separate expr into types and shorthands
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Nix/Atoms.hs
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48
Nix/Atoms.hs
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@ -0,0 +1,48 @@
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module Nix.Atoms where
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import Prelude
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import Data.Text (Text, pack)
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import GHC.Generics
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import Data.Data
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import Data.HashMap.Strict (HashMap)
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-- | Atoms are values that evaluate to themselves. This means that
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-- they appear in both the parsed AST (in the form of literals) and
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-- the evaluated form.
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data NAtom
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-- | An integer. The c nix implementation currently only supports
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-- integers that fit in the range of 'Int64'.
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= NInt !Integer
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-- | Booleans.
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| NBool !Bool
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-- | Null values. There's only one of this variant.
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| NNull
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-- | URIs, which are just string literals, but do not need quotes.
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| NUri !Text
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deriving (Eq, Ord, Generic, Typeable, Data, Show)
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class ToAtom t where
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toAtom :: t -> NAtom
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instance ToAtom Bool where toAtom = NBool
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instance ToAtom Int where toAtom = NInt . fromIntegral
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instance ToAtom Integer where toAtom = NInt
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class FromAtom t where
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fromAtom :: NAtom -> t
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fromAtoms :: [NAtom] -> t
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fromAtomSet :: HashMap Text NAtom -> t
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-- | Convert a primitive into something which can be made from a
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-- constant. So for example `convert 1 :: Expression`
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convert :: (ToAtom prim, FromAtom t) => prim -> t
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convert = fromAtom . toAtom
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-- | Conversion to environment variables for constants.
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atomToEnvString :: NAtom -> Text
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atomToEnvString = \case
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NInt i -> pack $ show i
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NBool True -> "1"
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NBool False -> ""
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NNull -> ""
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NUri uri -> uri
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@ -17,6 +17,7 @@ import Data.Typeable (Typeable)
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import GHC.Generics
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import GHC.Generics
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import Nix.Pretty (atomText)
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import Nix.Pretty (atomText)
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import Nix.StringOperations (runAntiquoted)
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import Nix.StringOperations (runAntiquoted)
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import Nix.Atoms
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import Nix.Expr
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import Nix.Expr
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import Prelude hiding (mapM, sequence)
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import Prelude hiding (mapM, sequence)
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321
Nix/Expr.hs
321
Nix/Expr.hs
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@ -1,315 +1,8 @@
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{-# LANGUAGE FlexibleInstances #-}
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-- | Wraps the expression submodules.
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{-# LANGUAGE DeriveTraversable #-}
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module Nix.Expr (
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{-# LANGUAGE DeriveFoldable #-}
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module Nix.Expr.Types,
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{-# LANGUAGE DeriveGeneric #-}
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module Nix.Expr.Shorthands
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{-# LANGUAGE DeriveDataTypeable #-}
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) where
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{-# LANGUAGE DeriveFunctor #-}
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{-# LANGUAGE OverloadedStrings #-}
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{-# LANGUAGE LambdaCase #-}
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-- | The nix expression type and supporting types.
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module Nix.Expr where
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import Control.Monad hiding (forM_, mapM, sequence)
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import Data.Data
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import Data.Fix
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import Data.Foldable
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import Data.Map (Map)
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import qualified Data.Map as Map
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import Data.Monoid
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import Data.Text (Text, pack)
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import Data.Traversable
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import GHC.Exts
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import GHC.Generics
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import Prelude hiding (readFile, concat, concatMap, elem, mapM,
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sequence, minimum, foldr)
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-- | The main nix expression type. This is polymorphic so that it can be made
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-- a functor, which allows us to traverse expressions and map functions over
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-- them. The actual 'NExpr' type is a fixed point of this functor, defined
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-- below.
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data NExprF r
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= NConstant !NAtom
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-- ^ Constants: ints, bools, URIs, and null.
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| NStr !(NString r)
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-- ^ A string, with interpolated expressions.
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| NSym !Text
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-- ^ A variable. For example, in the expression @f a@, @f@ is represented
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-- as @NSym "f"@ and @a@ as @NSym "a"@.
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| NList ![r]
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-- ^ A list literal.
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| NSet ![Binding r]
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-- ^ An attribute set literal, not recursive.
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| NRecSet ![Binding r]
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-- ^ An attribute set literal, recursive.
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| NLiteralPath !FilePath
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-- ^ A path expression, which is evaluated to a store path. The path here
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-- can be relative, in which case it's evaluated relative to the file in
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-- which it appears.
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| NEnvPath !FilePath
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-- ^ A path which refers to something in the Nix search path (the NIX_PATH
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-- environment variable. For example, @<nixpkgs/pkgs>@.
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| NUnary !NUnaryOp !r
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-- ^ Application of a unary operator to an expression.
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| NBinary !NBinaryOp !r !r
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-- ^ Application of a binary operator to two expressions.
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| NSelect !r !(NAttrPath r) !(Maybe r)
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-- ^ Dot-reference into an attribute set, optionally providing an
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-- alternative if the key doesn't exist.
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| NHasAttr !r !(NAttrPath r)
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-- ^ Ask if a set contains a given attribute path.
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| NAbs !(Params r) !r
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-- ^ A function literal (lambda abstraction).
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| NApp !r !r
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-- ^ Apply a function to an argument.
