An input port can be created in many ways, but usually the method starts with open-input-
.
You can use a string as a port using open-input-string
. It will create a port that will be able to read from the string.
(define p
(open-input-string "(a . (b . (c . ()))) 34"))
You can open a file for reading with open-input-file
.
(define p
(open-input-file "path/to/file"))