The reason List.map (someFunction apple) bananas Is faster is because the curried call returns a single-arity function which will be executed directly by List.map, while List.map (\apples banana -> someFunction apples banana) bananas will have to create a curried version of the lambda (with F2, which has some overhead) and then List.map essentially calls two functions when executing (first the lambda through A2, then someFunction through A2).
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