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| NLet ![Binding r] !r
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-- ^ Evaluate the second argument after introducing the bindings.
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| NIf !r !r !r
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-- ^ If-then-else statement.
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| NWith !r !r
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-- ^ Evaluate an attribute set, bring its bindings into scope, and
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-- evaluate the second argument.
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| NAssert !r !r
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-- ^ Assert that the first returns true before evaluating the second.
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deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show)
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-- | The monomorphic expression type is a fixed point of the polymorphic one.
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type NExpr = Fix NExprF
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-- | Atoms are values that evaluate to themselves. This means that
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-- they appear in both the parsed AST (in the form of literals) and
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-- the evaluated form.
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data NAtom
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-- | An integer. The c nix implementation currently only supports
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-- integers that fit in the range of 'Int64'.
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= NInt !Integer
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-- | Booleans.
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| NBool !Bool
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-- | Null values. There's only one of this variant.
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| NNull
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-- | URIs, which are just string literals, but do not need quotes.
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| NUri !Text
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deriving (Eq, Ord, Generic, Typeable, Data, Show)
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-- | A single line of the bindings section of a let expression or of a set.
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data Binding r
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= NamedVar !(NAttrPath r) !r
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-- ^ An explicit naming, such as @x = y@ or @x.y = z@.
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| Inherit !(Maybe r) ![NKeyName r]
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-- ^ Using a name already in scope, such as @inherit x;@ which is shorthand
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-- for @x = x;@ or @inherit (x) y;@ which means @y = x.y;@.
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deriving (Typeable, Data, Ord, Eq, Functor, Show)
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-- | @Params@ represents all the ways the formal parameters to a
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-- function can be represented.
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data Params r
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= Param !Text
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-- ^ For functions with a single named argument, such as @x: x + 1@.
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| ParamSet !(ParamSet r) !(Maybe Text)
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-- ^ Explicit parameters (argument must be a set). Might specify a name
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-- to bind to the set in the function body.
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deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show,
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Foldable, Traversable)
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-- | An explicit parameter set; provides a shorthand for unpacking arguments.
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data ParamSet r
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= FixedParamSet !(Map Text (Maybe r))
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-- ^ A fixed set, where no arguments beyond what is specified in the map
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-- may be given. The map might contain defaults for arguments not passed.
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| VariadicParamSet !(Map Text (Maybe r))
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-- ^ Same as the 'FixedParamSet', but extra arguments are allowed.
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deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show,
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Foldable, Traversable)
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-- | 'Antiquoted' represents an expression that is either
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-- antiquoted (surrounded by ${...}) or plain (not antiquoted).
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data Antiquoted v r = Plain !v | Antiquoted !r
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deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show)
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-- | An 'NString' is a list of things that are either a plain string
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-- or an antiquoted expression. After the antiquotes have been evaluated,
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-- the final string is constructed by concating all the parts.
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data NString r
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= DoubleQuoted ![Antiquoted Text r]
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-- ^ Strings wrapped with double-quotes (") are not allowed to contain
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-- literal newline characters.
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| Indented ![Antiquoted Text r]
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-- ^ Strings wrapped with two single quotes ('') can contain newlines,
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-- and their indentation will be stripped.
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deriving (Eq, Ord, Generic, Typeable, Data, Functor, Show)
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-- | For the the 'IsString' instance, we use a plain doublequoted string.
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instance IsString (NString r) where
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fromString "" = DoubleQuoted []
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fromString string = DoubleQuoted [Plain $ pack string]
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-- | A 'KeyName' is something that can appear at the right side of an
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-- equals sign. For example, @a@ is a 'KeyName' in @{ a = 3; }@, @let a = 3;
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-- in ...@, @{}.a@ or @{} ? a@.
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--
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-- Nix supports both static keynames (just an identifier) and dynamic
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-- identifiers. Dynamic identifiers can be either a string (e.g.:
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-- @{ "a" = 3; }@) or an antiquotation (e.g.: @let a = "example";
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-- in { ${a} = 3; }.example@).
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--
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-- Note: There are some places where a dynamic keyname is not allowed.
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-- In particular, those include:
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--
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-- * The RHS of a @binding@ inside @let@: @let ${"a"} = 3; in ...@
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-- produces a syntax error.
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-- * The attribute names of an 'inherit': @inherit ${"a"};@ is forbidden.
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--
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-- Note: In Nix, a simple string without antiquotes such as @"foo"@ is
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-- allowed even if the context requires a static keyname, but the
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-- parser still considers it a 'DynamicKey' for simplicity.
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data NKeyName r
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= DynamicKey !(Antiquoted (NString r) r)
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| StaticKey !Text
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deriving (Eq, Ord, Generic, Typeable, Data, Show)
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-- | Deriving this instance automatically is not possible because @r@
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-- occurs not only as last argument in @Antiquoted (NString r) r@
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instance Functor NKeyName where
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fmap f (DynamicKey (Plain str)) = DynamicKey . Plain $ fmap f str
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fmap f (DynamicKey (Antiquoted e)) = DynamicKey . Antiquoted $ f e
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fmap _ (StaticKey key) = StaticKey key
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-- | A selector (for example in a @let@ or an attribute set) is made up
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-- of strung-together key names.
