Help/Language/Syntax-Shortcuts.html

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  27 <p class="p1"><b>Syntax Shortcuts</b></p>
  28 <p class="p2"><br></p>
  29 <p class="p3">This file shows a number of syntax equivalences in the compiler.</p>
  30 <p class="p2"><br></p>
  31 <p class="p4">__________________________________________________________________________</p>
  32 <p class="p5"><br></p>
  33 <p class="p6"><b>Example: multiple ways to write the same thing.</b></p>
  34 <p class="p7"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></b></p>
  35 <p class="p3">Because of the multiple syntax equivalences, some expressions can be written in many different ways. All of the following do the same thing and compile to the same code.<span class="Apple-converted-space"> </span></p>
  36 <p class="p5"><br></p>
  37 <p class="p8">// new argument syntax</p>
  38 <p class="p5"><br></p>
  39 <p class="p4">(1..10).collect({<span class="s1">|n|</span> n.squared }); <span class="s2">// receiver syntax</span></p>
  40 <p class="p5"><br></p>
  41 <p class="p4">collect((1..10), {<span class="s1">|n|</span> n.squared }); <span class="s2">// function call syntax</span></p>
  42 <p class="p5"><br></p>
  43 <p class="p8"><span class="s3">(1..10).collect {</span><span class="s1">|n|</span><span class="s3"> n.squared }; </span>// receiver syntax with trailing function arg</p>
  44 <p class="p5"><br></p>
  45 <p class="p8"><span class="s3">collect ((1..10)) {</span><span class="s1">|n|</span><span class="s3"> n.squared }; </span>// function call syntax with trailing function arg</p>
  46 <p class="p5"><br></p>
  47 <p class="p4">(1..10) collect: {<span class="s1">|n|</span> n.squared }; <span class="s2">// binary operator syntax</span></p>
  48 <p class="p5"><br></p>
  49 <p class="p5"><br></p>
  50 <p class="p8">// old argument syntax</p>
  51 <p class="p5"><br></p>
  52 <p class="p4">(1..10).collect({ <span class="s1">arg</span> n; n.squared }); <span class="s2">// receiver syntax</span></p>
  53 <p class="p5"><br></p>
  54 <p class="p4">collect((1..10), { <span class="s1">arg</span> n; n.squared }); <span class="s2">// function call syntax</span></p>
  55 <p class="p5"><br></p>
  56 <p class="p8"><span class="s3">(1..10).collect { </span><span class="s1">arg</span><span class="s3"> n; n.squared }; </span>// receiver syntax with trailing function arg</p>
  57 <p class="p5"><br></p>
  58 <p class="p8"><span class="s3">collect ((1..10)) { </span><span class="s1">arg</span><span class="s3"> n; n.squared }; </span>// function call syntax with trailing function arg</p>
  59 <p class="p5"><br></p>
  60 <p class="p4">(1..10) collect: { <span class="s1">arg</span> n; n.squared }; <span class="s2">// binary operator syntax</span></p>
  61 <p class="p5"><br></p>
  62 <p class="p5"><br></p>
  63 <p class="p8">// partial application syntax</p>
  64 <p class="p5"><br></p>
  65 <p class="p4">(1..10).collect( _.squared ); <span class="s2">// receiver syntax</span></p>
  66 <p class="p5"><br></p>
  67 <p class="p4">collect((1..10), _.squared ); <span class="s2">// function call syntax</span></p>
  68 <p class="p5"><br></p>
  69 <p class="p4">(1..10) collect: _.squared ; <span class="s2">// binary operator syntax</span></p>
  70 <p class="p5"><br></p>
  71 <p class="p5"><br></p>
  72 <p class="p3">You could even start expanding out the equivalent of <span class="s4">(1..10)</span> which is really a shortcut for <span class="s4">series(1, nil, 10)</span>. This could also be written <span class="s4">1.series(nil,10)</span>. This adds another 26 variations to the 13 variations above.</p>
  73 <p class="p2"><br></p>
  74 <p class="p4">__________________________________________________________________________</p>
  75 <p class="p2"><br></p>
  76 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>functional and receiver notation</b></p>
  77 <p class="p2"><br></p>
  78 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
  79 <p class="p2"><br></p>
  80 <p class="p4">f(x, y)<span class="Apple-tab-span">      </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>x.f(y)</p>
  81 <p class="p4">f(g(x))<span class="Apple-tab-span">      </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>x.g.f</p>
  82 <p class="p5"><br></p>
  83 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>defining instance variable accessor methods</b></p>
  84 <p class="p2"><br></p>
  85 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
  86 <p class="p2"><span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><b><span class="Apple-tab-span"> </span></b></p>
