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diff --git a/krebs/4lib/maybe.nix b/krebs/4lib/maybe.nix
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+{ ... }:
+
+rec {
+ Just = x: { type = "maybe"; value = x; };
+ Nothing = { type = "maybe"; };
+ isMaybe = x: builtins.typeOf x == "set" && x.type or false == "maybe";
+ isJust = x: isMaybe x && builtins.hasAttr "value" x;
+ fromJust = x: assert isJust x; x.value;
+ catMaybes = xs: map fromJust (builtins.filter isJust xs);
+}