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type NAttrPath r = [NKeyName r]
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-- | There are two unary operations: logical not and integer negation.
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data NUnaryOp = NNeg | NNot
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deriving (Eq, Ord, Generic, Typeable, Data, Show)
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-- | Binary operators expressible in the nix language.
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data NBinaryOp
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= NEq -- ^ Equality (==)
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| NNEq -- ^ Inequality (!=)
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| NLt -- ^ Less than (<)
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| NLte -- ^ Less than or equal (<=)
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| NGt -- ^ Greater than (>)
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| NGte -- ^ Greater than or equal (>=)
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| NAnd -- ^ Logical and (&&)
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| NOr -- ^ Logical or (||)
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| NImpl -- ^ Logical implication (->)
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| NUpdate -- ^ Joining two attribut sets (//)
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| NPlus -- ^ Addition (+)
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| NMinus -- ^ Subtraction (-)
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| NMult -- ^ Multiplication (*)
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| NDiv -- ^ Division (/)
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| NConcat -- ^ List concatenation (++)
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deriving (Eq, Ord, Generic, Typeable, Data, Show)
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-- | Get the name out of the parameter (there might be none).
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paramName :: Params r -> Maybe Text
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paramName (Param n) = Just n
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paramName (ParamSet _ n) = n
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-- | Make an integer literal expression.
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mkInt :: Integer -> NExpr
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mkInt = Fix . NConstant . NInt
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-- | Make a regular (double-quoted) string.
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mkStr :: Text -> NExpr
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mkStr = Fix . NStr . DoubleQuoted . \case
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"" -> []
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x -> [Plain x]
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mkIndentedStr :: Text -> NExpr
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mkIndentedStr = Fix . NStr . Indented . \case
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"" -> []
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x -> [Plain x]
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-- | Make a literal URI expression.
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mkUri :: Text -> NExpr
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mkUri = Fix . NConstant . NUri
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-- | Make a path. Use 'True' if the path should be read from the
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-- environment, else 'False'.
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mkPath :: Bool -> FilePath -> NExpr
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mkPath False = Fix . NLiteralPath
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mkPath True = Fix . NEnvPath
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-- | Make a path expression which pulls from the NIX_PATH env variable.
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mkEnvPath :: FilePath -> NExpr
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mkEnvPath = mkPath True
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-- | Make a path expression which references a relative path.
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mkRelPath :: FilePath -> NExpr
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mkRelPath = mkPath False
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-- | Make a variable (symbol)
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mkSym :: Text -> NExpr
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mkSym = Fix . NSym
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mkSelector :: Text -> NAttrPath NExpr
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mkSelector = (:[]) . StaticKey
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mkBool :: Bool -> NExpr
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mkBool = Fix . NConstant . NBool
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mkNull :: NExpr
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mkNull = Fix (NConstant NNull)
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mkOper :: NUnaryOp -> NExpr -> NExpr
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mkOper op = Fix . NUnary op
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mkOper2 :: NBinaryOp -> NExpr -> NExpr -> NExpr
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mkOper2 op a = Fix . NBinary op a
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mkParamset :: [(Text, Maybe NExpr)] -> Params NExpr
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mkParamset params = ParamSet (mkFixedParamSet params) Nothing
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mkFixedParamSet :: [(Text, Maybe NExpr)] -> ParamSet NExpr
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mkFixedParamSet ps = FixedParamSet (Map.fromList ps)
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mkVariadicParamSet :: [(Text, Maybe NExpr)] -> ParamSet NExpr
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mkVariadicParamSet ps = VariadicParamSet (Map.fromList ps)
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mkApp :: NExpr -> NExpr -> NExpr
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mkApp e = Fix . NApp e
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mkRecSet :: [Binding NExpr] -> NExpr
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mkRecSet = Fix . NRecSet
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mkNonRecSet :: [Binding NExpr] -> NExpr
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mkNonRecSet = Fix . NSet
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mkLet :: [Binding NExpr] -> NExpr -> NExpr
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mkLet bs = Fix . NLet bs
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mkList :: [NExpr] -> NExpr
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mkList = Fix . NList
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mkWith :: NExpr -> NExpr -> NExpr
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mkWith e = Fix . NWith e
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mkAssert :: NExpr -> NExpr -> NExpr
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mkAssert e = Fix . NWith e
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mkIf :: NExpr -> NExpr -> NExpr -> NExpr
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mkIf e1 e2 = Fix . NIf e1 e2
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mkFunction :: Params NExpr -> NExpr -> NExpr
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mkFunction params = Fix . NAbs params
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-- | Shorthand for producing a binding of a name to an expression.
