Catamorphism: Difference between revisions
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=={{header|Binary Lambda Calculus}}==
A minimal size (right) fold in lambda calculus is <code>fold = \f\z (let go = \l.l(\h\t\z.f h (go t))z in go)</code> which corresponds to the 69-bit BLC program
<pre>000001000110100000010110000000010111111110111001011111101111101101110</pre>
=={{header|BQN}}==
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say reduce &infix:<max>, @list;
say reduce &infix:<lcm>, @list;</syntaxhighlight>
=={{header|Refal}}==
<syntaxhighlight lang="refal">$ENTRY Go {
, 1 2 3 4 5 6 7: e.List
= <Prout <Reduce Add e.List>>
<Prout <Reduce Mul e.List>>;
};
Reduce {
s.F t.I = t.I;
s.F t.I t.J e.X = <Reduce s.F <Mu s.F t.I t.J> e.X>;
};</syntaxhighlight>
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=={{header|REXX}}==
This REXX example is modeled after the Raku example (it is NOT a translation).
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LCM: 2520
</pre>
=={{header|Ring}}==
<syntaxhighlight lang="ring">
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≪ → array op
≪ array 1 GET 2
'''WHILE''' DUP array SIZE ≤ '''REPEAT'''
array OVER GET ROT SWAP op EVAL
SWAP 1 +
'''END''' DROP
≫ ≫ '<span style="color:blue">REDUCE</span>' STO
[ 1 2 3 4 5 6 7 8 9 10 ] ≪ + ≫ <span style="color:blue">REDUCE</span>
[ 1 2 3 4 5 6 7 8 9 10 ] ≪ - ≫ <span style="color:blue">REDUCE</span>
[ 1 2 3 4 5 6 7 8 9 10 ] ≪ * ≫ <span style="color:blue">REDUCE</span>
[ 1 2 3 4 5 6 7 8 9 10 ] ≪ MAX ≫ <span style="color:blue">REDUCE</span>
[ 1 2 3 4 5 6 7 8 9 10 ] ≪ SQ + ≫ <span style="color:blue">REDUCE</span>
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<pre>
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1: 385
</pre>
From HP-48G models, a built-in function named <code>STREAM</code> performs exactly the same as the above <code>REDUCE</code> one, but only with lists.
=={{header|Ruby}}==
The method inject (and it's alias reduce) can be used in several ways; the simplest is to give a methodname as argument:
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===Reduce a slice===
<syntaxhighlight lang="zig">/// Asserts that `
pub fn reduce(comptime T: type, comptime applyFn: fn (T, T) T, array: []const T) T {
var val: T = array[0];
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