wip: fix(dsl): maybe getting somewhere?

output/src/ops/_reduce.rs

@@ -0,0 +1,93 @@
+use crate::*;
+
+pub struct Reduce<A, B, I, F, G>(pub PhantomData<A>, pub F, pub G) where
+    A: Send + Sync, B: Send + Sync,
+    I: Iterator<Item = B> + Send + Sync,
+    F: Fn() -> I + Send + Sync,
+    G: Fn(A, B, usize)->A + Send + Sync;
+
+impl<A, B, I, F, G> Reduce<A, B, I, F, G> where
+    A: Send + Sync, B: Send + Sync,
+    I: Iterator<Item = B> + Send + Sync,
+    F: Fn() -> I + Send + Sync,
+    G: Fn(A, B, usize)->A + Send + Sync
+{
+    pub const fn new (f: F, g: G) -> Self { Self(Default::default(), f, g) }
+}
+
+impl<E: Output, A, B, I, F, G> Content<E> for Reduce<A, B, I, F, G> where
+    A: Send + Sync, B: Send + Sync,
+    I: Iterator<Item = B> + Send + Sync,
+    F: Fn() -> I + Send + Sync,
+    G: Fn(A, B, usize)->A + Send + Sync
+{
+    fn content (&self) -> impl Render<E> {
+    }
+}
+
+/*
+
+    //pub fn reduce <E, T, I, R, F>(iterator: I, callback: F) -> Reduce<E, T, I, R, F> where
+        //E: Output,
+        //I: Iterator<Item = T> + Send + Sync,
+        //R: Render<E>,
+        //F: Fn(R, T, usize) -> R + Send + Sync
+    //{
+        //Reduce(Default::default(), iterator, callback)
+    //}
+pub struct Reduce<E, T, I, R, F>(PhantomData<(E, R)>, I, F) where
+    E: Output,
+    I: Iterator<Item = T> + Send + Sync,
+    R: Render<E>,
+    F: Fn(R, T, usize) -> R + Send + Sync;
+impl<E, T, I, R, F> Content<E> for Reduce<E, T, I, R, F> where
+    E: Output,
+    I: Iterator<Item = T> + Send + Sync,
+    R: Render<E>,
+    F: Fn(R, T, usize) -> R + Send + Sync
+{
+    fn render (&self, to: &mut E) {
+        todo!()
+    }
+}
+*/
+
+//macro_rules! define_ops {
+    //($Trait:ident<$E:ident:$Output:path> { $(
+        //$(#[$attr:meta $($attr_args:tt)*])*
+        //(
+            //$fn:ident
+            //$(<$($G:ident$(:$Gen:path)?, )+>)?
+            //$Op:ident
+            //($($arg:ident:$Arg:ty),*)
+        //)
+    //)* }) => {
+        //impl<$E: $Output> $Trait<E> for E {}
+        //pub trait $Trait<$E: $Output> {
+            //$(
+                //$(#[$attr $($attr_args)*])*
+                //fn $fn $(<$($G),+>)?
+                //($($arg:$Arg),*)-> $Op<$($(, $G)+)?> 
+                //$(where $($G: $($Gen + Send + Sync)?),+)?
+                //{ $Op($($arg),*) }
+            //)*
+        //}
+    //}
+//}
+
+//define_ops! {
+    //Layout<E: Output> {
+        //(when <A: Render<E>,>
+            //When(cond: bool, item: A))
+        ///// When `cond` is `true`, render `a`, otherwise render `b`.
+        //(either <A: Render<E>, B: Render<E>,>
+            //Either(cond: bool, a: A, b: B))
+        ///// If `opt` is `Some(T)` renders `cb(t)`, otherwise nothing.
+        //(opt <A, F: Fn(A) -> B, B: Render<E>,>
+            //Opt(option: Option<A>, cb: F))
+        ///// Maps items of iterator through callback.
+        //(map <A, B: Render<E>, I: Iterator<Item = A>, F: Fn() -> I, G: Fn(A, usize)->B,>
+            //Map(get_iterator: F, callback: G))
+    //}
+//}
+