Issue #127 - Allow cond-expand to check for libs

CHANGELOG.md

@@ -5,8 +5,9 @@ TODO: SRFI 113
 
 Features:
 
-- Thanks to ecraven, added `exact-integer-sqrt`.
+- Thanks to ecraven, added R7RS function `exact-integer-sqrt` to `(scheme base)`.
 - Allow the reader to recognize `+inf.0`, `-inf.0`, `+nan.0`, and `-nan.0`.
+- Allow `cond-expand` to test for whether a library exists using the form `(library {library name})`.
 
 Bug Fixes
 

scheme/base.sld

@@ -316,13 +316,12 @@
       (er-macro-transformer
         ;; Based on the cond-expand macro from Chibi scheme
         (lambda (expr rename compare)
-;; TODO: port to this macro, so we can use below for library form
+          (define (_library-exists? import . ext)
-(define (_library-exists? import . ext)
             (file-exists?
               (_lib:import->filename 
                 (_lib:import->library-name import)
                 (if (null? ext) ".sld" (car ext)))))
-(define (_lib:import->filename import . ext)
+          (define (_lib:import->filename import . ext)
             (let* ((file-ext 
                     (if (null? ext)
                         ".sld"
@@ -347,7 +346,7 @@
                       (equal? 'srfi   (car import)))
                 (string-append (Cyc-installation-dir 'sld) "/" filename) ;; Built-in library
                 filename)))
-(define (_lib:import->library-name import)
+          (define (_lib:import->library-name import)
             (cond
               ((and (pair? import)
                     (or (equal? 'only   (car import))