new test sample

src/func.rs

@@ -1,8 +1,9 @@
 pub mod classes;
-#[cfg(test)]
-pub mod tests;
+pub mod copy_func;
 #[cfg(test)]
 pub mod test_suite;
+#[cfg(test)]
+pub mod tests;
 
 pub trait WeakFunctor {
     type F<'a, A>;
@@ -73,4 +74,3 @@ pub trait Monad: Applicative {
         Self::bind(ffa, |fa| fa)
     }
 }
-

src/func/classes.rs

@@ -1,2 +1,3 @@
 pub mod optionclass;
 pub mod futureclass;
+pub mod soloclass;

src/func/classes/futureclass.rs

@@ -1,7 +1,5 @@
 use std::{future::Future, pin::Pin};
 
-// use futures::FutureExt;
-
 use futures::join;
 
 use crate::func::*;
@@ -56,28 +54,26 @@ impl Applicative for FutureClass {
     }
 
     fn discard_first<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, fb: Self::F<'a, B>) -> Self::F<'a, B> {
-        Box::pin(async {
-            join!(fa, fb).1
-        })
+        Box::pin(async { join!(fa, fb).1 })
     }
 
     fn discard_second<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, fb: Self::F<'a, B>) -> Self::F<'a, A> {
-        Box::pin(async {
-            join!(fa, fb).0
-        })
+        Box::pin(async { join!(fa, fb).0 })
     }
 }
 
 impl Monad for FutureClass {
-    fn bind<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> Self::F<'a, B>>(fa: Self::F<'a, A>, f: F) -> Self::F<'a, B> {
-        Box::pin(async{
-            f(fa.await).await
-        })
+    fn bind<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> Self::F<'a, B>>(
+        fa: Self::F<'a, A>,
+        f: F,
+    ) -> Self::F<'a, B> {
+        Box::pin(async { f(fa.await).await })
     }
 
-    fn join<'a, A: 'a>(ffa: Self::F<'a, Self::F<'a, A>>) -> Self::F<'a, A> where Self::F<'a, A>: 'a {
-        Box::pin(async{
-            ffa.await.await
-        })
+    fn join<'a, A: 'a>(ffa: Self::F<'a, Self::F<'a, A>>) -> Self::F<'a, A>
+    where
+        Self::F<'a, A>: 'a,
+    {
+        Box::pin(async { ffa.await.await })
     }
 }

src/func/classes/optionclass.rs

@@ -3,7 +3,7 @@ use crate::func::*;
 pub struct OptionClass;
 
 impl WeakFunctor for OptionClass {
-    type F<'_a, A> = Option<A>;
+    type F<'a, A> = Option<A>;
 }
 
 impl Functor for OptionClass {
@@ -106,8 +106,12 @@ mod option_tests {
     }
 
     impl test_suite::FunctorTestSuite for T {
-        fn sample<'a, A>() -> Vec<Box<dyn Fn(A) -> Self::F<'a, A>>> {
-            vec![Box::new(|_| None), Box::new(|a| Some(a))]
+        fn sample<'a, A: 'a, F: FnMut(&'a dyn Fn(A) -> Self::F<'a, A>)>(mut f: F)
+        where
+            Self::F<'a, A>: 'a,
+        {
+            f(&|_| None);
+            f(&|a| Some(a));
         }
     }
 

