Doc: closure example
This commit is contained in:
+130
-16
@@ -1853,6 +1853,18 @@ If the left variable is NOT defined, the right expression is not evaluated at al
|
||||
<p><code>>>></code> <code class="blue">var</code><br>
|
||||
<code class="green">3</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <code class="blue">x ?! 5</code><br>
|
||||
<code class="green">nil</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <code class="blue">x=1; x ?! 5</code><br>
|
||||
<code class="green">5</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <code class="blue">y ?! (c=5); c</code><br>
|
||||
<code class="red">Eval Error: undefined variable or function "c"</code></p>
|
||||
</div>
|
||||
<div class="admonitionblock note">
|
||||
<table>
|
||||
<tr>
|
||||
@@ -1920,7 +1932,7 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>iterator</em> <code>++</code> → <em>any</em></p></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td class="tableblock halign-center valign-top" rowspan="2"><p class="tableblock"><strong>DEFAULT</strong></p></td>
|
||||
<td class="tableblock halign-center valign-top" rowspan="3"><p class="tableblock"><strong>DEFAULT</strong></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><code class="blue">??</code></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Infix</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Default value</em></p></td>
|
||||
@@ -1933,11 +1945,10 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>variable</em> <code>?=</code> <em>any-expr</em> → <em>any</em></p></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><strong>ITER</strong><sup>1</sup></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><code class="blue">()</code></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Prefix</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Iterator value</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><code>()</code> <em>iterator</em> → <em>any</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><code class="blue">?!</code></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Infix</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>Alternate value</em></p></td>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><em>variable</em> <code>?!</code> <em>any-expr</em> → <em>any</em></p></td>
|
||||
</tr>
|
||||
<tr>
|
||||
<td class="tableblock halign-center valign-top"><p class="tableblock"><strong>FACT</strong></p></td>
|
||||
@@ -2170,9 +2181,6 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
</tr>
|
||||
</tbody>
|
||||
</table>
|
||||
<div class="paragraph">
|
||||
<p><sup>1</sup> Experimental</p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect1">
|
||||
@@ -2194,23 +2202,51 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
<div class="sect2">
|
||||
<h3 id="_expr_function_definition"><a class="anchor" href="#_expr_function_definition"></a><a class="link" href="#_expr_function_definition">6.1. <em>Expr</em> function definition</a></h3>
|
||||
<div class="paragraph">
|
||||
<p>A function is identified and referenced by its name. It can have zero or more parameter. <em>Expr</em> functions also support optional parameters.</p>
|
||||
<p>A function is identified and referenced by its name. It can have zero or more parameter. <em>Expr</em> functions also support optional parameters and passing paramters by name.</p>
|
||||
</div>
|
||||
<div class="exampleblock">
|
||||
<div class="title">Example 14. Expr’s function definition syntax</div>
|
||||
<div class="content">
|
||||
<div class="paragraph">
|
||||
<p><strong><em>function-definition</em></strong> = <em>identifier</em> "<strong>=</strong>" "<strong>func(</strong>" [<em>param-list</em>] "<strong>)</strong>" "<strong>{</strong>" <em>multi-expression</em> "<strong>}</strong>"<br>
|
||||
<em>param_list</em> = <em>required-param-list</em> [ "<strong>,</strong>" <em>optional-param-list</em> ]<br>
|
||||
<p><strong><em>function-definition</em></strong> = <em>identifier</em> "<strong>=</strong>" "<strong>func(</strong>" [<em>formal-param-list</em>] "<strong>)</strong>" "<strong>{</strong>" <em>multi-expression</em> "<strong>}</strong>"<br>
|
||||
