Enumerator::Lazy#filter_map

[U] () { (Elem elem) -> (nil | false | U) } -> ::Array[U]

() -> ::Enumerator[Elem, ::Array[untyped]]

lazy.filter_map { |obj| block } → lazy_enumerator

static VALUE
lazy_filter_map(VALUE obj)
{
    if (!rb_block_given_p()) {
        rb_raise(rb_eArgError, "tried to call lazy filter_map without a block");
    }

    return lazy_add_method(obj, 0, 0, Qnil, Qnil, &lazy_filter_map_funcs);
}

Like Enumerable#filter_map, but chains operation to be lazy-evaluated.

Example

(1..).lazy.filter_map { |i| i * 2 if i.even? }.first(5)
#=> [4, 8, 12, 16, 20]

See also #filter #find_all #enum_for #flat_map also in 4.1 · 4.0 · 3.3 · 3.2 · 3.1 · 3.0

‹ prev#filter next ›#find_all