stdlib: Add is-ignored predicate

diff --git a/stdlib/prelude.gl b/stdlib/prelude.gl
index 32adf5c..a2d804d 100644 (file)
--- a/stdlib/prelude.gl
+++ b/stdlib/prelude.gl
@@ -37,6 +37,9 @@ predicate is-file-exists (filename) = @{
     test -f %filename || exit 99
 }
 
+# Ignore parameter and always resolve to not rebuilding.
+predicate is-ignored (s) = @{ exit 0 }
+
 #----------------------------------------------------------------------
 # Basic functions.