[PATCH 1/2] gwl/workflows: Execute independent processes in parallel

[Olivier Dion <olivier.dion@polymtl.ca>]

Processes in the same list can be executed in parallel with `par-map'.  The
results are then appended to the accumulator.
---
 gwl/workflows.scm | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/gwl/workflows.scm b/gwl/workflows.scm
index 03b29e0..74a1c74 100644
--- a/gwl/workflows.scm
+++ b/gwl/workflows.scm
@@ -43,6 +43,7 @@
 
   #:use-module (ice-9 match)
   #:use-module (ice-9 format)
+  #:use-module (ice-9 threads)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-9 gnu)
   #:use-module (srfi srfi-11)
@@ -447,13 +448,12 @@ can be used in a fold over a WORKFLOW's processes."
   (lambda (item acc)
     (match item
       ((? list?)
-       (fold (lambda (process res)
-               (cons (proc process) res))
-             acc
-             ;; By reversing the order of the processes
-             ;; in STEP we keep the output order the same
-             ;; as the order of the sequential function.
-             (reverse item)))
+       (append
+        ;; By reversing the order of the processes
+        ;; in STEP we keep the output order the same
+        ;; as the order of the sequential function.
+        (par-map (cut proc <>) (reverse item))
+        acc))
       (_ (cons (proc item) acc)))))
 
 (define* (workflow-prepare workflow engine
-- 
2.36.1