{ lib }: rec { /** Throw if pred is false, else return pred. Intended to be used to augment asserts with helpful error messages. # Inputs `pred` : Predicate that needs to succeed, otherwise `msg` is thrown `msg` : Message to throw in case `pred` fails # Type ``` assertMsg :: Bool -> String -> Bool ``` # Examples :::{.example} ## `lib.asserts.assertMsg` usage example ```nix assertMsg false "nope" stderr> error: nope assert assertMsg ("foo" == "bar") "foo is not bar, silly"; "" stderr> error: foo is not bar, silly ``` ::: */ # TODO(Profpatsch): add tests that check stderr assertMsg = pred: msg: pred || builtins.throw msg; /** Specialized `assertMsg` for checking if `val` is one of the elements of the list `xs`. Useful for checking enums. # Inputs `name` : The name of the variable the user entered `val` into, for inclusion in the error message `val` : The value of what the user provided, to be compared against the values in `xs` `xs` : The list of valid values # Type ``` assertOneOf :: String -> ComparableVal -> List ComparableVal -> Bool ``` # Examples :::{.example} ## `lib.asserts.assertOneOf` usage example ```nix let sslLibrary = "libressl"; in assertOneOf "sslLibrary" sslLibrary [ "openssl" "bearssl" ] stderr> error: sslLibrary must be one of [ stderr> "openssl" stderr> "bearssl" stderr> ], but is: "libressl" ``` ::: */ assertOneOf = name: val: xs: assertMsg (lib.elem val xs) "${name} must be one of ${ lib.generators.toPretty {} xs}, but is: ${ lib.generators.toPretty {} val}"; /** Specialized `assertMsg` for checking if every one of `vals` is one of the elements of the list `xs`. Useful for checking lists of supported attributes. # Inputs `name` : The name of the variable the user entered `val` into, for inclusion in the error message `vals` : The list of values of what the user provided, to be compared against the values in `xs` `xs` : The list of valid values # Type ``` assertEachOneOf :: String -> List ComparableVal -> List ComparableVal -> Bool ``` # Examples :::{.example} ## `lib.asserts.assertEachOneOf` usage example ```nix let sslLibraries = [ "libressl" "bearssl" ]; in assertEachOneOf "sslLibraries" sslLibraries [ "openssl" "bearssl" ] stderr> error: each element in sslLibraries must be one of [ stderr> "openssl" stderr> "bearssl" stderr> ], but is: [ stderr> "libressl" stderr> "bearssl" stderr> ] ``` ::: */ assertEachOneOf = name: vals: xs: assertMsg (lib.all (val: lib.elem val xs) vals) "each element in ${name} must be one of ${ lib.generators.toPretty {} xs}, but is: ${ lib.generators.toPretty {} vals}"; }