turtlestitch/libraries/iteration-composition.xml

<blocks app="Snap! 4.0, http://snap.berkeley.edu" version="1"><block-definition s="cascade %&apos;num&apos; times %&apos;function&apos; %&apos;init&apos; %&apos;#&apos;" type="reporter" category="control"><comment x="0" y="0" w="138" collapsed="false">Call f(f(f(...(f(x))))) n times where the three input slots are n, f, and x from left to right.  The # variable can be used inside f to represent how many times f has been called.</comment><header></header><code></code><inputs><input type="%n"></input><input type="%repRing"></input><input type="%s"></input><input type="%upvar"></input></inputs><script><block s="doDeclareVariables"><list><l>result</l></list></block><block s="doSetVar"><l>result</l><block var="init"/></block><block s="doSetVar"><l>#</l><l>0</l></block><block s="doRepeat"><block var="num"/><script><block s="doChangeVar"><l>#</l><l>1</l></block><block s="doSetVar"><l>result</l><block s="evaluate"><block var="function"/><list><block var="result"/></list></block></block></script></block><block s="doReport"><block var="result"/></block></script></block-definition><block-definition s="cascade until %&apos;pred&apos; %&apos;function&apos; %&apos;init&apos; %&apos;#&apos;" type="reporter" category="control"><comment x="0" y="0" w="90" collapsed="false">Call f(f(f(...(f(x))))) until condition is true, where the three input slots are condition, f, and x from left to right.  The # variable can be used inside f or condition to indicate how many times f has been called.</comment><header></header><code></code><inputs><input type="%predRing"></input><input type="%repRing"></input><input type="%s"></input><input type="%upvar"></input></inputs><script><block s="doDeclareVariables"><list><l>result</l></list></block><block s="doSetVar"><l>result</l><block var="init"/></block><block s="doSetVar"><l>#</l><l>0</l></block><block s="doUntil"><block s="evaluate"><block var="pred"/><list><block var="result"/></list></block><script><block s="doChangeVar"><l>#</l><l>1</l></block><block s="doSetVar"><l>result</l><block s="evaluate"><block var="function"/><list><block var="result"/></list></block></block></script></block><block s="doReport"><block var="result"/></block></script></block-definition><block-definition s="compose %&apos;f&apos; %&apos;g&apos;" type="reporter" category="control"><comment x="0" y="0" w="90" collapsed="false">Returns the function f(g(x)) where f and g are the two inputs.</comment><header></header><code></code><inputs><input type="%repRing"></input><input type="%repRing"></input></inputs><script><block s="doReport"><block s="reifyReporter"><autolambda><block s="evaluate"><block var="f"/><list><block s="evaluate"><block var="g"/><list><l></l></list></block></list></block></autolambda><list></list></block></block></script></block-definition><block-definition s="repeat %&apos;action&apos; until %&apos;pred&apos;" type="command" category="control"><comment x="0" y="0" w="90" collapsed="false">Like the built-in REPEAT UNTIL block, except that the ending condition is not tested until the script has been run the first time.  So the script is run at least once.</comment><header></header><code></code><inputs><input type="%cs"></input><input type="%boolUE"></input></inputs><script><block s="doRun"><block var="action"/><list></list></block><block s="doUntil"><block s="evaluate"><block var="pred"/><list></list></block><script><block s="doRun"><block var="action"/><list></list></block></script></block></script></block-definition><block-definition s="repeat %&apos;action&apos; while %&apos;pred&apos;" type="command" category="control"><comment x="0" y="0" w="90" collapsed="false">Run the script repeatedly, as long as the given condition is true.  Runs the script at least once before testing the condition.</comment><header></header><code></code><inputs><input type="%cs"></input><input type="%boolUE"></input></inputs><script><block s="doRun"><block var="action"/><list></list></block><block s="doUntil"><block s="reportNot"><block s="evaluate"><block var="pred"/><list></list></block></block><script><block s="doRun"><block var="act