update docstring for kwarg N

src/parallel.jl

@@ -10,7 +10,8 @@ Declare the `kernel` parallel and containing stencil computations be performed w
 - `inbounds::Bool`: whether to apply `@inbounds` to the kernel. The default is `false` or as set with the `inbounds` keyword argument of [`@init_parallel_stencil`](@ref).
 - `memopt::Bool=false`: whether to perform advanced stencil-specific on-chip memory optimisations. If `memopt=true` is set, then it must also be set in the corresponding kernel call(s).
 !!! note "Advanced optional keyword arguments"
-    - `ndims::Integer|Tuple`: the number of dimensions used for the stencil computations in the kernels: 1, 2 or 3 (or a tuple containing any of the previous in order to generate a method for each of the given values - this can only work correctly if the macros used *and loaded* work for any of the chosen values of `ndims`!). A default can be set with the `ndims` keyword argument of [`@init_parallel_stencil`](@ref). The value of `ndims` can be interpolated into the kernel method signatures with `\$ndims` (e.g., `@parallel ndims=(1,3) function f(A::Data.Array{\$ndims}) ... end`). This enables dispatching on the number of dimensions in the kernel methods.
+    - `ndims::Integer|Tuple`: the number of dimensions used for the stencil computations in the kernels: 1, 2 or 3 (or a tuple containing any of the previous in order to generate a method for each of the given values - this can only work correctly if the macros used *and loaded* work for any of the chosen values of `ndims`!). A default can be set with the `ndims` keyword argument of [`@init_parallel_stencil`](@ref). The keyword argument `N` becomes mandatory when `ndims` is a tuple in order to dispatch on the number of dimensions (see below).
+    - `N::Integer|Tuple`: the value(s) a type parameter `N` in the kernel method signatures must take. The values are typically computed based on `ndims` (set with the corresponding keyword argument of the `@parallel` macro or `@init_parallel_stencil`), which will be substituted in the expression before evaluating it. This enables dispatching on the number of dimensions in the kernel methods (e.g., `@parallel ndims=(1,3) N=ndims function f(A::Data.Array{N}) ... end`). The keyword argument `N` is mandatory if `ndims` is a tuple and must then furthermore be a tuple of the same length as `ndims`.
 
 See also: [`@init_parallel_stencil`](@ref)
 
@@ -65,7 +66,8 @@ Declare the `kernel` parallel and generate the given parallel `indices` inside t
     - `inbounds::Bool`: whether to apply `@inbounds` to the kernel. The default is `false` or as set with the `inbounds` keyword argument of [`@init_parallel_stencil`](@ref).
     - `memopt::Bool=false`: whether to perform advanced stencil-specific on-chip memory optimisations. If `memopt=true` is set, then it must also be set in the corresponding kernel call(s).
     !!! note "Advanced optional keyword arguments"
-        - `ndims::Integer|Tuple`: the number of indexing dimensions desired when using splat syntax for the `indices`: 1, 2 or 3 (a default `ndims` value can be set with the corresponding keyword argument of [`@init_parallel_stencil`](@ref)), or a tuple containing any of the previous in order to generate a method for each of the given `ndims` values (e.g., `@parallel_indices (I...) ndims=(2,3)`). Concretely, the splat syntax generates a tuple of parallel indices (`I` in this example) where the length is given by the `ndims` value (`2` for the first method and `3` for the second method in this example). This makes it possible to write kernels that are agnostic to the number of dimensions (writing, e.g., `A[I...]` to access elements of the array `A`). The value of `ndims` can be interpolated into the kernel method signatures with `\$ndims` (e.g., `@parallel ndims=(1,3) function f(A::Data.Array{\$ndims}) ... end`). This enables dispatching on the number of dimensions in the kernel methods.
+        - `ndims::Integer|Tuple`: the number of indexing dimensions desired when using splat syntax for the `indices`: 1, 2, 3 (a default `ndims` value can be set with the corresponding keyword argument of [`@init_parallel_stencil`](@ref)) or a tuple containing any of the previous in order to generate a method for each of the given `ndims` values. Concretely, the splat syntax (e.g., `@parallel_indices (I...) ndims=(2,3) ...`) generates a tuple of parallel indices (`I` in this example) where the length is given by the `ndims` value (here `2` for the first method and `3` for the second). This makes it possible to write kernels that are agnostic to the number of dimensions (writing, e.g., `A[I...]` to access elements of the array `A`). The keyword argument `N` becomes mandatory when `ndims` is a tuple in order to dispatch on the number of dimensions (see below).
+        - `N::Integer|Tuple`: the value(s) a type parameter `N` in the kernel method signatures must take. The values are typically computed based on `ndims` (set with the corresponding keyword argument of the `@parallel_indices` macro or `@init_parallel_stencil`), which will be substituted in the expression before evaluating it. This enables dispatching on the number of dimensions in the kernel methods (e.g., `@parallel_indices (I...) ndims=(1,3) N=ndims function f(A::Data.Array{N}) ... end`). The keyword argument `N` is mandatory if `ndims` is a tuple and must then furthermore be a tuple of the same length as `ndims`.
 
 See also: [`@init_parallel_stencil`](@ref)
 """