Thanks to C-Keen (IRC). 

Change (import curl) to (use curl) in the repl.  

- import just imports the namespace but does not load code
- For compiled code is better to use "use" instead of "import"

#;1> (use curl)
; loading ./curl.import.so ...
; loading /usr/local/lib/chicken/7/chicken.import.so ...
; loading /usr/local/lib/chicken/7/foreign.import.so ...
; loading ./sclj.import.scm ...
; loading /usr/local/lib/chicken/7/ports.import.so ...
; loading /usr/local/lib/chicken/7/srfi-4.import.so ...
; loading /usr/local/lib/chicken/7/extras.import.so ...
; loading /usr/local/lib/chicken/7/lolevel.import.so ...
; loading /usr/local/lib/chicken/7/easyffi.import.so ...
; loading ./curl.so ...

Note: the following toplevel variables are referenced but unbound:

  plist-vals
  plist-keys
  plist->alist
#;2> (curl-get "http://httpbin.org/get")
"{\n  \"args\": {}, \n  \"headers\": {\n    \"Accept\": \"*/*\", \n    \"Host\": \"httpbin.org\", \n    \"User-Agent\": \"Mozzila/4.0\"\n  }, \n  \"origin\": \"174.172.155.241\", \n  \"url\": \"http://httpbin.org/get\"\n}\n"
#;3>