50 lines
932 B
Nix
50 lines
932 B
Nix
{lists, ...}: rec {
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# Result Monad
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Ok = value: {
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ok = true;
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value = value;
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};
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Err = err: {
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ok = false;
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error = err;
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};
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# Pattern Matching
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isResult = r:
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(builtins.length (builtins.attrNames r) == 2)
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&& builtins.hasAttr "ok" r
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&& (builtins.hasAttr "value" r || builtins.hasAttr "error" r);
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isOk = r: isResult r && r.ok;
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isErr = r: isResult r && !r.ok;
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# Unwrap (Monadic Return Operation)
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unwrap = f: r:
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if isOk r
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then r.value
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else f r.error;
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unwrapDefault = default: unwrap (x: default);
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# Map (Monadic Bind Operation)
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identity = r: r;
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map = r: f: g:
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if isOk r
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then Ok (f r.value)
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else Err (g r.value);
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mapOk = f: map f identity;
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mapErr = f: map identity f;
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# Conditionals
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okOr = r: f:
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if isOk r
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then r
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else f r;
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errOr = r: f:
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if isErr r
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then r
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else f r;
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firstErr = lists.findFirst isErr (Ok "No errors");
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}
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