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bindTo :: Text -> NExpr -> Binding NExpr
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bindTo name val = NamedVar (mkSelector name) val
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|
||||||
-- | Append a list of bindings to a set or let expression.
|
|
||||||
-- For example, adding `[a = 1, b = 2]` to `let c = 3; in 4` produces
|
|
||||||
-- `let a = 1; b = 2; c = 3; in 4`.
|
|
||||||
appendBindings :: [Binding NExpr] -> NExpr -> NExpr
|
|
||||||
appendBindings newBindings (Fix e) = case e of
|
|
||||||
NLet bindings e' -> Fix $ NLet (bindings <> newBindings) e'
|
|
||||||
NSet bindings -> Fix $ NSet (bindings <> newBindings)
|
|
||||||
NRecSet bindings -> Fix $ NRecSet (bindings <> newBindings)
|
|
||||||
_ -> error "Can only append bindings to a set or a let"
|
|
||||||
|
|
||||||
-- | Applies a transformation to the body of a nix function.
|
|
||||||
modifyFunctionBody :: (NExpr -> NExpr) -> NExpr -> NExpr
|
|
||||||
modifyFunctionBody f (Fix e) = case e of
|
|
||||||
NAbs params body -> Fix $ NAbs params (f body)
|
|
||||||
_ -> error "Not a function"
|
|
||||||
|
|
||||||
|
import Nix.Expr.Types
|
||||||
|
import Nix.Expr.Shorthands
|
||||||
|
|
180
Nix/Expr/Shorthands.hs
Normal file
180
Nix/Expr/Shorthands.hs
Normal file
|
@ -0,0 +1,180 @@
|
||||||
|
-- | A bunch of shorthands for making nix expressions.
|
||||||
|
module Nix.Expr.Shorthands where
|
||||||
|
|
||||||
|
import Prelude
|
||||||
|
import Data.Monoid
|
||||||
|
import Data.Text (Text)
|
||||||
|
import Data.Fix
|
||||||
|
import qualified Data.Map as Map
|
||||||
|
import Nix.Atoms
|
||||||
|
import Nix.Expr.Types
|
||||||
|
|
||||||
|
-- | Make an integer literal expression.
|
||||||
|
mkInt :: Integer -> NExpr
|
||||||
|
mkInt = Fix . NConstant . NInt
|
||||||
|
|
||||||
|
-- | Make a regular (double-quoted) string.
|
||||||
|
mkStr :: Text -> NExpr
|
||||||
|
mkStr = Fix . NStr . DoubleQuoted . \case
|
||||||
|
"" -> []
|
||||||
|
x -> [Plain x]
|
||||||
|
|
||||||
|
mkIndentedStr :: Text -> NExpr
|
||||||
|
mkIndentedStr = Fix . NStr . Indented . \case
|
||||||
|
"" -> []
|
||||||
|
x -> [Plain x]
|
||||||
|
|
||||||
|
-- | Make a literal URI expression.
|
||||||
|
mkUri :: Text -> NExpr
|
||||||
|
mkUri = Fix . NConstant . NUri
|
||||||
|
|
||||||
|
-- | Make a path. Use 'True' if the path should be read from the
|
||||||
|
-- environment, else 'False'.
|
||||||
|
mkPath :: Bool -> FilePath -> NExpr
|
||||||
|
mkPath False = Fix . NLiteralPath
|
||||||
|
mkPath True = Fix . NEnvPath
|
||||||
|
|
||||||
|
-- | Make a path expression which pulls from the NIX_PATH env variable.
|
||||||
|
mkEnvPath :: FilePath -> NExpr
|
||||||
|
mkEnvPath = mkPath True
|
||||||
|
|
||||||
|
-- | Make a path expression which references a relative path.
|
||||||
|
mkRelPath :: FilePath -> NExpr
|
||||||
|
mkRelPath = mkPath False
|
||||||
|
|
||||||
|
-- | Make a variable (symbol)
|
||||||
|
mkSym :: Text -> NExpr
|
||||||
|
mkSym = Fix . NSym
|
||||||
|
|
||||||
|
mkSelector :: Text -> NAttrPath NExpr
|
||||||
|
mkSelector = (:[]) . StaticKey
|
||||||
|
|
||||||
|
mkBool :: Bool -> NExpr
|
||||||
|
mkBool = Fix . NConstant . NBool
|
||||||
|
|
||||||
|
mkNull :: NExpr
|
||||||
|
mkNull = Fix (NConstant NNull)
|
||||||
|
|
||||||
|
mkOper :: NUnaryOp -> NExpr -> NExpr
|
||||||
|
mkOper op = Fix . NUnary op
|
||||||
|
|
||||||
|
mkOper2 :: NBinaryOp -> NExpr -> NExpr -> NExpr
|
||||||
|
mkOper2 op a = Fix . NBinary op a
|
||||||
|
|
||||||
|
mkParamset :: [(Text, Maybe NExpr)] -> Params NExpr
|
||||||
|
mkParamset params = ParamSet (mkFixedParamSet params) Nothing
|
||||||
|
|
||||||
|
mkFixedParamSet :: [(Text, Maybe NExpr)] -> ParamSet NExpr
|
||||||
|
mkFixedParamSet ps = FixedParamSet (Map.fromList ps)
|
||||||
|
|
||||||
|
mkVariadicParamSet :: [(Text, Maybe NExpr)] -> ParamSet NExpr
|
||||||
|
mkVariadicParamSet ps = VariadicParamSet (Map.fromList ps)
|
||||||
|
|
||||||
|
mkApp :: NExpr -> NExpr -> NExpr
|
||||||
|
mkApp e = Fix . NApp e
|
||||||
|
|
||||||
|
mkRecSet :: [Binding NExpr] -> NExpr
|
||||||
|
mkRecSet = Fix . NRecSet
|
||||||
|
|
||||||
|
mkNonRecSet :: [Binding NExpr] -> NExpr
|
||||||
|
mkNonRecSet = Fix . NSet
|
||||||
|
|
||||||
|
mkLets :: [Binding NExpr] -> NExpr -> NExpr
|
||||||
|
mkLets bindings = Fix . NLet bindings
|
||||||
|
|
||||||
|
mkList :: [NExpr] -> NExpr
|
||||||
|
mkList = Fix . NList
|
||||||
|
|
||||||
|
mkWith :: NExpr -> NExpr -> NExpr
|
||||||
|
mkWith e = Fix . NWith e
|
||||||
|
|
||||||
|
mkAssert :: NExpr -> NExpr -> NExpr
|
||||||
|
mkAssert e = Fix . NWith e
|
||||||
|
|
||||||
|
mkIf :: NExpr -> NExpr -> NExpr -> NExpr
|
||||||
|
mkIf e1 e2 = Fix . NIf e1 e2
|
||||||
|
|
||||||
|
mkFunction :: Params NExpr -> NExpr -> NExpr
|
||||||
|
mkFunction params = Fix . NAbs params
|
||||||
|
|
||||||
|
mkDot :: NExpr -> Text -> NExpr
|
||||||
|
mkDot e key = Fix $ NSelect e [StaticKey key] Nothing
|
||||||
|
|
||||||
|
-- | Shorthand for producing a binding of a name to an expression.
