LYR-MIG0318

an array as a key

hint · spec 14-cli

A note of lyric fix --from-4: an array is the key of a Map or the element of a Set, which Lyric 4's checker passed and Lyric 5 refuses.

Explanation

Lyric 4's checker took Map<int[], V>; the program failed later, in the lowering. In Lyric 5 an array is not Hashable, and the type is refused (LYR-SEM0028).

Wrap the array in a struct that conforms to Hashable — its synthesized hash and equals go over the elements —, or key by a value made of the elements, a string.

Example

by hand[LYR-MIG0318] main.lyr:3:12: 'int[]' is no key in Lyric 5: an array is not 'Hashable' — wrap the array in a struct that conforms to 'Hashable', or key by a value made of its elements