Macro repeat 

macro_rules! repeat {
    ($name:ident<$T:ty> = {
        counter: $counter:expr,
        limit: $limit_var:expr,
        ops: [$($op:expr),+ $(,)?]
    }) => { ... };
    ($name:ident<$T:ty> = {
        counter: $counter:expr,
        limit: $limit_var:expr,
        continue_on_error: $continue_on_error:expr,
        ops: [$($op:expr),+ $(,)?]
    }) => { ... };
    ($name:ident<$T:ty> -> $strategy:ident = {
        counter: $counter:expr,
        limit: $limit_var:expr,
        ops: [$($op:expr),+ $(,)?]
    }) => { ... };
    ($name:ident<$T:ty> -> $strategy:ident = {
        counter: $counter:expr,
        limit: $limit_var:expr,
        continue_on_error: $continue_on_error:expr,
        ops: [$($op:expr),+ $(,)?]
    }) => { ... };
    (@strategy all) => { ... };
    (@strategy last) => { ... };
    (@strategy first) => { ... };
    (@strategy merge) => { ... };
    (@strategy unit) => { ... };
    (@impl $name:ident<$T:ty> -> all) => { ... };
    (@impl $name:ident<$T:ty> -> last) => { ... };
    (@impl $name:ident<$T:ty> -> first) => { ... };
    (@impl $name:ident<$T:ty> -> unit) => { ... };
    (@impl $name:ident<$T:ty> -> merge) => { ... };
}

Create a named for-loop op type with flexible return types The limit is loaded from a variable in the dry context Usage:

// Returns Vec<T> (default)
repeat! {
    ProcessLoop<String> = {
        counter: "iteration",
        limit: "max_iterations",
        ops: [StepOp::new(), LogOp::new()]
    }
}

// Returns T using last result
repeat! {
    ProcessLoop<String> -> last = {
        counter: "iteration",
        limit: "max_iterations",
        ops: [StepOp::new(), LogOp::new()]
    }
}