Method fusion, or shortcut fusion, combines chained operations into fewer passes over a data structure. In JavaScript, replacing map(...).map(...) with one map and a composed function avoids intermediate arrays, reducing memory allocation and execution overhead. section 5.4.2
Fusing array transformations
These forms produce the same result, but the composed version performs one map instead of three and avoids multiple array copies: ['aa','bb','cc'].map(compose(toUpper, join, unique)); ['aa','bb','cc'].map(unique).map(join).map(toUpper); section 5.4.2
['aa','bb','cc'].map(
compose(
toUpper,
join,
unique
)
);
Use the composed array transformation as a compact illustration of fusing several map operations into one pass. section 5.4.2