|
||||||
|
bindTo :: Text -> NExpr -> Binding NExpr
|
||||||
|
bindTo name val = NamedVar (mkSelector name) val
|
||||||
|
|
||||||
|
-- | Append a list of bindings to a set or let expression.
|
||||||
|
-- For example, adding `[a = 1, b = 2]` to `let c = 3; in 4` produces
|
||||||
|
-- `let a = 1; b = 2; c = 3; in 4`.
|
||||||
|
appendBindings :: [Binding NExpr] -> NExpr -> NExpr
|
||||||
|
appendBindings newBindings (Fix e) = case e of
|
||||||
|
NLet bindings e' -> Fix $ NLet (bindings <> newBindings) e'
|
||||||
|
NSet bindings -> Fix $ NSet (bindings <> newBindings)
|
||||||
|
NRecSet bindings -> Fix $ NRecSet (bindings <> newBindings)
|
||||||
|
_ -> error "Can only append bindings to a set or a let"
|
||||||
|
|
||||||
|
-- | Applies a transformation to the body of a nix function.
|
||||||
|
modifyFunctionBody :: (NExpr -> NExpr) -> NExpr -> NExpr
|
||||||
|
modifyFunctionBody f (Fix e) = case e of
|
||||||
|
NAbs params body -> Fix $ NAbs params (f body)
|
||||||
|
_ -> error "Not a function"
|
||||||
|
|
||||||
|
-- | A let statement with multiple assignments.
|
||||||
|
letsE :: [(Text, NExpr)] -> NExpr -> NExpr
|
||||||
|
letsE pairs = Fix . NLet (map (uncurry bindTo) pairs)
|
||||||
|
|
||||||
|
-- | Wrapper for a single-variable @let@.
|
||||||
|
letE :: Text -> NExpr -> NExpr -> NExpr
|
||||||
|
letE varName varExpr = letsE [(varName, varExpr)]
|
||||||
|
|
||||||
|
-- | Make an attribute set (non-recursive).
|
||||||
|
attrsE :: [(Text, NExpr)] -> NExpr
|
||||||
|
attrsE pairs = Fix $ NSet (map (uncurry bindTo) pairs)
|
||||||
|
|
||||||
|
-- | Make an attribute set (recursive).
|
||||||
|
recAttrsE :: [(Text, NExpr)] -> NExpr
|
||||||
|
recAttrsE pairs = Fix $ NRecSet (map (uncurry bindTo) pairs)
|
||||||
|
|
||||||
|
-- | Logical negation.
|
||||||
|
mkNot :: NExpr -> NExpr
|
||||||
|
mkNot = Fix . NUnary NNot
|
||||||
|
|
||||||
|
-- | Dot-reference into an attribute set.
|
||||||
|
(!.) :: NExpr -> Text -> NExpr
|
||||||
|
(!.) = mkDot
|
||||||
|
infixl 8 !.
|
||||||
|
|
||||||
|
mkBinop :: NBinaryOp -> NExpr -> NExpr -> NExpr
|
||||||
|
mkBinop op e1 e2 = Fix (NBinary op e1 e2)
|
||||||
|
|
||||||
|
-- | Various nix binary operators
|
||||||
|
($==), ($!=), ($<), ($<=), ($>), ($>=), ($&&), ($||), ($->),
|
||||||
|
($//), ($+), ($-), ($*), ($/), ($++)
|
||||||
|
:: NExpr -> NExpr -> NExpr
|
||||||
|
e1 $== e2 = mkBinop NEq e1 e2
|
||||||
|
e1 $!= e2 = mkBinop NNEq e1 e2
|
||||||
|
e1 $< e2 = mkBinop NLt e1 e2
|
||||||
|
e1 $<= e2 = mkBinop NLte e1 e2
|
||||||
|
e1 $> e2 = mkBinop NGt e1 e2
|
||||||
|
e1 $>= e2 = mkBinop NGte e1 e2
|
||||||
|
e1 $&& e2 = mkBinop NAnd e1 e2
|
||||||
|
e1 $|| e2 = mkBinop NOr e1 e2
|
||||||
|
e1 $-> e2 = mkBinop NImpl e1 e2
|
||||||
|
e1 $// e2 = mkBinop NUpdate e1 e2
|
||||||
|
e1 $+ e2 = mkBinop NPlus e1 e2
|
||||||
|
e1 $- e2 = mkBinop NMinus e1 e2
|
||||||
|
e1 $* e2 = mkBinop NMult e1 e2
|
||||||
|
e1 $/ e2 = mkBinop NDiv e1 e2
|
||||||
|
e1 $++ e2 = mkBinop NConcat e1 e2
|
||||||
|
|
||||||
|
-- | Function application expression.
