The stdlib function ⎕make_lazy

Lazy and eager shapes

A normal Pometo shape is an eager vector - it knows how long it is:

It is defined by this Erlang record:

-record('$shape¯', {
                    shaping    = eager, % [eager | lazy]
                    indexed    = false,
                    dimensions = [],
                    forcing    = none,
                    type       = none,
                    line_no    = none,
                    char_no    = none
                   }).

A normal eager vector 1 2 3 looks like this internally - shaping is eager and the dimensions are known:

{'$ast¯',{'$shape¯',eager,false,[3],none,number,1,19},[1,2,3],1,19}

The stdlib function ⎕make_indexed takes one of these and converts it to a lazy vector, one which doesn’t know how long it is:

{'$ast¯',{'$shape¯',lazy,false,unsized_vector,none,number,1,16},
                [1,2,3],
                1,16}

For more details please see the discussion in the discussion of ⎕make_indexed.