src/func/classes/soloclass.rs

@@ -0,0 +1,74 @@
+use crate::func::*;
+
+pub struct SoloClass;
+
+impl WeakFunctor for SoloClass {
+    type F<'a, A> = A;
+}
+
+impl Functor for SoloClass {
+    fn fmap<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> B>(f: F, fa: Self::F<'a, A>) -> Self::F<'a, B> {
+        f(fa)
+    }
+
+    fn replace<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, b: B) -> Self::F<'a, B> {
+        drop(fa);
+        b
+    }
+
+    fn void<'a, A: 'a>(fa: Self::F<'a, A>) -> Self::F<'a, ()> {
+        drop(fa);
+        ()
+    }
+}
+
+impl ApplicativeSeq for SoloClass {
+    fn seq<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> B>(
+        ff: Self::F<'a, F>,
+        fa: Self::F<'a, A>,
+    ) -> Self::F<'a, B> {
+        ff(fa)
+    }
+}
+
+impl ApplicativeLA2 for SoloClass {
+    fn la2<'a, A: 'a, B: 'a, C: 'a, F: 'a + FnOnce(A, B) -> C>(
+        f: F,
+        fa: Self::F<'a, A>,
+        fb: Self::F<'a, B>,
+    ) -> Self::F<'a, C> {
+        f(fa, fb)
+    }
+}
+
+impl Applicative for SoloClass {
+    fn pure<'a, A: 'a>(a: A) -> Self::F<'a, A> {
+        a
+    }
+
+    fn discard_first<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, fb: Self::F<'a, B>) -> Self::F<'a, B> {
+        drop(fa);
+        fb
+    }
+
+    fn discard_second<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, fb: Self::F<'a, B>) -> Self::F<'a, A> {
+        drop(fb);
+        fa
+    }
+}
+
+impl Monad for SoloClass {
+    fn bind<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> Self::F<'a, B>>(
+        fa: Self::F<'a, A>,
+        f: F,
+    ) -> Self::F<'a, B> {
+        f(fa)
+    }
+
+    fn join<'a, A: 'a>(ffa: Self::F<'a, Self::F<'a, A>>) -> Self::F<'a, A>
+    where
+        Self::F<'a, A>: 'a,
+    {
+        ffa
+    }
+}

src/func/copy_func.rs

@@ -1,4 +1,4 @@
-use super::func::*;
+use crate::func::*;
 
 pub trait CopyWeakFunctor {
     type CF<'a, A: Copy>;

src/func/test_suite.rs

@@ -1,88 +1,85 @@
-use std::rc::Rc;
-
 use super::{tests::*, *};
 
-pub trait FunctorTestSuite: WeakFunctor + Eqr {
-    fn sample<'a, A>() -> Vec<Box<dyn 'a + Fn(A) -> Self::F<'a, A>>>;
+pub trait FunctorTestSuite: WeakFunctor + Eqr + 'static {
+    fn sample<'a, A: 'a, F: FnMut(&'a dyn Fn(A) -> Self::F<'a, A>)>(f: F)
+    where
+        Self::F<'a, A>: 'a;
 }
 
 pub fn functor_follows_laws<T: Functor + FunctorTestSuite>() -> R {
     let mut res = R::default();
-    for pa in T::sample::<_>() {
+    T::sample(|pa| {
         res += fmap_respects_identity::<T, _, _>(|| pa(2));
-    }
-    for pa in T::sample::<_>() {
+    });
+    T::sample(|pa| {
         res += fmap_respects_composition::<T, _, _, _, _, _, _>(|x| x + 5, |x| x + 3, || pa(2));
-    }
+    });
     res
 }
 
 pub fn applicative_follows_laws<T: Applicative + FunctorTestSuite>() -> R {
     let mut res = functor_follows_laws::<T>();
-    for pa in T::sample::<_>() {
+    T::sample(|pa| {
         res += seq_respects_identity::<T, _, _>(|| pa(2));
-    }
-    for pa in T::sample::<_>() {
-        for pg in T::sample::<_>() {
-            for pf in T::sample::<_>() {
+    });
+    T::sample(|pa| {
+        T::sample(|pg| {
+            T::sample(|pf| {
                 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::<_>() {
+    T::sample(|pf| {
         res += seq_respects_interchange::<T, _, _, _, _, _>(|| pf(|x| x + 3), || 2);
-    }
-    for pa in T::sample::<_>() {
-        for pf in T::sample::<_>() {
+    });
+    T::sample(|pa| {
+        T::sample(|pf| {
             res += seq_can_be_expressed_via_la2::<T, _, _, _, _, _>(|| pf(|x| x + 3), || pa(2));
-        }
-    }
-    for pa in T::sample::<_>() {
+        })
+    });
+    T::sample(|pa| {
         res += fmap_can_be_expressed_via_seq::<T, _, _, _, _>(|x| x + 3, || pa(2));
-    }
-    for pa in T::sample::<_>() {
-        for pb in T::sample::<_>() {
+    });
+    T::sample(|pa| {
+        T::sample(|pb| {
             res += discard_can_be_expressed_via_seq_or_la2::<T, _, _, _, _>(|| pa(2), || pb(2));
-        }
-    }
+        })
+    });
     res
 }
 