|
||||||
|
(@@) :: NExpr -> NExpr -> NExpr
|
||||||
|
(@@) = mkApp
|
||||||
|
infixl 1 @@
|
||||||
|
|
||||||
|
-- | Lambda shorthand.
|
||||||
|
(==>) :: Params NExpr -> NExpr -> NExpr
|
||||||
|
(==>) = mkFunction
|
||||||
|
|
||||||
|
infixr 1 ==>
|
193
Nix/Expr/Types.hs
Normal file
193
Nix/Expr/Types.hs
Normal file
|
@ -0,0 +1,193 @@
|
||||||
|
{-# LANGUAGE FlexibleInstances #-}
|
||||||
|
{-# LANGUAGE DeriveTraversable #-}
|
||||||
|
{-# LANGUAGE DeriveFoldable #-}
|
||||||
|
{-# LANGUAGE DeriveGeneric #-}
|
||||||
|
{-# LANGUAGE DeriveDataTypeable #-}
|
||||||
|
{-# LANGUAGE DeriveFunctor #-}
|
||||||
|
{-# LANGUAGE OverloadedStrings #-}
|
||||||
|
{-# LANGUAGE LambdaCase #-}
|
||||||
|
-- | The nix expression type and supporting types.
|
||||||
|
module Nix.Expr.Types where
|
||||||
|
|
||||||
|
import Control.Monad hiding (forM_, mapM, sequence)
|
||||||
|
import Data.Data
|
||||||
|
import Data.Fix
|
||||||
|
import Data.Foldable
|
||||||
|
import Data.Map (Map)
|
||||||
|
import Data.Text (Text, pack)
|
||||||
|
import Data.Traversable
|
||||||
|
import GHC.Exts
|
||||||
|
import GHC.Generics
|
||||||
|
import Nix.Atoms
|
||||||
|
import Prelude hiding (readFile, concat, concatMap, elem, mapM,
|
||||||
|
sequence, minimum, foldr)
|
||||||
|
|
||||||
|
-- | The main nix expression type. This is polymorphic so that it can be made
|
||||||
|
-- a functor, which allows us to traverse expressions and map functions over
|
||||||
|
-- them. The actual 'NExpr' type is a fixed point of this functor, defined
|
||||||
|
-- below.
|
||||||
|
data NExprF r
|
||||||
|
= NConstant !NAtom
|
||||||
|
-- ^ Constants: ints, bools, URIs, and null.
|
||||||
|
| NStr !(NString r)
|
||||||
|
-- ^ A string, with interpolated expressions.
|
||||||
|
| NSym !Text
|
||||||
|
-- ^ A variable. For example, in the expression @f a@, @f@ is represented
|
||||||
|
-- as @NSym "f"@ and @a@ as @NSym "a"@.
|
||||||
|
| NList ![r]
|
||||||
|
-- ^ A list literal.
|
||||||
|
| NSet ![Binding r]
|
||||||
|
-- ^ An attribute set literal, not recursive.
|
||||||
|
| NRecSet ![Binding r]
|
||||||
|
-- ^ An attribute set literal, recursive.
|
||||||
|
| NLiteralPath !FilePath
|
||||||
|
-- ^ A path expression, which is evaluated to a store path. The path here
|
||||||
|
-- can be relative, in which case it's evaluated relative to the file in
|
||||||
|
-- which it appears.
|
||||||
|
| NEnvPath !FilePath
|
||||||
|
-- ^ A path which refers to something in the Nix search path (the NIX_PATH
|
||||||
|
-- environment variable. For example, @<nixpkgs/pkgs>@.
|
||||||
|
| NUnary !NUnaryOp !r
|
||||||
|
-- ^ Application of a unary operator to an expression.
|
||||||
|
| NBinary !NBinaryOp !r !r
|
||||||
|
-- ^ Application of a binary operator to two expressions.
|
||||||
|
| NSelect !r !(NAttrPath r) !(Maybe r)
|
||||||
|
-- ^ Dot-reference into an attribute set, optionally providing an
|
||||||
|
-- alternative if the key doesn't exist.
|
||||||
|
| NHasAttr !r !(NAttrPath r)
|
||||||
|
-- ^ Ask if a set contains a given attribute path.
|
||||||
|
| NAbs !(Params r) !r
|
||||||
|
-- ^ A function literal (lambda abstraction).
|
||||||
|
| NApp !r !r
|
||||||
|
-- ^ Apply a function to an argument.
|
||||||
|
| NLet ![Binding r] !r
|
||||||
|
-- ^ Evaluate the second argument after introducing the bindings.
