4447

1 files changed, 33 insertions, 33 deletions

diff --git a/html/chessboard.mu.html b/html/chessboard.mu.html
index 2efbb576..0cb1c0bb 100644
--- a/html/chessboard.mu.html
+++ b/html/chessboard.mu.html
@@ -15,8 +15,8 @@ body { font-size: 12pt; font-family: monospace; color: #aaaaaa; background-color
 a { color:#eeeeee; text-decoration: none; }
 a:hover { text-decoration: underline; }
 * { font-size: 12pt; font-size: 1em; }
+.muData { color: #ffff00; }
 .muRecipe { color: #ff8700; }
-.muScenario { color: #00af00; }
 .Special { color: #c00000; }
 .Delimiter { color: #800080; }
 .SalientComment { color: #00ffff; }
@@ -24,9 +24,9 @@ a:hover { text-decoration: underline; }
 .Comment a { color:#0000ee; text-decoration:underline; }
 .Constant { color: #00a0a0; }
 .LineNr { color: #444444; }
-.CommentedCode { color: #6c6c6c; }
 .muControl { color: #c0a020; }
-.muData { color: #ffff00; }
+.CommentedCode { color: #6c6c6c; }
+.muScenario { color: #00af00; }
 -->
 </style>
 
@@ -67,16 +67,16 @@ if ('onhashchange' in window) {
 <span id="L4" class="LineNr">  4 </span><span class="muRecipe">def</span> <a href='chessboard.mu.html#L4'>main</a> [
 <span id="L5" class="LineNr">  5 </span>  <span class="Constant">local-scope</span>
 <span id="L6" class="LineNr">  6 </span>  open-console  <span class="Comment"># take control of screen, keyboard and mouse</span>
-<span id="L7" class="LineNr">  7 </span>  <a href='081print.mu.html#L46'>clear-screen</a> <span class="Constant">0/screen</span>  <span class="Comment"># non-scrolling app</span>
+<span id="L7" class="LineNr">  7 </span>  <a href='081print.mu.html#L46'>clear-screen</a><span class="Constant"> null/screen</span>  <span class="Comment"># non-scrolling app</span>
 <span id="L8" class="LineNr">  8 </span>
 <span id="L9" class="LineNr">  9 </span>  <span class="Comment"># The chessboard function takes keyboard and screen objects as inputs.</span>
 <span id="L10" class="LineNr"> 10 </span>  <span class="Comment">#</span>
 <span id="L11" class="LineNr"> 11 </span>  <span class="Comment"># In Mu it is good form (though not required) to explicitly state what</span>
 <span id="L12" class="LineNr"> 12 </span>  <span class="Comment"># hardware a function needs.</span>
 <span id="L13" class="LineNr"> 13 </span>  <span class="Comment">#</span>
-<span id="L14" class="LineNr"> 14 </span>  <span class="Comment"># Here the console and screen are both 0, which usually indicates real</span>
+<span id="L14" class="LineNr"> 14 </span>  <span class="Comment"># Here the console and screen are both null, which usually indicates real</span>
 <span id="L15" class="LineNr"> 15 </span>  <span class="Comment"># hardware rather than a fake for testing as you'll see below.</span>
-<span id="L16" class="LineNr"> 16 </span>  <a href='chessboard.mu.html#L69'>chessboard</a> <span class="Constant">0/screen</span>, <span class="Constant">0/console</span>
+<span id="L16" class="LineNr"> 16 </span>  <a href='chessboard.mu.html#L69'>chessboard</a><span class="Constant"> null/screen, null/console</span>
 <span id="L17" class="LineNr"> 17 </span>
 <span id="L18" class="LineNr"> 18 </span>  close-console  <span class="Comment"># clean up screen, keyboard and mouse</span>
 <span id="L19" class="LineNr"> 19 </span>]
@@ -312,27 +312,27 @@ if ('onhashchange' in window) {
 <span id="L249" class="LineNr">249 </span>  <span class="Constant">local-scope</span>
 <span id="L250" class="LineNr">250 </span>  <span class="Constant">load-inputs</span>
 <span id="L251" class="LineNr">251 </span>  from-file:num, quit?:bool, error?:bool <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L276'>read-file</a> stdin, <a href='081print.mu.html#L16'>screen</a>
-<span id="L252" class="LineNr">252 </span>  <span class="muControl">return-if</span> quit?, <span class="Constant">0/dummy</span>
-<span id="L253" class="LineNr">253 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>
+<span id="L252" class="LineNr">252 </span>  <span class="muControl">return-if</span> quit?,<span class="Constant"> null/dummy</span>
+<span id="L253" class="LineNr">253 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy</span>
 <span id="L254" class="LineNr">254 </span>  <span class="Comment"># construct the move object</span>
 <span id="L255" class="LineNr">255 </span>  result:&amp;:<a href='chessboard.mu.html#L239'>move</a> <span class="Special">&lt;-</span> new <span class="Constant"><a href='chessboard.mu.html#L239'>move</a>:type</span>
 <span id="L256" class="LineNr">256 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">from-file:offset</span>, from-file
 <span id="L257" class="LineNr">257 </span>  from-rank:num, quit?, error? <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L314'>read-rank</a> stdin, <a href='081print.mu.html#L16'>screen</a>
-<span id="L258" class="LineNr">258 </span>  <span class="muControl">return-if</span> quit?, <span class="Constant">0/dummy</span>
-<span id="L259" class="LineNr">259 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>
