Sow

Sends a value to the nearest enclosing Reap, and returns it.

✓ checked against that system · ! checked, with disagreements (hover a chip)Wolfram LanguageSow✓↗

Sow(e)Records $e$ (evaluated) into the nearest enclosing Reap's untagged group, and returns $e$.

Sow(e, tag)Like $Sow(e)$, but records under $tag$ instead of the untagged group.

Typed signatures

Type	Package	Applies
(any, any?) -> any	combinatorics	always

Domain: Collections

Details

• A $Sow$ with no enclosing $Reap$ is a no-op — it still returns $e$, nothing is recorded anywhere.
• A $Sow$ inside a NESTED $Reap$ feeds only the innermost one; it does not also reach further out, matching Wolfram (an inner $Reap$ "consumes" what's sown inside it).

Examples

Basic #

Sow feeds the nearest Reap

live ↗

In$\mathrm{Reap}(\mathrm{Sow}(5))$Out$\bigl\lbrack5, \bigl\lbrack\bigl\lbrack5\bigr\rbrack\bigr\rbrack\bigr\rbrack$

Sow outside any Reap is a no-op that still returns its value

live ↗

In$\mathrm{Sow}(7)$Out$7$

live ↗

In$\mathrm{Reap}(\sum_{k=10}(\mathrm{Sow}(k^2)+1))$Out$\bigl\lbrack395, \bigl\lbrack\bigl\lbrack1, 4, 9, 16, 25, 36, 49, 64, 81, 100\bigr\rbrack\bigr\rbrack\bigr\rbrack$

Applications #

live ↗

In$\mathrm{Reap}(\mathrm{Do}(\mathrm{Sow}(k, k^2\bmod10), \bigl\lbrack k, 20\bigr\rbrack))$Out$\bigl\lbrack\mathrm{Null}, \bigl\lbrack\bigl\lbrack1, 9, 11, 19\bigr\rbrack, \bigl\lbrack2, 8, 12, 18\bigr\rbrack, \bigl\lbrack3, 7, 13, 17\bigr\rbrack, \bigl\lbrack4, 6, 14, 16\bigr\rbrack, \bigl\lbrack5, 15\bigr\rbrack, \bigl\lbrack10, 20\bigr\rbrack\bigr\rbrack\bigr\rbrack$

Properties #

Outside a collector, Sow simply returns its argument

live ↗

In$\mathrm{Sow}(x)$Out$x$

About

Examples	5
Checked against	Wolfram Language 5 agree
Crosswalk	Wolfram Language

See also: Reap