<em>formal-param_list</em> = <em>required-param-list</em> [ "<strong>,</strong>" <em>optional-param-list</em> ]<br>
|
||||
<em>required-param-list</em> = <em>identifier</em> { "<strong>,</strong>" <em>identifier</em> }<br>
|
||||
<em>optional-param-list</em> = <em>optional-parm</em> { "<strong>,</strong>" <em>optional-param</em> }<br>
|
||||
<em>optional-param</em> = <em>identifier</em> "<strong>=</strong>" <em>any-expr</em></p>
|
||||
<em>optional-param</em> = <em>param-name</em> "<strong>=</strong>" <em>any-expr</em><br>
|
||||
<em>param-name</em> = <em>identifier</em></p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples</div>
|
||||
<p><mark>TODO</mark></p>
|
||||
<p><code>>>></code> <em class="gray">// A simple function: it takes two parameters and returns their "sum"</em><strong><sup>(*)</sup></strong><br>
|
||||
<code>>>></code> <code class="blue">sum = func(a, b){ a + b }</code><br>
|
||||
<code class="green">sum(a, b):any{}</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><sup>(*)</sup> Since the plus, *+*, operator is defined for multiple data-types, the <em>sum()</em> function can be used for any pair of that types.</p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <em class="gray">// A more complex example: recursive calculation of the n-th value of Fibonacci’s sequence</em><br>
|
||||
<code>>>></code> <code class="blue">fib = func(n){ n ? [0] {0}: [1] {1} :: {fib(n-1)+fib(n-2)} }</code><br>
|
||||
<code class="green">fib(n):any{}</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <em class="gray">// Same function fib() but entered by splitting it over mulple text lines</em><br>
|
||||
<code>>>></code> <code class="blue">fib = func(n){ \</code><br>
|
||||
<code>...</code> <code class="blue">  n ? \</code><br>
|
||||
<code>...</code> <code class="blue">    [0] {0} : \</code><br>
|
||||
<code>...</code> <code class="blue">    [1] {1} :: \</code><br>
|
||||
<code>...</code> <code class="blue">    { \</code><br>
|
||||
<code>...</code> <code class="blue">      fib(n-1) + fib(n-2) \</code><br>
|
||||
<code>...</code> <code class="blue">    } \</code><br>
|
||||
<code>...</code> <code class="blue">}</code><br>
|
||||
<code class="green">fib(n):any{}</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p><code>>>></code> <em class="gray">// Required and optional parameters</em><br>
|
||||
<code>>>></code> <code class="blue">measure = func(value, unit="meter"){ value + " " + unit + (value > 1) ? [true] {"s"} :: {""}}</code><br>
|
||||
<code class="green">measure(value, unit="meter"):any{}</code></p>
|
||||
</div>
|
||||
</div>
|
||||
<div class="sect2">
|
||||
@@ -2222,7 +2258,85 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
<div class="sect2">
|
||||
<h3 id="_function_calls"><a class="anchor" href="#_function_calls"></a><a class="link" href="#_function_calls">6.3. Function calls</a></h3>
|
||||
<div class="paragraph">
|
||||
<p><mark>TODO: function calls operations</mark></p>
|
||||
<p>To call a function, either Expr or Golang type, it is necessary to specify its name and, at least, its required parameters.</p>
|
||||
</div>
|
||||
<div class="exampleblock">
|
||||
<div class="title">Example 15. Function invocation syntax</div>
|
||||
<div class="content">
|
||||
<div class="paragraph">
|
||||
<p><strong><em>function-call</em></strong> = <em>identifier</em> "<strong>(</strong>" <em>actual-param-list</em> "<strong>)</strong>"<br>
|
||||
<em>actual-param-list</em> = [<em>positional-params</em>] [<em>named-parameters</em>]<br>
|
||||
<em>positional-params</em> = <em>any-value</em> { "<strong>,</strong>" <em>any-value</em> }<br>
|
||||
<em>named-params</em> = <em>param-name</em> "<strong>=</strong>" <em>any-value</em> { "<strong>,</strong>" <em>param-name</em> "<strong>=</strong>" <em>any-value</em> }<br>
|
||||
<em>param-name</em> = <em>identifier</em></p>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples of calling the <code>sum()</code> functions defined above</div>
|
||||
<p><code>>>></code> <em class="gray">// sum of two integers</em><br>
|
||||
<code>>>></code> <code class="blue">sum(-6, 2)</code><br>
|
||||
<code class="green">-4</code><br>
|
||||
<code>>>></code> <em class="gray">// same as above but passing the parameters by name</em><br>
|
||||