+<span id="L258" class="LineNr">258 </span>  <span class="muControl">return-if</span> quit?,<span class="Constant"> null/dummy</span>
+<span id="L259" class="LineNr">259 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy</span>
 <span id="L260" class="LineNr">260 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">from-rank:offset</span>, from-rank
 <span id="L261" class="LineNr">261 </span>  error? <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L352'>expect-from-channel</a> stdin, <span class="Constant">45/dash</span>, <a href='081print.mu.html#L16'>screen</a>
-<span id="L262" class="LineNr">262 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>
+<span id="L262" class="LineNr">262 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy, false/quit</span>
 <span id="L263" class="LineNr">263 </span>  to-file:num, quit?, error? <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L276'>read-file</a> stdin, <a href='081print.mu.html#L16'>screen</a>
-<span id="L264" class="LineNr">264 </span>  <span class="muControl">return-if</span> quit?, <span class="Constant">0/dummy</span>
-<span id="L265" class="LineNr">265 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>
+<span id="L264" class="LineNr">264 </span>  <span class="muControl">return-if</span> quit?,<span class="Constant"> null/dummy</span>
+<span id="L265" class="LineNr">265 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy</span>
 <span id="L266" class="LineNr">266 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">to-file:offset</span>, to-file
 <span id="L267" class="LineNr">267 </span>  to-rank:num, quit?, error? <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L314'>read-rank</a> stdin, <a href='081print.mu.html#L16'>screen</a>
-<span id="L268" class="LineNr">268 </span>  <span class="muControl">return-if</span> quit?, <span class="Constant">0/dummy</span>
-<span id="L269" class="LineNr">269 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>
+<span id="L268" class="LineNr">268 </span>  <span class="muControl">return-if</span> quit?,<span class="Constant"> null/dummy</span>
+<span id="L269" class="LineNr">269 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy</span>
 <span id="L270" class="LineNr">270 </span>  *result <span class="Special">&lt;-</span> put *result, <span class="Constant">to-rank:offset</span>, to-rank
 <span id="L271" class="LineNr">271 </span>  error? <span class="Special">&lt;-</span> <a href='chessboard.mu.html#L352'>expect-from-channel</a> stdin, <span class="Constant">10/newline</span>, <a href='081print.mu.html#L16'>screen</a>
-<span id="L272" class="LineNr">272 </span>  <span class="muControl">return-if</span> error?, <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>
+<span id="L272" class="LineNr">272 </span>  <span class="muControl">return-if</span> error?,<span class="Constant"> null/dummy, false/quit</span>
 <span id="L273" class="LineNr">273 </span>]
 <span id="L274" class="LineNr">274 </span>
 <span id="L275" class="LineNr">275 </span><span class="Comment"># valid values for file: 0-7</span>
@@ -340,18 +340,18 @@ if ('onhashchange' in window) {
 <span id="L277" class="LineNr">277 </span>  <span class="Constant">local-scope</span>
 <span id="L278" class="LineNr">278 </span>  <span class="Constant">load-inputs</span>
 <span id="L279" class="LineNr">279 </span>  c:char, eof?:bool, stdin <span class="Special">&lt;-</span> read stdin
-<span id="L280" class="LineNr">280 </span>  <span class="muControl">return-if</span> eof?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L280" class="LineNr">280 </span>  <span class="muControl">return-if</span> eof?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L281" class="LineNr">281 </span>  q-pressed?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">81/Q</span>
-<span id="L282" class="LineNr">282 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L282" class="LineNr">282 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L283" class="LineNr">283 </span>  q-pressed? <span class="Special">&lt;-</span> equal c, <span class="Constant">113/q</span>
-<span id="L284" class="LineNr">284 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L284" class="LineNr">284 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L285" class="LineNr">285 </span>  empty-fake-keyboard?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">0/eof</span>
-<span id="L286" class="LineNr">286 </span>  <span class="muControl">return-if</span> empty-fake-keyboard?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L286" class="LineNr">286 </span>  <span class="muControl">return-if</span> empty-fake-keyboard?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L287" class="LineNr">287 </span>  <span class="Delimiter">{</span>
 <span id="L288" class="LineNr">288 </span>    newline?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">10/newline</span>
 <span id="L289" class="LineNr">289 </span>    <span class="muControl">break-unless</span> newline?
