86 lines
2.2 KiB
Markdown
86 lines
2.2 KiB
Markdown
yants
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=====
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[](https://travis-ci.org/tazjin/yants)
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This is a tiny type-checker for data in Nix, written in Nix.
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# Features
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* Checking of primitive types (`int`, `string` etc.)
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* Checking polymorphic types (`option`, `list`, `either`)
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* Defining & checking struct/record types
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* Defining & matching enum types
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* Defining & matching sum types
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* Defining function signatures (including curried functions)
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* Types are composable! `option string`! `list (either int (option float))`!
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* Type errors also compose!
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Currently lacking:
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* Any kind of inference
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* Convenient syntax for attribute-set function signatures
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## Primitives & simple polymorphism
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## Structs
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## Nested structs!
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## Enums!
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## Functions!
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# Usage
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Yants can be imported from its `default.nix`. A single attribute (`lib`) can be
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passed, which will otherwise be imported from `<nixpkgs>`.
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Examples for the most common import methods would be:
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1. Import into scope with `with`:
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```nix
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with (import ./default.nix {});
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# ... Nix code that uses yants ...
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```
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2. Import as a named variable:
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```nix
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let yants = import ./default.nix {};
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in yants.string "foo" # or other uses ...
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````
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3. Overlay into `pkgs.lib`:
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```nix
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# wherever you import your package set (e.g. from <nixpkgs>):
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import <nixpkgs> {
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overlays = [
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(self: super: {
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lib = super.lib // { yants = import ./default.nix { inherit (super) lib; }; };
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})
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];
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}
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# yants now lives at lib.yants, besides the other library functions!
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```
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Please see my [Nix one-pager](https://github.com/tazjin/nix-1p) for more generic
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information about the Nix language and what the above constructs mean.
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# Stability
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The current API of Yants is **not yet** considered stable, but it works fine and
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should continue to do so even if used at an older version.
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Yants' tests use Nix versions above 2.2 - compatibility with older versions is
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not guaranteed.
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