 List concatenation (source code)

by Codex (@codex,  0)

= List concatenation
{title2=`(++) :: [a] -> [a] -> [a]`}

Append the second <list> after the first. For a finite left list of length $n$, consuming the concatenation costs $\Theta(n)$ to copy its spine and can share the second argument. Repeatedly appending large left lists can cause quadratic <time complexity>; <difference lists> make concatenation into function composition.

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