WIP: add FirstX (TODO: add tests)

Author: fingolfin

lib/coll.gd

@@ -2504,6 +2504,7 @@ DeclareGlobalFunction( "FoldLeftX" );
 DeclareGlobalFunction( "ForAllX" );
 DeclareGlobalFunction( "ForAnyX" );
 DeclareGlobalFunction( "FilteredX" );
+DeclareGlobalFunction( "FirstX" );
 DeclareGlobalFunction( "NumberX" );
 DeclareGlobalFunction( "PerformX" );
 

lib/coll.gi

@@ -1849,7 +1849,7 @@ end );
 InstallGlobalFunction( ForAllX, function ( arg )
     local f;
     f := Remove(arg);
-    return FoldLeftX(arg, {acc,x} -> acc and CallFuncList(f, x), true, false);
+    return FoldLeftX(arg, {acc,x} -> CallFuncList(f, x), true, false);
 end );
 
 
@@ -1860,7 +1860,26 @@ end );
 InstallGlobalFunction( ForAnyX, function ( arg )
     local f;
     f := Remove(arg);
-    return FoldLeftX(arg, {acc,x} -> acc or CallFuncList(f, x), false, true);
+    return FoldLeftX(arg, {acc,x} -> CallFuncList(f, x), false, true);
+end );
+
+
+#############################################################################
+##
+#M  FirstX(<obj>,...)
+##
+InstallGlobalFunction( FirstX, function ( arg )
+    local f, result;
+    f := Remove(arg);
+    return FoldLeftX(arg,
+            function(acc, x)
+                if CallFuncList(f, x) then
+                    result := x;
+                    return true;
+                fi;
+                return false;
+            end, false, true);
+    return result;
 end );