  87 <p class="p4">Thing { var x;<span class="Apple-converted-space">  <span class="Apple-tab-span">        </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></span>Thing { var &lt;&gt;x; }<span class="s5"><b><span class="Apple-tab-span"> </span></b></span></p>
  88 <p class="p4"><span class="Apple-tab-span">     </span>x { ^x } <span class="Apple-converted-space"> </span></p>
  89 <p class="p4"><span class="Apple-tab-span">     </span>x_ { arg z; x = z; }<span class="Apple-converted-space"> </span></p>
  90 <p class="p4">}<span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></p>
  91 <p class="p2"><br></p>
  92 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>calling an instance variable setter method</b></p>
  93 <p class="p2"><br></p>
  94 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
  95 <p class="p2"><br></p>
  96 <p class="p4">p.x_(y)<span class="Apple-tab-span">      </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>p.x = y;<span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></p>
  97 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>use a selector as binary operator</b></p>
  98 <p class="p5"><br></p>
  99 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 100 <p class="p2"><br></p>
 101 <p class="p4">min(x, y)<span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>x min: y</p>
 102 <p class="p5"><br></p>
 103 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>multiple assignment</b></p>
 104 <p class="p5"><br></p>
 105 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 106 <p class="p2"><br></p>
 107 <p class="p4">x = z.at(0); y = z.at(1);<span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span># x, y = z;</p>
 108 <p class="p5"><br></p>
 109 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>get environment variable</b></p>
 110 <p class="p5"><br></p>
 111 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 112 <p class="p2"><br></p>
 113 <p class="p4">'myName'.envirGet<span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>~myName</p>
 114 <p class="p5"><br></p>
 115 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>set environment variable</b></p>
 116 <p class="p5"><br></p>
 117 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 118 <p class="p2"><br></p>
 119 <p class="p4">'myName'.envirSet(9);<span class="Apple-tab-span">        </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>~myName = 9;</p>
 120 <p class="p5"><br></p>
 121 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>instantiate object</b></p>
 122 <p class="p5"><br></p>
 123 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 124 <p class="p2"><br></p>
 125 <p class="p4">Point.new(3, 4);<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>Point(3, 4)</p>
 126 <p class="p5"><br></p>
 127 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>create a collection</b></p>
 128 <p class="p5"><br></p>
 129 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 130 <p class="p2"><br></p>
 131 <p class="p4">Set.new.add(3).add(4).add(5);<span class="Apple-tab-span">        </span><span class="Apple-tab-span">    </span>Set[3, 4, 5]</p>
 132 <p class="p5"><br></p>
 133 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>moving blocks out of argument lists</b></p>
 134 <p class="p5"><br></p>
 135 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 136 <p class="p2"><br></p>
 137 <p class="p4">if (x&lt;3, {\abc}, {\def});<span class="Apple-tab-span"> </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>if (x&lt;3) {\abc} {\def}</p>
 138 <p class="p5"><br></p>
 139 <p class="p4">z.do({|x| x.play });<span class="Apple-tab-span"> </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>z.do {|x| x.play };</p>
 140 <p class="p5"><br></p>
 141 <p class="p4">while({ a &lt; b },{ a = a * 2 });<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span>while { a &lt; b } { a = a * 2 };</p>
 142 <p class="p5"><br></p>
 143 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>shorter argument lists</b></p>
 144 <p class="p5"><br></p>
 145 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 146 <p class="p2"><br></p>
 147 <p class="p4">{ arg x; x &lt; 2 }<span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>{|x| x &lt; 2 }</p>
 148 <p class="p5"><br></p>
 149 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>shorthand for Symbols</b></p>
 150 <p class="p5"><br></p>
 151 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 152 <p class="p2"><br></p>
 153 <p class="p4">'mySymbol'<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>\mySymbol</p>
 154 <p class="p5"><br></p>
 155 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>creating a Ref</b></p>
 156 <p class="p5"><br></p>