 <span id="L290" class="LineNr">290 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[that's not enough]</span>
-<span id="L291" class="LineNr">291 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L291" class="LineNr">291 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quit, true/error</span>
 <span id="L292" class="LineNr">292 </span>  <span class="Delimiter">}</span>
 <span id="L293" class="LineNr">293 </span>  file:num <span class="Special">&lt;-</span> subtract c, <span class="Constant">97/a</span>
 <span id="L294" class="LineNr">294 </span>  <span class="Comment"># 'a' &lt;= file &lt;= 'h'</span>
@@ -361,16 +361,16 @@ if ('onhashchange' in window) {
 <span id="L298" class="LineNr">298 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[file too low: ]</span>
 <span id="L299" class="LineNr">299 </span>    print <a href='081print.mu.html#L16'>screen</a>, c
 <span id="L300" class="LineNr">300 </span>    <a href='081print.mu.html#L752'>cursor-to-next-line</a> <a href='081print.mu.html#L16'>screen</a>
-<span id="L301" class="LineNr">301 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L301" class="LineNr">301 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quit, true/error</span>
 <span id="L302" class="LineNr">302 </span>  <span class="Delimiter">}</span>
 <span id="L303" class="LineNr">303 </span>  <span class="Delimiter">{</span>
 <span id="L304" class="LineNr">304 </span>    below-max:bool <span class="Special">&lt;-</span> lesser-than file,<span class="Constant"> 8</span>
 <span id="L305" class="LineNr">305 </span>    <span class="muControl">break-if</span> below-max
 <span id="L306" class="LineNr">306 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[file too high: ]</span>
 <span id="L307" class="LineNr">307 </span>    print <a href='081print.mu.html#L16'>screen</a>, c
-<span id="L308" class="LineNr">308 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L308" class="LineNr">308 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quit, true/error</span>
 <span id="L309" class="LineNr">309 </span>  <span class="Delimiter">}</span>
-<span id="L310" class="LineNr">310 </span> <span class="muControl"> return</span> file, <span class="Constant">0/quit</span>, <span class="Constant">0/error</span>
+<span id="L310" class="LineNr">310 </span> <span class="muControl"> return</span> file,<span class="Constant"> false/don't-quit, false/no-error</span>
 <span id="L311" class="LineNr">311 </span>]
 <span id="L312" class="LineNr">312 </span>
 <span id="L313" class="LineNr">313 </span><span class="Comment"># valid values for rank: 0-7</span>
@@ -378,18 +378,18 @@ if ('onhashchange' in window) {
 <span id="L315" class="LineNr">315 </span>  <span class="Constant">local-scope</span>
 <span id="L316" class="LineNr">316 </span>  <span class="Constant">load-inputs</span>
 <span id="L317" class="LineNr">317 </span>  c:char, eof?:bool, stdin <span class="Special">&lt;-</span> read stdin
-<span id="L318" class="LineNr">318 </span>  <span class="muControl">return-if</span> eof?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L318" class="LineNr">318 </span>  <span class="muControl">return-if</span> eof?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L319" class="LineNr">319 </span>  q-pressed?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">81/Q</span>
-<span id="L320" class="LineNr">320 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L320" class="LineNr">320 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L321" class="LineNr">321 </span>  q-pressed? <span class="Special">&lt;-</span> equal c, <span class="Constant">113/q</span>
-<span id="L322" class="LineNr">322 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L322" class="LineNr">322 </span>  <span class="muControl">return-if</span> q-pressed?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L323" class="LineNr">323 </span>  empty-fake-keyboard?:bool <span class="Special">&lt;-</span> equal c, <span class="Constant">0/eof</span>
-<span id="L324" class="LineNr">324 </span>  <span class="muControl">return-if</span> empty-fake-keyboard?, <span class="Constant">0/dummy</span>, <span class="Constant">1/quit</span>, <span class="Constant">0/error</span>
+<span id="L324" class="LineNr">324 </span>  <span class="muControl">return-if</span> empty-fake-keyboard?, <span class="Constant">0/dummy</span>,<span class="Constant"> true/quit, false/no-error</span>
 <span id="L325" class="LineNr">325 </span>  <span class="Delimiter">{</span>
 <span id="L326" class="LineNr">326 </span>    newline?:bool <span class="Special">&lt;-</span> equal c,<span class="Constant"> 10</span>  <span class="Comment"># newline</span>
 <span id="L327" class="LineNr">327 </span>    <span class="muControl">break-unless</span> newline?
