some docs + clippy fixes

src/func.rs

@@ -10,6 +10,46 @@ pub trait WeakFunctor {
     type F<'a, A>;
 }
 
+/// Rust-specific implementation of [Functor], respecting `move` semantics.
+/// 
+/// Cannot insantiate for e.g. multi-element collections:
+/// ```compile_fail
+/// use radn_rs::func::*;
+///
+/// struct VecClass;
+///
+/// impl WeakFunctor for VecClass {
+///     type F<'a, A> = Vec<A>;
+/// }
+///
+/// impl Functor for VecClass {
+///     fn fmap<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> B>(f: F, fa: Self::F<'a, A>) -> Self::F<'a, B> {
+///         fa.into_iter().map(f).collect()
+///     }
+/// }
+/// ```
+/// Why does it fail to compile? `.map` expects `FnMut` (or we can think of it being `Fn`, doesn't matter here). But what we provide it (`f`) is 
+/// 
+/// For Haskell-style Functors, use [clone_func::CloneFunctor] instead.
+/// ```
+/// use radn_rs::func::clone_func::*;
+///
+/// struct VecClass;
+///
+/// impl CloneWeakFunctor for VecClass {
+///     type ClF<'a, A: Clone> = Vec<A>;
+/// }
+///
+/// impl CloneFunctor for VecClass {
+///     fn clone_fmap<'a, A: 'a + Clone, B: 'a + Clone, F: 'a + Fn(A) -> B>(
+///         f: F,
+///         fa: Self::ClF<'a, A>,
+///     ) -> Self::ClF<'a, B> {
+///         fa.into_iter().map(f).collect()
+///     }
+/// }
+/// ```
+
 pub trait Functor: WeakFunctor {
     fn fmap<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> B>(f: F, fa: Self::F<'a, A>) -> Self::F<'a, B>;
 

src/func/classes/optionclass.rs

@@ -8,17 +8,11 @@ impl WeakFunctor for OptionClass {
 
 impl Functor for OptionClass {
     fn fmap<'a, A: 'a, B: 'a, F: 'a + FnOnce(A) -> B>(f: F, fa: Self::F<'a, A>) -> Self::F<'a, B> {
-        match fa {
-            Some(a) => Some(f(a)),
-            None => None,
-        }
+        fa.map(f)
     }
 
     fn replace<'a, A: 'a, B: 'a>(fa: Self::F<'a, A>, b: B) -> Self::F<'a, B> {
-        match fa {
-            Some(_) => Some(b),
-            None => None,
-        }
+        fa.map(|_| b)
     }
 }
 

src/func/classes/soloclass.rs

@@ -18,7 +18,6 @@ impl Functor for SoloClass {
 
     fn void<'a, A: 'a>(fa: Self::F<'a, A>) -> Self::F<'a, ()> {
         drop(fa);
-        ()
     }
 }
 

src/func/clone_func.rs

@@ -67,7 +67,7 @@ pub trait CloneApplicativeSeq: CloneFunctor {
             Self::clone_fmap(
                 move |a| {
                     let cf = f.clone();
-                    move |b: B| cf(a.clone(), b.clone())
+                    move |b: B| cf(a.clone(), b)
                 },
                 fa,
             ),