 157 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 158 <p class="p2"><br></p>
 159 <p class="p4">Ref.new(thing)<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>`thing</p>
 160 <p class="p5"><br></p>
 161 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>calling the 'value' method</b></p>
 162 <p class="p5"><br></p>
 163 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 164 <p class="p2"><br></p>
 165 <p class="p4">f.value(x)<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>f.(x)</p>
 166 <p class="p5"><br></p>
 167 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>indexing with 'at'</b></p>
 168 <p class="p5"><br></p>
 169 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 170 <p class="p2"><br></p>
 171 <p class="p4">z.at(i)<span class="Apple-tab-span">      </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>z[i]</p>
 172 <p class="p5"><br></p>
 173 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>indexing with 'put'</b></p>
 174 <p class="p5"><br></p>
 175 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 176 <p class="p2"><br></p>
 177 <p class="p4">z.put(i, y);<span class="Apple-tab-span"> </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>z[i] = y;</p>
 178 <p class="p5"><br></p>
 179 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>creating IdentityDictionaries</b></p>
 180 <p class="p5"><br></p>
 181 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 182 <p class="p2"><br></p>
 183 <p class="p4">IdentityDictionary['a'-&gt;1,'b'-&gt;2]<span class="Apple-tab-span">      </span><span class="Apple-tab-span">    </span>(a: 1, b: 2)</p>
 184 <p class="p5"><br></p>
 185 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>creating arithmetic series</b></p>
 186 <p class="p5"><br></p>
 187 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 188 <p class="p2"><br></p>
 189 <p class="p4">Array.series(16,1,1)<span class="s5"><i>, or<span class="Apple-converted-space">  </span></i></span>series(1,nil,16)<span class="Apple-tab-span">        </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>(1..16)</p>
 190 <p class="p5"><br></p>
 191 <p class="p4">Array.series(6,1,2)<span class="s5"><i>, or<span class="Apple-converted-space">  </span></i></span>series(1,3,11)<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>(1,3..11)</p>
 192 <p class="p5"><br></p>
 193 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>accessing subranges of Arrays</b></p>
 194 <p class="p5"><br></p>
 195 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 196 <p class="p2"><br></p>
 197 <p class="p4">a.copyRange(4,8)<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>a[4..8]</p>
 198 <p class="p5"><br></p>
 199 <p class="p4">a.copyToEnd(4)<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>a[4..]</p>
 200 <p class="p5"><br></p>
 201 <p class="p4">a.copyFromStart(4)<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>a[..4]</p>
 202 <p class="p5"><br></p>
 203 <p class="p5"><br></p>
 204 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>calling performList</b></p>
 205 <p class="p5"><br></p>
 206 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 207 <p class="p2"><br></p>
 208 <p class="p4">object.performList(\method, a, b, array)<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span>object.method(a, b, *array)</p>
 209 <p class="p5"><br></p>
 210 <p class="p5"><br></p>
 211 <p class="p6"><b><span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>partial application</b></p>
 212 <p class="p5"><br></p>
 213 <p class="p3"><b>instead of writing:<span class="Apple-tab-span">       </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>you can write:</b></p>
 214 <p class="p2"><br></p>
 215 <p class="p4">{|x| object.msg(a, x, b) }<span class="Apple-tab-span">   </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>object.msg(a, _, b)</p>
 216 <p class="p5"><br></p>
 217 <p class="p4">{|x,y| object.msg(a, x, y) }<span class="Apple-tab-span"> </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>object.msg(a, _, _)</p>
 218 <p class="p5"><br></p>
 219 <p class="p4">{|x| a + x }<span class="Apple-tab-span"> </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>a + _</p>
 220 <p class="p5"><br></p>
 221 <p class="p4">{|x| [a, b, x] }<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>[a, b, _]</p>
 222 <p class="p5"><br></p>
 223 <p class="p4">{|x| (a: x) }<span class="Apple-tab-span">        </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>(a: _)</p>
 224 <p class="p5"><br></p>
 225 <p class="p5"><br></p>
 226 <p class="p5"><br></p>
 227 <p class="p4">__________________________________________________________________________</p>
 228 </body>
 229 </html>