F<A>>> {
vec![Box::new(|_| None), Box::new(|a| Some(a))]
}
}
#[test]
fn fmap_f_none_is_none() {
assert_eq!(T::fmap(|_: ()| (), None), None);
}
#[test]
fn fmap_f_some_a_is_some_f_a() {
assert_eq!(T::fmap(|x| x * x, Some(2)), Some(4));
}
#[test]
fn replace_none_b_is_none() {
assert_eq!(T::replace(None::<i32>, 1), None);
assert_eq!(T::void(None::<i32>), None);
}
#[test]
fn replace_some_a_b_is_some_b() {
assert_eq!(T::replace(Some(1), 2), Some(2));
assert_eq!(T::void(Some(1)), Some(()));
}
#[test]
fn monad_follows_laws() {
test_suite::monad_follows_laws::<T>().unwrap();
}
}