Update typecheck library

- Add `unstable` suffix.
- Add portable R7RS implementation.
- Add tests.

live/typecheck/live.r7rs.scm

@@ -0,0 +1,11 @@
+(define-syntax typecheck-bytevector
+  (syntax-rules ()
+    ((_ who var)
+     (unless (bytevector? var)
+       (error "Not a bytevector" var 'who)))))
+
+(define-syntax typecheck-string
+  (syntax-rules ()
+    ((_ who var)
+     (unless (string? var)
+       (error "Not a string" var 'who)))))

live/typecheck/unstable.sld

@@ -0,0 +1,9 @@
+(define-library (live typecheck unstable)
+  (export typecheck-bytevector
+          typecheck-string)
+  (import (scheme base))
+  (cond-expand
+    (chicken
+     (include "live.chicken.scm"))
+    (else
+     (include "live.r7rs.scm"))))

tests/typecheck.scm

@@ -0,0 +1,21 @@
+(import (scheme base)
+        (live typecheck unstable)
+        (live test))
+
+(test-begin "live/typecheck")
+
+(test-group "typecheck-bytevector"
+  (let ((foo (bytevector)))
+    (test-assert (begin (typecheck-bytevector just-testing foo)
+                        #t)))
+  (let ((foo 123))
+    (test-error (typecheck-bytevector just-testing foo))))
+
+(test-group "typecheck-string"
+  (let ((foo (string)))
+    (test-assert (begin (typecheck-string just-testing foo)
+                        #t)))
+  (let ((foo 123))
+    (test-error (typecheck-string just-testing foo))))
+
+(test-end)