CODEWITHSUNDEEP
tuplesiterationjulia
Kirnap
Kirnap

Reputation: 17

Unexpected tuple iteration in Julia?

I wanted to iterate over triplets in a tuple and found a weird comma detail in Julia is that what we should expect? 

julia> for (k, n, d) in (("x1", "x2", "x3"),); @show k, n, d; end;
(k, n, d) = ("x1", "x2", "x3")    
# However if I remove , it doesn't work
julia> for (k, n, d) in (("x1", "x2", "x3")); @show k, n, d; end;
ERROR: BoundsError
Stacktrace:
[1] indexed_next(::String, ::Int64, ::Int64) at ./tuple.jl:56
[2] anonymous at ./<missing>:?

Upvotes: 1

Views: 139

Answers (1)

mbauman
mbauman

Reputation: 31342

Yes, this is behaving as expected. Parentheses alone do not create tuples. If they did, simply basic math expressions like 2*(3+4) wouldn't work. Parentheses without commas or semicolons in them are used for precedence groupings or function calls. That's why you need that explicit trailing comma in the one-tuple case.

((x,y,z)) is the same as (x,y,z). ((x,y,z),) constructs a one-tuple that contains (x,y,z).

Upvotes: 5

Related Questions