layout

Michelson does not natively support records or variants. These have to be encoded using nested pair or or type constructors, therefore many tree representations could translate to the same linear sequence of fields or constructors, depending on the traversal.

LIGO enables to choose between a right comb, which preserves the order of the fields or constructors as declared in the source code, and a left-balanced, alphabetically ordered binary tree.

The decorators @layout("comb") and @layout("tree") can be placed before a record type expression (that is, before { ... }), and before the leading vertical bar | of a variant type expression, in order to explicitly choose the desired layout.

For example,

type transfer =

@layout("comb")

{ @annot("from") address_from: address;

@annot("to") address_to: address;

value: nat }

Note that the default layout is comb, and, except for inter-operations with pre-1.0.0, it should not be updated.