<code>>>></code> <code class="blue">sum(a=-6, b=2)</code><br>
|
||||
<code class="green">-4</code><br>
|
||||
<code>>>></code> <em class="gray">// again, but swapping parameter positions (see the diff() examples below)</em><br>
|
||||
<code>>>></code> <code class="blue">sum(b=2, a=-6)</code><br>
|
||||
<code class="green">-4</code><br>
|
||||
<code>>>></code> <em class="gray">// sum of a fraction and an integer</em><br>
|
||||
<code>>>></code> <code class="blue">sum(3|2, 2)</code><br>
|
||||
<code class="green">7|2</code><br>
|
||||
<code>>>></code> <em class="gray">// sum of two strings</em><br>
|
||||
<code>>>></code> <code class="blue">sum("bye", "-bye")</code><br>
|
||||
<code class="green">"bye-bye"</code><br>
|
||||
<code>>>></code> <em class="gray">// sum of two lists</em><br>
|
||||
<code>>>></code> <code class="blue">sum(["one", 1], ["two", 2])</code><br>
|
||||
<code class="green">["one", 1, "two", 2]</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples of calling a function with parameters passed by name</div>
|
||||
<p><code>>>></code> <em class="gray">// diff(a,b) calculates a-b</em><br>
|
||||
<code>>>></code> <code class="blue">diff = func(a,b){a-b}</code><br>
|
||||
<code class="green">diff(a, b):any{}</code><br>
|
||||
<code>>>></code> <em class="gray">// simple invocation</em><br>
|
||||
<code>>>></code> <code class="blue">diff(10,8)</code><br>
|
||||
<code class="green">2</code><br>
|
||||
<code>>>></code> <em class="gray">// swapped parameters passed by name</em><br>
|
||||
<code>>>></code> <code class="blue">diff(b=8,a=10)</code><br>
|
||||
<code class="green">2</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples of calling the <code>fib()</code> function defined above</div>
|
||||
<p><code>>>></code> <em class="gray">// Fibonacci sequence: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, …​</em><br>
|
||||
<code>>>></code> <code class="blue">fib(6)</code><br>
|
||||
<code class="green">8</code><br>
|
||||
<code>>>></code> <code class="blue">fib(9)</code><br>
|
||||
<code class="green">34</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples of calling the <code>measure()</code> functions defined above</div>
|
||||
<p><code>>>></code> <em class="gray">// simple call</em><br>
|
||||
<code>>>></code> <code class="blue">measure(10,"litre")</code><br>
|
||||
<code class="green">"10 litres"</code><br>
|
||||
<code>>>></code> <em class="gray">// accept the default unit</em><br>
|
||||
<code>>>></code> <code class="blue">measure(8)</code><br>
|
||||
<code class="green">"8 meters"</code><br>
|
||||
<code>>>></code> <em class="gray">// without the required parameter 'value'</em><br>
|
||||
<code>>>></code> <code class="blue">measure(unit="degrees"))</code><br>
|
||||
<code class="red">Eval Error: measure(): missing params — value</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<div class="title">Examples of context binding (closures)</div>
|
||||
<p><code>>>></code> <code class="blue">factory = func(n=2){ func(x){x*n} }</code><br>
|
||||
<code class="green">factory(n=2):any{}</code><br>
|
||||
<code>>>></code> <code class="blue">double = factory()</code><br>
|
||||
<code class="green">double(x):any{}</code><br>
|
||||
<code>>>></code> <code class="blue">triple = factory(3)</code><br>
|
||||
<code class="green">triple(x):any{}</code><br>
|
||||
<code>>>></code> <code class="blue">double(5)</code><br>
|
||||
<code class="green">10</code><br>
|
||||
<code>>>></code> <code class="blue">triple(5)</code><br>
|
||||
<code class="green">15</code></p>
|
||||
</div>
|
||||
<div class="paragraph">
|
||||
<p>Functions compute values in a local context (scope) that do not make effects on the calling context. This is the normal behavior. Using the reference operator <code class="blue">@</code> it is possibile to export local definition to the calling context.</p>
|
||||
@@ -2267,7 +2381,7 @@ These operators have a high priority, in particular higher than the operator <co
|
||||
</div>
|
||||
<div id="footer">
|
||||
<div id="footer-text">
|
||||
Last updated 2024-09-14 11:58:38 +0200
|
||||
Last updated 2024-09-18 20:46:46 +0200
|
||||
</div>
|
||||
</div>
|
||||
</body>
|
||||
|
||||
Reference in New Issue
Block a user