100 lines
2.4 KiB
HTML
100 lines
2.4 KiB
HTML
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<h2>Comments</h2>
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<pre><code>// Single line comment
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/* Mutli-line
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comment */</code></pre>
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<h2>Strings and characters</h2>
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<pre><code>'a'
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"foo bar baz"
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"""Multi-line
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string"""</code></pre>
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<h2>Numbers</h2>
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<pre><code>0
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21
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0xFFFFFFFF
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-42L
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0.0
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1e30f
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3.14159f
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1.0e-100
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.1
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</code></pre>
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<h2>Symbols</h2>
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<pre><code>'x
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'identifier</code></pre>
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<h2>Full example</h2>
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<pre><code>// Contributed by John Williams
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package examples
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object lazyLib {
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/** Delay the evaluation of an expression until it is needed. */
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def delay[A](value: => A): Susp[A] = new SuspImpl[A](value)
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/** Get the value of a delayed expression. */
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implicit def force[A](s: Susp[A]): A = s()
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/**
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* Data type of suspended computations. (The name froms from ML.)
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*/
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abstract class Susp[+A] extends Function0[A]
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/**
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* Implementation of suspended computations, separated from the
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* abstract class so that the type parameter can be invariant.
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*/
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class SuspImpl[A](lazyValue: => A) extends Susp[A] {
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private var maybeValue: Option[A] = None
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override def apply() = maybeValue match {
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case None =>
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val value = lazyValue
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maybeValue = Some(value)
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value
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case Some(value) =>
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value
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}
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override def toString() = maybeValue match {
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case None => "Susp(?)"
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case Some(value) => "Susp(" + value + ")"
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}
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}
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}
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object lazyEvaluation {
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import lazyLib._
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def main(args: Array[String]) = {
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val s: Susp[Int] = delay { println("evaluating..."); 3 }
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println("s = " + s) // show that s is unevaluated
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println("s() = " + s()) // evaluate s
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println("s = " + s) // show that the value is saved
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println("2 + s = " + (2 + s)) // implicit call to force()
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val sl = delay { Some(3) }
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val sl1: Susp[Some[Int]] = sl
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val sl2: Susp[Option[Int]] = sl1 // the type is covariant
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println("sl2 = " + sl2)
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println("sl2() = " + sl2())
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println("sl2 = " + sl2)
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}
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}</code></pre>
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<h2>Known failures</h2>
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<p>There are certain edge cases where Prism will fail.
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There are always such cases in every regex-based syntax highlighter.
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However, Prism dares to be open and honest about them.
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If a failure is listed here, it doesn’t mean it will never be fixed. This is more of a “known bugs” list, just with a certain type of bug.
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</p>
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<h3>Nested block comments</h3>
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<pre><code>/* Nested block
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/* comments
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are */
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not supported */</code></pre>
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