Pass the output type of tforeach positionally

CHANGELOG.md

@@ -1,6 +1,10 @@
 OhMyThreads.jl Changelog
 =========================
 
+Version 0.8.9
+------------
+- ![Enhancement][badge-enhancement] `tforeach` no longer compiles a scheduler's implementation for every output type: its output type (`Nothing`) is now passed on as a constant, instead of a `DataType` in the keyword arguments. With schedulers that compile a reduction only when there is a result, this saves the compilation of the reduction for every loop body [#177][gh-pr-177].
+
 Version 0.8.8
 ------------
 - ![Enhancement][badge-enhancement] `tforeach`, `treduce`, `treducemap`, `tmap`, `tmap!`, and `tmapreduce` now always specialize on the function arguments. Before, a call could run through an instance compiled for `f::Function`, and dispatch every call of `f` dynamically, e.g. `tforeach(_ -> work(n), xs)` with a non-inlined `work` and a run-time `n` [#176][gh-pr-176].
@@ -196,3 +200,4 @@ Version 0.2.0
 [gh-pr-173]: https://github.com/JuliaFolds2/OhMyThreads.jl/pull/173
 [gh-pr-174]: https://github.com/JuliaFolds2/OhMyThreads.jl/pull/174
 [gh-pr-176]: https://github.com/JuliaFolds2/OhMyThreads.jl/pull/176
+[gh-pr-177]: https://github.com/JuliaFolds2/OhMyThreads.jl/pull/177

Project.toml

@@ -1,7 +1,7 @@
 name = "OhMyThreads"
 uuid = "67456a42-1dca-4109-a031-0a68de7e3ad5"
 authors = ["Carsten Bauer <mail@carstenbauer.eu>", "Mason Protter <mason.protter@icloud.com>"]
-version = "0.8.8"
+version = "0.8.9"
 
 [deps]
 BangBang = "198e06fe-97b7-11e9-32a5-e1d131e6ad66"

src/implementation.jl

@@ -91,6 +91,16 @@ end
         outputtype::Type = Any,
         init = NotGiven(),
         kwargs...) where {F, OP}
+    return tmapreduce_positional(f, op, Arrs, outputtype, scheduler, init, kwargs)
+end
+
+# `tmapreduce` with the output type as a positional argument: passed through keyword
+# arguments, a type is stored as a `DataType`, and the parallel implementation is then
+# compiled for every output type at once (for `tforeach`, also the reduction it never does).
+# No type parameter: an output type only known at run time would then be dispatched on
+# before the serial fallback; `_tmapreduce` specializes on it instead.
+@inline function tmapreduce_positional(f::F, op::OP, Arrs, outputtype::Type,
+        scheduler, init, kwargs) where {F, OP}
     mapreduce_kwargs = isgiven(init) ? (; init) : (;)
     _scheduler = _scheduler_from_userinput(scheduler; kwargs...)
 
@@ -462,8 +472,10 @@ end
 
 #-------------------------------------------------------------
 
-function tforeach(f::F, A...; kwargs...)::Nothing where {F}
-    tmapreduce(f, (l, r) -> l, A...; kwargs..., init = nothing, outputtype = Nothing)
+function tforeach(f::F, A...; scheduler::MaybeScheduler = NotGiven(),
+        init = nothing, outputtype::Type = Nothing, kwargs...)::Nothing where {F}
+    tmapreduce_positional(f, (l, r) -> l, A, Nothing, scheduler, nothing, kwargs)
+    return nothing
 end
 
 #-------------------------------------------------------------