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Anonymous recursion: Difference between revisions

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Anonymous recursion (view source)

Revision as of 15:02, 29 December 2021

7,054 bytes added ,  2 years ago
m
→‎{{header|Phix}}: added syntax colouring, marked p2js incompatible
(Anonymous recursion en QBasic)
m (→‎{{header|Phix}}: added syntax colouring, marked p2js incompatible)
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=={{header|Phix}}==
{{libheader|Phix/Class}}
Needs 0.8.1+
===using classes===
With proof that the private fib_i() does not pollute the outer namespace.
<!--<lang Phix>class Fib(notonline)-->
<span style="color: #008080;">without</span> <span style="color: #008080;">js</span> <span style="color: #000080;font-style:italic;">-- (no class yet)</span>
private function fib_i(integer n)
<span style="color: #008080;">class</span> <span style="color: #000000;">Fib</span>
return iff(n<2?n:this.fib_i(n-1)+this.fib_i(n-2))
<span style="color: #008080;">private</span> <span style="color: #008080;">function</span> <span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
end function
<span style="color: #008080;">return</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;"><</span><span style="color: #000000;">2</span><span style="color: #0000FF;">?</span><span style="color: #000000;">n</span><span style="color: #0000FF;">:</span><span style="color: #7060A8;">this</span><span style="color: #0000FF;">.</span><span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">)+</span><span style="color: #7060A8;">this</span><span style="color: #0000FF;">.</span><span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">2</span><span style="color: #0000FF;">))</span>
public function fib(integer n)
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
if n<0 then throw("constraint error") end if
<span style="color: #008080;">public</span> <span style="color: #008080;">function</span> <span style="color: #000000;">fib</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
return this.fib_i(n)
<span style="color: #008080;">if</span> <span style="color: #000000;">n</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">throw</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"constraint error"</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
end function
<span style="color: #008080;">return</span> <span style="color: #7060A8;">this</span><span style="color: #0000FF;">.</span><span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
end class
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
Fib f = new()
<span style="color: #008080;">end</span> <span style="color: #008080;">class</span>
 
<span style="color: #000000;">Fib</span> <span style="color: #000000;">f</span> <span style="color: #0000FF;">=</span> <span style="color: #7060A8;">new</span><span style="color: #0000FF;">()</span>
function fib_i(integer i)
return sprintf("this is not the fib_i(%d) you are looking for\n",i)
<span style="color: #008080;">function</span> <span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">i</span><span style="color: #0000FF;">)</span>
end function
<span style="color: #008080;">return</span> <span style="color: #7060A8;">sprintf</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"this is not the fib_i(%d) you are looking for\n"</span><span style="color: #0000FF;">,</span><span style="color: #000000;">i</span><span style="color: #0000FF;">)</span>
 
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
?f.fib(10)
--?f.fib_i(10) -- illegal
<span style="color: #0000FF;">?</span><span style="color: #000000;">f</span><span style="color: #0000FF;">.</span><span style="color: #000000;">fib</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)</span>
?fib_i(10)</lang>
<span style="color: #000080;font-style:italic;">--?f.fib_i(10) -- illegal</span>
<span style="color: #0000FF;">?</span><span style="color: #000000;">fib_i</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)</span>
<!--</lang>-->
{{out}}
<pre>
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Obviously the inner function does not have to and in fact is not allowed to have a name itself, but it needs to be stored in something with a name before it can be called,
and in being anonymous, in order to effect recursion it must be passed to itself, repeatedly and not really anonymous at all anymore.
<!--<lang Phix>function erm(integer n, fnotonline)-->
<span style="color: #008080;">without</span> <span style="color: #008080;">js</span> <span style="color: #000080;font-style:italic;">-- (no lambda yet)</span>
return f(n,f)
<span style="color: #008080;">function</span> <span style="color: #000000;">erm</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span> <span style="color: #000000;">f</span><span style="color: #0000FF;">)</span>
end function
<span style="color: #008080;">return</span> <span style="color: #000000;">f</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">)</span>
 
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
function fib(integer n)
if n<0 then throw("constraint error") end if
<span style="color: #008080;">function</span> <span style="color: #000000;">fib</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">)</span>
return erm(n,function(integer n,f) return iff(n<2?n:f(n-1,f)+f(n-2,f)) end function)
<span style="color: #008080;">if</span> <span style="color: #000000;">n</span><span style="color: #0000FF;"><</span><span style="color: #000000;">0</span> <span style="color: #008080;">then</span> <span style="color: #008080;">throw</span><span style="color: #0000FF;">(</span><span style="color: #008000;">"constraint error"</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">end</span> <span style="color: #008080;">if</span>
end function
<span style="color: #008080;">return</span> <span style="color: #000000;">erm</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #008080;">function</span><span style="color: #0000FF;">(</span><span style="color: #004080;">integer</span> <span style="color: #000000;">n</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">)</span> <span style="color: #008080;">return</span> <span style="color: #008080;">iff</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;"><</span><span style="color: #000000;">2</span><span style="color: #0000FF;">?</span><span style="color: #000000;">n</span><span style="color: #0000FF;">:</span><span style="color: #000000;">f</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">1</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">)+</span><span style="color: #000000;">f</span><span style="color: #0000FF;">(</span><span style="color: #000000;">n</span><span style="color: #0000FF;">-</span><span style="color: #000000;">2</span><span style="color: #0000FF;">,</span><span style="color: #000000;">f</span><span style="color: #0000FF;">))</span> <span style="color: #008080;">end</span> <span style="color: #008080;">function</span><span style="color: #0000FF;">)</span>
 
<span style="color: #008080;">end</span> <span style="color: #008080;">function</span>
?fib(10)</lang>
<span style="color: #0000FF;">?</span><span style="color: #000000;">fib</span><span style="color: #0000FF;">(</span><span style="color: #000000;">10</span><span style="color: #0000FF;">)</span>
<!--</lang>-->
{{out}}
<pre>
Petelomax
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