unexpected result for creating directory tree using callProcess or callCommand

[pucsdian]

shell command :-

mkdir -p ./{new/{new1,new2},old}

tested with :-

callProcess "mkdir" ["-p" , "./{new/{new1,new2},old}"]
callCommand "mkdir -p ./{new/{new1,new2},old}"

result :-

.
├── {new
│ └── {new1,new1},old}

expected output :-

tree .
.
├── new
│   ├── new1
│   └── new1
└── old

I printed shell command with :-
showCommandForUser "mkdir" ["-p" , "./{new/{new1,new2},old}"]

output :- "mkdir -p './{new/{new1,new2},old}'"

this single single quotes around directory name causing problem
how can i fix this

[joehealy]

The {} syntax is brace expansion from bash (https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#Brace-Expansion). You will need to run your expression through bash to get the behavior you are after.