scala - Why do these similar looking statements yield objects of different types? -


in book 'scala impatient' author provides following 2 examples 'for-comprehension':

for (c <- "hello"; <- 0 1) yield (c + i).tochar  // yields "hieflmlmop"  (i <- 0 1; c <- "hello") yield (c + i).tochar // yields vector('h', 'e', 'l', 'l', 'o', 'i', 'f', 'm', 'm', 'p')

however, didn't mention why output string in first case, , vector in second. please explain? thanks.

your first example translated like:

"hello".flatmap(c => (0 1).map(i => (c + i).tochar))

and second to

(0 1).flatmap(i => "hello".map(c => (c + i).tochar))

stringops.flatmap returns string, first example returns string well. range.flatmap returns indexedseq instead.


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