hydra.lib.maps.ToList Maven / Gradle / Ivy

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package hydra.lib.maps;

import hydra.Flows;
import hydra.compute.Flow;
import hydra.core.Name;
import hydra.core.Term;
import hydra.core.TypeScheme;
import hydra.dsl.Expect;
import hydra.dsl.Terms;
import hydra.graph.Graph;
import hydra.tools.PrimitiveFunction;
import hydra.util.Tuple;

import java.util.List;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

import static hydra.dsl.Types.function;
import static hydra.dsl.Types.list;
import static hydra.dsl.Types.map;
import static hydra.dsl.Types.pair;
import static hydra.dsl.Types.scheme;
import static hydra.dsl.Types.variable;


public class ToList extends PrimitiveFunction {
    public Name name() {
        return new Name("hydra/lib/maps.toList");
    }

    @Override
    public TypeScheme type() {
        return scheme("k", "v", function(
                map("k", "v"),
                list(pair(variable("k"), variable("v")))));
    }

    @Override
    protected Function, Flow> implementation() {
        return args -> {
            Flow> r = Expect.map(Flows::pure, Flows::pure, args.get(0));
            return Flows.map(r, map -> Terms.list(apply(map).stream().map(Terms::pair).collect(Collectors.toList())));
        };
    }

    /**
     * Apply the function to its single argument.
     */
    public static  List> apply(Map map) {
        List> pairs = new java.util.ArrayList<>(map.size());
        for (Map.Entry entry : map.entrySet()) {
            pairs.add(new Tuple.Tuple2<>(entry.getKey(), entry.getValue()));
        }
        return pairs;
    }
}