|
||||||
|
| NIf !r !r !r
|
||||||
|
-- ^ If-then-else statement.
|
||||||
|
| NWith !r !r
|
||||||
|
-- ^ Evaluate an attribute set, bring its bindings into scope, and
|
||||||
|
-- evaluate the second argument.
|
||||||
|
| NAssert !r !r
|
||||||
|
-- ^ Assert that the first returns true before evaluating the second.
|
||||||
|
deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show)
|
||||||
|
|
||||||
|
-- | The monomorphic expression type is a fixed point of the polymorphic one.
|
||||||
|
type NExpr = Fix NExprF
|
||||||
|
|
||||||
|
-- | A single line of the bindings section of a let expression or of a set.
|
||||||
|
data Binding r
|
||||||
|
= NamedVar !(NAttrPath r) !r
|
||||||
|
-- ^ An explicit naming, such as @x = y@ or @x.y = z@.
|
||||||
|
| Inherit !(Maybe r) ![NKeyName r]
|
||||||
|
-- ^ Using a name already in scope, such as @inherit x;@ which is shorthand
|
||||||
|
-- for @x = x;@ or @inherit (x) y;@ which means @y = x.y;@.
|
||||||
|
deriving (Typeable, Data, Ord, Eq, Functor, Show)
|
||||||
|
|
||||||
|
-- | @Params@ represents all the ways the formal parameters to a
|
||||||
|
-- function can be represented.
|
||||||
|
data Params r
|
||||||
|
= Param !Text
|
||||||
|
-- ^ For functions with a single named argument, such as @x: x + 1@.
|
||||||
|
| ParamSet !(ParamSet r) !(Maybe Text)
|
||||||
|
-- ^ Explicit parameters (argument must be a set). Might specify a name
|
||||||
|
-- to bind to the set in the function body.
|
||||||
|
deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show,
|
||||||
|
Foldable, Traversable)
|
||||||
|
|
||||||
|
instance IsString (Params r) where
|
||||||
|
fromString = Param . fromString
|
||||||
|
|
||||||
|
-- | An explicit parameter set; provides a shorthand for unpacking arguments.
|
||||||
|
data ParamSet r
|
||||||
|
= FixedParamSet !(Map Text (Maybe r))
|
||||||
|
-- ^ A fixed set, where no arguments beyond what is specified in the map
|
||||||
|
-- may be given. The map might contain defaults for arguments not passed.
|
||||||
|
| VariadicParamSet !(Map Text (Maybe r))
|
||||||
|
-- ^ Same as the 'FixedParamSet', but extra arguments are allowed.
|
||||||
|
deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show,
|
||||||
|
Foldable, Traversable)
|
||||||
|
|
||||||
|
-- | 'Antiquoted' represents an expression that is either
|
||||||
|
-- antiquoted (surrounded by ${...}) or plain (not antiquoted).
|
||||||
|
data Antiquoted v r = Plain !v | Antiquoted !r
|
||||||
|
deriving (Ord, Eq, Generic, Typeable, Data, Functor, Show)
|
||||||
|
|
||||||
|
-- | An 'NString' is a list of things that are either a plain string
|
||||||
|
-- or an antiquoted expression. After the antiquotes have been evaluated,
|
||||||
|
-- the final string is constructed by concating all the parts.
|
||||||
|
data NString r
|
||||||
|
= DoubleQuoted ![Antiquoted Text r]
|
||||||
|
-- ^ Strings wrapped with double-quotes (") are not allowed to contain
|
||||||
|
-- literal newline characters.
|
||||||
|
| Indented ![Antiquoted Text r]
|
||||||
|
-- ^ Strings wrapped with two single quotes ('') can contain newlines,
|
||||||
|
-- and their indentation will be stripped.
|
||||||
|
deriving (Eq, Ord, Generic, Typeable, Data, Functor, Show)
|
||||||
|
|
||||||
|
-- | For the the 'IsString' instance, we use a plain doublequoted string.
|
||||||
|
instance IsString (NString r) where
|
||||||
|
fromString "" = DoubleQuoted []
|
||||||
|
fromString string = DoubleQuoted [Plain $ pack string]
|
||||||
|
|
||||||
|
-- | A 'KeyName' is something that can appear at the right side of an
|
||||||
|
-- equals sign. For example, @a@ is a 'KeyName' in @{ a = 3; }@, @let a = 3;
|
||||||
|
-- in ...@, @{}.a@ or @{} ? a@.
|
||||||
|
--
|
||||||
|
-- Nix supports both static keynames (just an identifier) and dynamic
|
||||||
|
-- identifiers. Dynamic identifiers can be either a string (e.g.:
|
||||||
|
-- @{ "a" = 3; }@) or an antiquotation (e.g.: @let a = "example";
|
||||||
|
-- in { ${a} = 3; }.example@).
|
||||||
|
--
|
||||||
|
-- Note: There are some places where a dynamic keyname is not allowed.
|
||||||
|
-- In particular, those include:
|
||||||
|
--
|
||||||
|
-- * The RHS of a @binding@ inside @let@: @let ${"a"} = 3; in ...@
|
||||||
|
-- produces a syntax error.
|
||||||
|
-- * The attribute names of an 'inherit': @inherit ${"a"};@ is forbidden.
