85 lines
2.1 KiB
Nix
85 lines
2.1 KiB
Nix
{
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attrs,
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result,
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...
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}: rec {
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cmpStructErr' = errBadKeys: errBadValues: path: S: T:
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if builtins.isAttrs S && builtins.isAttrs T
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then let
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keysS = builtins.attrNames S;
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keysT = builtins.attrNames T;
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in
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# ensure all key names match, then recurse
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if !(keysS == keysT)
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then errBadKeys path keysS keysT
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else
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(result.firstErr
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(builtins.map
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(k: cmpStructErr' errBadKeys errBadValues (path ++ [k]) (keysS.${k}) (keysT.${k}))
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keysS))
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else
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# terminating leaf in recursion tree reached
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# ensure values' types match
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(builtins.typeOf S == builtins.typeOf T)
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|| errBadValues path S T;
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cmpStructErr = errBadKeys: errBadValues: cmpStructErr' errBadKeys errBadValues [];
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cmpStruct =
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cmpStructErr
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(path: keysS: keysT:
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result.Err {
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reason = "keys";
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inherit path;
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})
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(path: S: T:
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result.Ok "ok");
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cmpTypedStruct =
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cmpStructErr
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(path: keysS: keysT:
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result.Err {
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reason = "keys";
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inherit path;
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})
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(path: S: T:
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result.Err {
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reason = "values";
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inherit path;
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});
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cmpTypedPartialStruct =
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cmpStructErr
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(path: keysS: keysT:
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result.Ok "ok")
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(path: S: T:
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result.Err {
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reason = "values";
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inherit path;
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});
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# check is a function taking two structs
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# and returning a result monad.
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mergeStruct' = check: template: S: let
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res = check template S;
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in
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result.errOr res ({...}:
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result.Ok (
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attrs.mapAttrsRecursive (
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path: value: let
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valueS = attrs.attrValueAt S path;
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in
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if valueS != null
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then valueS
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else value
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)
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template
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));
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# mergeStruct ensures no properties are evaluated (entirely lazy)
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mergeStruct = mergeStruct' (S: T: result.Ok "ok");
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# mergeTypedPartialStruct must evaluate properties (not lazy)
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# for lazy evaluation use mergeStruct instead!
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mergeTypedPartialStruct = mergeStruct' cmpTypedPartialStruct;
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}
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