 <span id="L328" class="LineNr">328 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[that's not enough]</span>
-<span id="L329" class="LineNr">329 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L329" class="LineNr">329 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quite, true/error</span>
 <span id="L330" class="LineNr">330 </span>  <span class="Delimiter">}</span>
 <span id="L331" class="LineNr">331 </span>  rank:num <span class="Special">&lt;-</span> subtract c, <span class="Constant">49/'1'</span>
 <span id="L332" class="LineNr">332 </span>  <span class="Comment"># assert'1' &lt;= rank &lt;= '8'</span>
@@ -398,16 +398,16 @@ if ('onhashchange' in window) {
 <span id="L335" class="LineNr">335 </span>    <span class="muControl">break-if</span> above-min
 <span id="L336" class="LineNr">336 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[rank too low: ]</span>
 <span id="L337" class="LineNr">337 </span>    print <a href='081print.mu.html#L16'>screen</a>, c
-<span id="L338" class="LineNr">338 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L338" class="LineNr">338 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quite, true/error</span>
 <span id="L339" class="LineNr">339 </span>  <span class="Delimiter">}</span>
 <span id="L340" class="LineNr">340 </span>  <span class="Delimiter">{</span>
 <span id="L341" class="LineNr">341 </span>    below-max:bool <span class="Special">&lt;-</span> lesser-or-equal rank,<span class="Constant"> 7</span>
 <span id="L342" class="LineNr">342 </span>    <span class="muControl">break-if</span> below-max
 <span id="L343" class="LineNr">343 </span>    print <a href='081print.mu.html#L16'>screen</a>, <span class="Constant">[rank too high: ]</span>
 <span id="L344" class="LineNr">344 </span>    print <a href='081print.mu.html#L16'>screen</a>, c
-<span id="L345" class="LineNr">345 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>, <span class="Constant">0/quit</span>, <span class="Constant">1/error</span>
+<span id="L345" class="LineNr">345 </span>   <span class="muControl"> return</span> <span class="Constant">0/dummy</span>,<span class="Constant"> false/don't-quite, true/error</span>
 <span id="L346" class="LineNr">346 </span>  <span class="Delimiter">}</span>
-<span id="L347" class="LineNr">347 </span> <span class="muControl"> return</span> rank, <span class="Constant">0/quit</span>, <span class="Constant">0/error</span>
+<span id="L347" class="LineNr">347 </span> <span class="muControl"> return</span> rank,<span class="Constant"> false/don't-quite, false/no-error</span>
 <span id="L348" class="LineNr">348 </span>]
 <span id="L349" class="LineNr">349 </span>
 <span id="L350" class="LineNr">350 </span><span class="Comment"># read a character from the given channel and check that it's what we expect</span>
@@ -416,7 +416,7 @@ if ('onhashchange' in window) {
 <span id="L353" class="LineNr">353 </span>  <span class="Constant">local-scope</span>
 <span id="L354" class="LineNr">354 </span>  <span class="Constant">load-inputs</span>
 <span id="L355" class="LineNr">355 </span>  c:char, eof?:bool, stdin <span class="Special">&lt;-</span> read stdin
-<span id="L356" class="LineNr">356 </span>  <span class="muControl">return-if</span> eof? <span class="Constant">1/true</span>
+<span id="L356" class="LineNr">356 </span>  <span class="muControl">return-if</span> eof?<span class="Constant"> true</span>
 <span id="L357" class="LineNr">357 </span>  <span class="Delimiter">{</span>
 <span id="L358" class="LineNr">358 </span>    match?:bool <span class="Special">&lt;-</span> equal c, expected
 <span id="L359" class="LineNr">359 </span>    <span class="muControl">break-if</span> match?