Polish the example a little bit

README.md

@@ -2,21 +2,39 @@
 Opinionated interface for creating shared libraries. Requires SBCL
 version >2.1.10.
 
-After loading this system, you can build the example library like this:
 
-`sbcl --eval "(progn (asdf:load-system :sbcl-librarian) (load \"libcalc.lisp\"))"`
+## Building the example
 
-which produces a header file, a source file, and a core file, and then you can compile the artifacts like so with:
+In the `example/` directory there is a full example shown. It is
+assumed sbcl-librarian is cloned in your local-projects directory so
+it is visible to asdf. For example if you are using roswell:
 
-`gcc -c -fpic libcalc.c`
+```
+$ cd ~/.roswell/local-projects/
+$ git clone https://github.com/quil-lang/sbcl-librarian
+```
 
-`gcc -shared libcalc.o -o libcalc.so -lsbcl`
+the user needs to have the SBCL shared library built. To do so one
+needs to run the `make-shared-libarary.sh` script. For roswell users
+(at tha time of writing the lates SBCL version is 2.2.2):
 
-`gcc example.c -o example -lsbcl -lcalc -L.`
 
-which creates a shared library and executable using the functions
-defined in the example system, assuming you have `libsbcl.so` and
-`libcalc.so` in a shared library path somewhere.
+```
+$ cd ~/.roswell/src/sbcl-2.2.2/
+$ ./make-shared-library.sh
+```
+
+Once that is done you are ready to build the example
+
+```
+$ make
+$ ./example
+> (+ 1 2)
+3
+```
+
+(in case there is a conflict related to build IDs see
+[issue](https://github.com/quil-lang/sbcl-librarian/issues/21#issuecomment-1068250667))
 
 NOTE: On Mac OS X you *MUST* specify `-pagezero_size 0x100000` when
 linking the final executable, otherwise SBCL will fail to mmap its

example/Makefile

@@ -1,11 +1,24 @@
 .PHONY: all clean
 
-all: libcalc.dylib
+SBCL_SRC=$(HOME)/.roswell/src/sbcl-2.2.2
+
+all: example
+
+example: example.c libcalc.dylib libsbcl.so
+	$(CC) example.c -L. -lsbcl -lcalc  -o $@
+
+# When missing you need to run ./make-shared-library.sh in sbcl
+# source.
+#
+# see: https://github.com/quil-lang/sbcl-librarian/issues/21#issuecomment-1068060794
+libsbcl.so: $(SBCL_SRC)/src/runtime/libsbcl.so
+	ln -s $< $@
 
 libcalc.core libcalc.c libcalc.h libcalc.py: libcalc.lisp
-	$(SBCL_SRC)/run-sbcl.sh --script "script.lisp"
+	ros run -l "script.lisp" -q
+#	$(SBCL) --script "script.lisp"
 
-libcalc.dylib: libcalc.core libcalc.c
-	$(CC) -dynamiclib -o $@ libcalc.c -L$(SBCL_SRC)/src/runtime -lsbcl
+libcalc.dylib: libcalc.core libcalc.c libsbcl.so
+	$(CC) -dynamiclib -o $@ libcalc.c -L. -lsbcl
 clean:
-	rm -f libcalc.c libcalc.h libcalc.core libcalc.py libcalc.dylib
+	rm -f libcalc.c libcalc.h libcalc.core libcalc.py libcalc.dylib example

example/example.py

@@ -35,4 +35,3 @@ def die(msg):
 
         libcalc.lisp_release_handle(expr)
         libcalc.lisp_release_handle(simplified)
-

example/libcalc.lisp

@@ -27,21 +27,21 @@
 (defun sum-expression-p (obj)
   (typep obj 'sum-expression))
 
+(defun parse-expr (lisp-expr)
+  (cond ((integerp lisp-expr)
+         (make-instance 'int-literal :value lisp-expr))
+        ((and (listp lisp-expr) (eq '+ (first lisp-expr)))
+         (let* ((left (parse-expr (second lisp-expr)))
+                (right (parse-expr (third lisp-expr))))
+           (make-instance 'sum-expression
+                          :left left
+                          :right right)))
+        (t
+         (error "Unable to parse expression: ~A" lisp-expr))))
+
 (defun parse (source)
-  (labels ((parse-expr (lisp-expr)
-             (cond ((integerp lisp-expr)
-                    (make-instance 'int-literal :value lisp-expr))
-                   ((and (listp lisp-expr) (eq '+ (first lisp-expr)))
-                    (let* ((left (parse-expr (second lisp-expr)))
-                           (right (parse-expr (third lisp-expr))))
-                      (make-instance 'sum-expression
-                                     :left left
-                                     :right right)))
-                   (t
-                    (error "Unable to parse expression: ~A" lisp-expr)))))
-    (let ((*package* (find-package "SBCL-LIBRARIAN-EXAMPLE")))
-      (with-input-from-string (stream source)
-        (parse-expr (read stream))))))
+  (with-input-from-string (stream source)
+    (parse-expr (read stream))))
 
 (defparameter *print-expression-indent* 0)
 

example/script.lisp

@@ -1,8 +1,13 @@
 (require '#:asdf)
 
+;; Requirement for loading the .asd directly can be avoided by adding
+;;
+;; sbcl-librarian/example/libcalc.asd
+;;
+;; to the system-index.txt file.
+(asdf:load-asd (truename "./libcalc.asd"))
 (asdf:load-system '#:libcalc)
 
-
 (in-package #:sbcl-librarian/example/libcalc)
 
 (build-bindings libcalc ".")