1 files changed, 37 insertions, 0 deletions
diff --git a/src/libzisp/value/double.zig b/src/libzisp/value/double.zig
new file mode 100644
index 0000000..5c98324
--- /dev/null
+++ b/src/libzisp/value/double.zig
@@ -0,0 +1,37 @@
+const Value = @import("../value.zig").Value;
+
+// Zig API
+
+/// Checks for a Zisp double (double, +inf, -inf, or canonical NaN).
+pub fn check(v: Value) bool {
+    return !v.isPacked();
+}
+
+/// Asserts check().
+pub fn assert(v: Value) void {
+    if (!check(v)) {
+        v.dump();
+        @panic("not double");
+    }
+}
+
+pub fn pack(d: f64) Value {
+    return .{ .double = d };
+}
+
+pub fn unpack(v: Value) f64 {
+    assert(v);
+    return v.double;
+}
+
+// Zisp API
+
+pub fn pred(v: Value) Value {
+    return Value.boole.pack(check(v));
+}
+
+pub fn add(v1: Value, v2: Value) Value {
+    const d1 = unpack(v1);
+    const d2 = unpack(v2);
+    return pack(d1 + d2);
+}