59 lines
1.7 KiB
Nix
59 lines
1.7 KiB
Nix
final: prev:
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let lib = final;
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in with lib; {
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generators = with final.generators;
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prev.generators // {
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/* Generates text-encoded Preserves from an arbitrary value.
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Records are generated for lists with a final element in
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the form of `{ record = «label»; }`.
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Type: toPreserves :: a -> string
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Example:
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toPreserves { } [{ a = 0; b = 1; } "c" [ true false ] { record = "foo"; }]
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=> "<foo { a: 0 b: 1 } \"c\" [ #t #f ]>"
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*/
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toPreserves = { }@args:
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let
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toPreserves' = toPreserves args;
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concatItems = toString;
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recordLabel = list:
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with builtins;
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let len = length list;
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in if len == 0 then
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null
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else
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let end = elemAt list (len - 1);
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in if (isAttrs end) && (attrNames end) == [ "record" ] then
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end
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else
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null;
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in v:
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if isAttrs v then
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"{ ${
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concatItems (lib.attrsets.mapAttrsToList
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(key: val: "${key}: ${toPreserves' val}") v)
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} }"
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else if isList v then
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let label = recordLabel v;
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in if label == null then
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"[ ${concatItems (map toPreserves' v)} ]"
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else
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"<${label.record} ${
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concatItems (map toPreserves' (lib.lists.init v))
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}>"
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else if isBool v then
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(if v then "#t" else "#f")
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else if isFunction v then
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abort "generators.toPreserves: cannot convert a function to Preserves"
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else if isNull v then
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"null"
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else
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builtins.toJSON v;
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};
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}
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