MathAction #108 InfiniteTuple and Stream

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Section 5.6 An Example: [Streams]? of Primes

of the Axiom Book says: "This is how you use generate to generate an infinite stream of primes." In FriCAS, the function generate has been renamed to stream.

fricas

(1) -> primes := stream(nextPrime,2)

$\label{eq1}\left[ 2, \: 3, \: 5, \: 7, \:{11}, \:{13}, \:{17}, \:{19}, \:{2 3}, \:{29}, \: \ldots \right]$

(1)

Type: InfiniteTuple?(Integer)

but the result is an InfiniteTuple?, not a Stream. The domain InfiniteTuple? is not documented in the book.

To create a stream one must explicitly write:

fricas

primes := stream(nextPrime,2)$Stream Integer

$\label{eq2}\left[ 2, \: 3, \: 5, \: 7, \:{11}, \:{13}, \:{17}, \:{19}, \:{2 3}, \:{29}, \: \ldots \right]$

(2)

Type: Stream(Integer)

fricas

primes := construct stream(nextPrime,2)

$\label{eq3}\left[ 2, \: 3, \: 5, \: 7, \:{11}, \:{13}, \:{17}, \:{19}, \:{2 3}, \:{29}, \: \ldots \right]$

(3)

Type: Stream(Integer)

... --oldk1331, Wed, 12 Jul 2017 14:24:44 +0000 reply

In ituple.spad, you can see that InfiniteTuple? is represented as Stream. And there is special treatment for InfiniteTuple? in interpreter code. Maybe InfiniteTuple? can be removed, to be investigated.

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