//
// mapValues
//

function mapValues;
[f, first, ...rest]
overload mapValues(f, first, ...rest) = f(first), ...mapValues(f, ...rest);
[f]
overload mapValues(f) = ;



//
// clay types as symbols
//

symbol Bool;
symbol Int;
symbol Array[T,n];
symbol Tuple[...T];

symbol RecordTag;

[...fields]
recordType(...fields) = (RecordTag, fieldNames(...fields), fieldTypes(...fields));

[...fields]
fieldNames(...fields) = (...mapValues(f => tupleElement(f, 0), ...fields));

[...fields]
fieldTypes(...fields) = (...mapValues(f => tupleElement(f, 1), ...fields));

[t]
record?(t) =
    symbolWithBody?(t)
    and tupleWithTag?(symbolBody(t), RecordTag);

[x]
symbolWithBody?(x) = symbol?(x) and symbolHasBody?(x);

[x, tag]
tupleWithTag?(x, tag) =
    tuple?(x)
    and lesser?(0, tupleSize(x))
    and equals?(tupleElement(x, 0), tag);

[t | record?(t)]
recordFieldCount(t) = tupleSize(tupleElement(symbolBody(t), 1));

[t | record?(t)]
recordFieldNames(t) = tupleElement(symbolBody(t), 1);

[t | record?(t)]
recordFieldTypes(t) = tupleElement(symbolBody(t), 2);


symbol Point[T] = recordType(
    ("x", T),
    ("y", T),
);

[t | record?(t)]
recordInfo(t) = (t, recordFieldNames(t), recordFieldTypes(t));

main() = recordInfo(Point[Int]);