faq for unused variable

Author: bksaiki

src/syntax/read.rkt

@@ -113,13 +113,15 @@
   (unless (set=? vars used)
     (define unused (set-subtract vars used))
     (warn 'unused-variable
+          #:url "faq.html#unused-variable"
           "unused ~a ~a" (if (equal? (set-count unused) 1) "variable" "variables")
           (string-join (map ~a unused) ", "))))
 
 (define (check-weird-variables vars)
   (for* ([var vars] [const (all-constants)])
     (when (string-ci=? (symbol->string var) (symbol->string const))
       (warn 'strange-variable
+            #:url "faq.html#strange-variable"
             "unusual variable ~a; did you mean ~a?" var const))))
 
 (define (our-read-syntax port name)

www/doc/1.6/faq.html

@@ -111,6 +111,19 @@ <h3 id="unsound-rules">Unsound rule application detected</h3>
     failed to simplify the output.
   </p>
 
+  <h3 id="unused-variable">Unused variable <var>var</var></h3>
+  
+  <p>
+    The input FPCore contains a variable that is not
+      used in the body expression.
+  </p>
+
+  <h3 id="strange-variable">Strange variable <var>var</var></h3>
+  
+  <p>
+    The input expression contains a variable that is similar in name
+      to named constants, e.g. <var>e</var> instead of <var>E</var>.
+  </p>
 
   <h2>Known bugs</h2>