Documentation/extending: some improvements.

[lilypond.git] / Documentation / extending / programming-interface.itely

diff --git a/Documentation/extending/programming-interface.itely b/Documentation/extending/programming-interface.itely
index c5a1111a5a0d91436580911075e415f24b4f6a48..a816e564cf5c130973c4ec916233434efd7faf5d 100644 (file)
--- a/Documentation/extending/programming-interface.itely
+++ b/Documentation/extending/programming-interface.itely
@@ -207,16 +207,16 @@ functions (@pxref{Void scheme functions}) otherwise.
 @funindex \void
 
 Sometimes a procedure is executed in order to perform an action rather
-than return a value.  Some programming languages (like C and Scheme)
-use functions for either concept and just discard the returned value
+than return a value.  Some programming languages (like C and Scheme) use
+functions for either concept and just discard the returned value
 (usually by allowing any expression to act as statement, ignoring the
 result).  This is clever but error-prone: most C compilers nowadays
 offer warnings for various non-``void'' expressions being discarded.
-For many functions executing an action, the Scheme standards declare
-the return value to be unspecified.  Lilypond's Scheme interpreter
-Guile has a unique ``unspecified'' value that it usually (such when
-using @code{set!} directly on a variable) but unfortunately not
-consistently returns in such cases.
+For many functions executing an action, the Scheme standards declare the
+return value to be unspecified.  Lilypond's Scheme interpreter Guile has
+a unique value @code{*unspecified*} that it usually (such when using
+@code{set!} directly on a variable) but unfortunately not consistently
+returns in such cases.
 
 Defining a Lilypond function with @code{define-void-function} makes
 sure that this special value (the only value satisfying the predicate