Thanks again, again, again @urizenYHS3W , that did the trick.
But as expected, I am unable to troubleshoot the next line to get it to work.
I've tried modifying the expression to be able to get eval but not getting anywhere... all listed below.
I have very similar code I use successfully
STRING LIST $tr = extract($filter(folder('tool'), "type == '${t}' )",'tool')
but doesn't function as an ENTITY LIST.
Any additional help/guidance would be fantastic and greatly appreciated.
ENTITY LIST tools = folder('tool') OK
STRING LIST Tt_names = values(tools[0].Type) OK
STRING LIST Ttypes = apply(tools,'string(Type)') OK
INT old = remove_duplicates(Ttypes) OK
FOREACH t IN Ttypes { OK
ENTITY LIST tools_of_type = extract(filter(tools,'Type==t'),'Name') ORIGINAL PROVIDED CODE
ENTITY LIST tools_of_type = extract(filter(tools,'type==t'),'Name')
ENTITY LIST tools_of_type = extract(filter(tools,'Type == t'),'Name')
ENTITY LIST tools_of_type = extract(filter(tools,'type == t'),'Name')
ENTITY LIST tools_of_type = extract(filter('tools','Type==t'),'Name')
ENTITY LIST tools_of_type = extract(filter('tools','type==t'),'Name')
ENTITY LIST tools_of_type = extract(filter('tools','Type == t'),'Name')
ENTITY LIST tools_of_type = extract(filter('tools','type == t'),'Name')
ENTITY LIST tools_of_type = extract(filter('tools',"type == 't'"),'Name')
ENTITY LIST tools_of_type = extract(filter(folder('tool'),'Type==t'),'Name') with every variation above