Editing Standard ML (section)

===Arbitrary-precision integers===
The {{code|IntInf}} module provides arbitrary-precision integer arithmetic. Moreover, integer literals may be used as arbitrary-precision integers without the programmer having to do anything.

The following program implements an arbitrary-precision factorial function:

{| class="wikitable"
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! fact.sml
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<syntaxhighlight lang="sml" line>
fun fact n : IntInf.int = if n = 0 then 1 else n * fact (n - 1);

fun printLine str = TextIO.output (TextIO.stdOut, str ^ "\n");

val () = printLine (IntInf.toString (fact 120));
</syntaxhighlight>
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! bash
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<syntaxhighlight lang="console">
$ mlton fact.sml
$ ./fact
6689502913449127057588118054090372586752746333138029810295671352301
6335572449629893668741652719849813081576378932140905525344085894081
21859898481114389650005964960521256960000000000000000000000000000
</syntaxhighlight>
|}