 pub fn monad_follows_laws<T: Monad + FunctorTestSuite>() -> R
 where {
     let mut res = applicative_follows_laws::<T>();
-    for pa in T::sample::<_>() {
-        res += bind_respects_left_identity::<T, _, _, _, _>(move |x| pa(x + 3), || 2);
-    }
-    for pa in T::sample::<_>() {
-        res += bind_respects_right_identity::<T, _, _>(move || pa(2));
-    }
-    for pa in T::sample::<_>() {
-        for pg in T::sample::<_>() {
-            let pgrc = Rc::new(pg);
-            for pf in T::sample::<_>() {
-                let pgrci = pgrc.clone();
-                let pfrc = Rc::new(pf);
+    T::sample(|pa| {
+        res += bind_respects_left_identity::<T, _, _, _, _>(|x| pa(x + 3), || 2);
+    });
+    T::sample(|pa| {
+        res += bind_respects_right_identity::<T, _, _>(|| pa(2));
+    });
+    T::sample(|pa| {
+        T::sample(|pg| {
+            T::sample(|pf| {
                 res += bind_is_associative::<T, _, _, _, _, _, _>(
-                    move |x| pfrc(x + 5),
-                    move |x| pgrci(x + 3),
+                    |x| pf(x + 5),
+                    |x| pg(x + 3),
                     || pa(2),
                 );
-            }
-        }
-    }
-    for pf in T::sample::<_>() {
-        for pa in T::sample::<_>() {
-            seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(|| pf(|x| x + 3), move || pa(2));
-        }
-    }
-    for pa in T::sample::<_>() {
-        res += fmap_can_be_expressed_via_bind::<T, _, _, _, _>(|x| x + 3, move || pa(2));
-    }
+            })
+        })
+    });
+    T::sample(|pa| {
+        T::sample(|pf| {
+            seq_can_be_expressed_via_bind::<T, _, _, _, _, _>(|| pf(|x| x + 3), || pa(2));
+        })
+    });
+    T::sample(|pa| {
+        res += fmap_can_be_expressed_via_bind::<T, _, _, _, _>(|x| x + 3, || pa(2));
+    });
     res
 }

src/lib.rs

@@ -1,3 +1,3 @@
-pub mod copy_func;
 pub mod core;
 pub mod func;
+mod xrcs;

src/xrcs.rs

@@ -0,0 +1,63 @@
+/// Solutions to some exercises by Alisa Feistel.
+/// Included here for their relevance to the whole Monad theme.
+#[cfg(test)]
+mod tests {
+    fn bind<T, F: FnOnce(T) -> Option<T>>(f: F, fa: Option<T>) -> Option<T> {
+        match fa {
+            Some(a) => f(a),
+            None => None,
+        }
+    }
+
+    #[test]
+    fn test() {
+        assert_eq!(bind(|x: i32| Some(x + 3), Some(2)), Some(5));
+        assert_eq!(bind(|x: i32| Some(x + 3), None), None);
+        assert_eq!(bind(|_: i32| None, Some(2)), None);
+        assert_eq!(bind(|_: i32| None, None), None);
+
+        assert_eq!(bind(|x: &str| Some(x), Some("apple")), Some("apple"));
+        assert_eq!(
+            bind(|_: &str| Some("banana"), Some("apple")),
+            Some("banana")
+        );
+
+        let banana = "banana".to_string();
+        assert_eq!(
+            bind(|_: &str| Some(banana.as_str()), Some("apple")),
+            Some("banana")
+        );
+
+        let banana = "banana".to_string();
+        assert_eq!(
+            bind(|_: String| Some(banana), Some("apple".to_string())),
+            Some("banana".to_string())
+        );
+    }
+}
+
+#[cfg(test)]
+mod reftests {
+    fn refbind<'a, 'b, T: 'a + ?Sized, F: 'a + Fn(&'a T) -> Option<&'b T>>(
+        f: F,
+        fa: Option<&'a T>,
+    ) -> Option<&'b T> {
+        match fa {
+            Some(a) => f(a),
+            None => None,
+        }
+    }
+
+    #[test]
+    fn test() {
+        let apple = "apple".to_string();
+        let banana = "banana".to_string();
+        assert_eq!(
+            refbind(|_: &String| Some(&banana), Some(&apple)),
+            Some(&banana)
+        );
+
+        let banana = "banana";
+        assert_eq!(refbind(|_: &str| Some(banana), Some("apple")), Some(banana));
+    }
+}