|
||||||
|
--
|
||||||
|
-- Note: In Nix, a simple string without antiquotes such as @"foo"@ is
|
||||||
|
-- allowed even if the context requires a static keyname, but the
|
||||||
|
-- parser still considers it a 'DynamicKey' for simplicity.
|
||||||
|
data NKeyName r
|
||||||
|
= DynamicKey !(Antiquoted (NString r) r)
|
||||||
|
| StaticKey !Text
|
||||||
|
deriving (Eq, Ord, Generic, Typeable, Data, Show)
|
||||||
|
|
||||||
|
-- | Deriving this instance automatically is not possible because @r@
|
||||||
|
-- occurs not only as last argument in @Antiquoted (NString r) r@
|
||||||
|
instance Functor NKeyName where
|
||||||
|
fmap f (DynamicKey (Plain str)) = DynamicKey . Plain $ fmap f str
|
||||||
|
fmap f (DynamicKey (Antiquoted e)) = DynamicKey . Antiquoted $ f e
|
||||||
|
fmap _ (StaticKey key) = StaticKey key
|
||||||
|
|
||||||
|
-- | A selector (for example in a @let@ or an attribute set) is made up
|
||||||
|
-- of strung-together key names.
|
||||||
|
type NAttrPath r = [NKeyName r]
|
||||||
|
|
||||||
|
-- | There are two unary operations: logical not and integer negation.
|
||||||
|
data NUnaryOp = NNeg | NNot
|
||||||
|
deriving (Eq, Ord, Generic, Typeable, Data, Show)
|
||||||
|
|
||||||
|
-- | Binary operators expressible in the nix language.
|
||||||
|
data NBinaryOp
|
||||||
|
= NEq -- ^ Equality (==)
|
||||||
|
| NNEq -- ^ Inequality (!=)
|
||||||
|
| NLt -- ^ Less than (<)
|
||||||
|
| NLte -- ^ Less than or equal (<=)
|
||||||
|
| NGt -- ^ Greater than (>)
|
||||||
|
| NGte -- ^ Greater than or equal (>=)
|
||||||
|
| NAnd -- ^ Logical and (&&)
|
||||||
|
| NOr -- ^ Logical or (||)
|
||||||
|
| NImpl -- ^ Logical implication (->)
|
||||||
|
| NUpdate -- ^ Joining two attribut sets (//)
|
||||||
|
| NPlus -- ^ Addition (+)
|
||||||
|
| NMinus -- ^ Subtraction (-)
|
||||||
|
| NMult -- ^ Multiplication (*)
|
||||||
|
| NDiv -- ^ Division (/)
|
||||||
|
| NConcat -- ^ List concatenation (++)
|
||||||
|
deriving (Eq, Ord, Generic, Typeable, Data, Show)
|
||||||
|
|
||||||
|
-- | Get the name out of the parameter (there might be none).
|
||||||
|
paramName :: Params r -> Maybe Text
|
||||||
|
paramName (Param n) = Just n
|
||||||
|
paramName (ParamSet _ n) = n
|
|
@ -7,6 +7,7 @@ import Data.Map (toList)
|
||||||
import Data.Maybe (isJust)
|
import Data.Maybe (isJust)
|
||||||
import Data.Text (Text, pack, unpack, replace, strip)
|
import Data.Text (Text, pack, unpack, replace, strip)
|
||||||
import Data.List (isPrefixOf)
|
import Data.List (isPrefixOf)
|
||||||
|
import Nix.Atoms
|
||||||
import Nix.Expr
|
import Nix.Expr
|
||||||
import Nix.Parser.Library (reservedNames)
|
import Nix.Parser.Library (reservedNames)
|
||||||
import Nix.Parser.Operators
|
import Nix.Parser.Operators
|
||||||
|
|
|
@ -22,6 +22,7 @@ Flag Parsec
|
||||||
Library
|
Library
|
||||||
Default-language: Haskell2010
|
Default-language: Haskell2010
|
||||||
Exposed-modules:
|
Exposed-modules:
|
||||||
|
Nix.Atoms
|
||||||
Nix.Eval
|
Nix.Eval
|
||||||
Nix.Parser
|
Nix.Parser
|
||||||
Nix.Expr
|
Nix.Expr
|
||||||
|
@ -30,6 +31,8 @@ Library
|
||||||
Nix.StringOperations
|
Nix.StringOperations
|
||||||
Other-modules:
|
Other-modules:
|
||||||
Nix.Parser.Library
|
Nix.Parser.Library
|
||||||
|
Nix.Expr.Types
|
||||||
|
Nix.Expr.Shorthands
|
||||||
Default-extensions:
|
Default-extensions:
|
||||||
DataKinds
|
DataKinds
|
||||||
DeriveDataTypeable
|
DeriveDataTypeable
|
||||||
|
|
|
@ -10,6 +10,7 @@ import Test.Tasty.TH
|
||||||
|
|
||||||
import qualified Data.Map as Map
|
import qualified Data.Map as Map
|
||||||
|
|
||||||
|
import Nix.Atoms
|
||||||
import Nix.Expr
|
import Nix.Expr
|
||||||
import Nix.Parser
|
import Nix.Parser
|
||||||
import Nix.StringOperations
|
import Nix.StringOperations
|
||||||
|
|
Loading…
Reference in a new issue