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use std::collections::HashMap;
use std::path::PathBuf;
/*
module Dhall.Core (
-- * Syntax
Const(..)
, Path(..)
, Var(..)
, Expr(..)
-- * Normalization
, normalize
, subst
, shift
-- * Pretty-printing
, pretty
-- * Miscellaneous
, internalError
) where
*/
/// Constants for a pure type system
///
/// The only axiom is:
///
/// ```c
/// ⊦ Type : Kind
/// ```
///
/// ... and the valid rule pairs are:
///
/// ```c
/// ⊦ Type ↝ Type : Type -- Functions from terms to terms (ordinary functions)
/// ⊦ Kind ↝ Type : Type -- Functions from types to terms (polymorphic functions)
/// ⊦ Kind ↝ Kind : Kind -- Functions from types to types (type constructors)
/// ```
///
/// These are the same rule pairs as System Fω
///
/// Note that Dhall does not support functions from terms to types and therefore
/// Dhall is not a dependently typed language
///
#[derive(Debug, PartialEq, Eq)] // (Show, Bounded, Enum)
pub enum Const {
Type,
Kind,
}
/// Path to an external resource
#[derive(Debug, PartialEq, Eq)] // (Eq, Ord, Show)
pub enum Path {
File(PathBuf),
URL(String),
}
/// Label for a bound variable
///
/// The `String` field is the variable's name (i.e. \"`x`\").
///
/// The `Int` field disambiguates variables with the same name if there are
/// multiple bound variables of the same name in scope. Zero refers to the
/// nearest bound variable and the index increases by one for each bound
/// variable of the same name going outward. The following diagram may help:
///
/// ```c
/// +---refers to--+
/// | |
/// v |
/// \(x : Type) -> \(y : Type) -> \(x : Type) -> x@0
///
/// +------------------refers to-----------------+
/// | |
/// v |
/// \(x : Type) -> \(y : Type) -> \(x : Type) -> x@1
/// ```
///
/// This `Int` behaves like a De Bruijn index in the special case where all
/// variables have the same name.
///
/// You can optionally omit the index if it is `0`:
///
/// ```c
/// +refers to+
/// | |
/// v |
/// \(x : *) -> \(y : *) -> \(x : *) -> x
/// ```
///
/// Zero indices are omitted when pretty-printing `Var`s and non-zero indices
/// appear as a numeric suffix.
///
#[derive(Debug, PartialEq, Eq)] // (Eq, Show)
pub struct Var(pub String, pub Int);
/*
instance IsString Var where
fromString str = V (fromString str) 0
instance Buildable Var where
build = buildVar
*/
/// Syntax tree for expressions
#[derive(Debug, PartialEq)] // (Functor, Foldable, Traversable, Show)
pub enum Expr<S, A> {
/// `Const c ~ c`
Const(Const),
/// `Var (V x 0) ~ x`<br>
/// `Var (V x n) ~ x@n`
Var(Var),
/// `Lam x A b ~ λ(x : A) -> b`
Lam(String, Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Pi "_" A B ~ A -> B`
/// `Pi x A B ~ ∀(x : A) -> B`
Pi(String, Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `App f A ~ f A`
App(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Let x Nothing r e ~ let x = r in e`
/// `Let x (Just t) r e ~ let x : t = r in e`
Let(String, Option<Box<Expr<S, A>>>, Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Annot x t ~ x : t`
Annot(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Bool ~ Bool`
Bool,
/// `BoolLit b ~ b`
BoolLit(bool),
/// `BoolAnd x y ~ x && y`
BoolAnd(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `BoolOr x y ~ x || y`
BoolOr(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `BoolEQ x y ~ x == y`
BoolEQ(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `BoolNE x y ~ x != y`
BoolNE(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `BoolIf x y z ~ if x then y else z`
BoolIf(Box<Expr<S, A>>, Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Natural ~ Natural`
Natural,
/// `NaturalLit n ~ +n`
NaturalLit(Natural),
/// `NaturalFold ~ Natural/fold`
NaturalFold,
/// `NaturalBuild ~ Natural/build`
NaturalBuild,
/// `NaturalIsZero ~ Natural/isZero`
NaturalIsZero,
/// `NaturalEven ~ Natural/even`
NaturalEven,
/// `NaturalOdd ~ Natural/odd`
NaturalOdd,
/// `NaturalPlus x y ~ x + y`
NaturalPlus(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `NaturalTimes x y ~ x * y`
NaturalTimes(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Integer ~ Integer`
Integer,
/// `IntegerLit n ~ n`
IntegerLit(Integer),
/// `Double ~ Double`
Double,
/// `DoubleLit n ~ n`
DoubleLit(Double),
/// `Text ~ Text`
Text,
/// `TextLit t ~ t`
TextLit(Builder),
/// `TextAppend x y ~ x ++ y`
TextAppend(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `List ~ List`
List,
/// `ListLit t [x, y, z] ~ [x, y, z] : List t`
ListLit(Box<Expr<S, A>>, Vec<Expr<S, A>>),
/// `ListBuild ~ List/build`
ListBuild,
/// `ListFold ~ List/fold`
ListFold,
/// `ListLength ~ List/length`
ListLength,
/// `ListHead ~ List/head`
ListHead,
/// `ListLast ~ List/last`
ListLast,
/// `ListIndexed ~ List/indexed`
ListIndexed,
/// `ListReverse ~ List/reverse`
ListReverse,
/// `Optional ~ Optional`
Optional,
/// `OptionalLit t [e] ~ [e] : Optional t`
/// `OptionalLit t [] ~ [] : Optional t`
OptionalLit(Box<Expr<S, A>>, Vec<Expr<S, A>>),
/// `OptionalFold ~ Optional/fold`
OptionalFold,
/// `Record [(k1, t1), (k2, t2)] ~ { k1 : t1, k2 : t1 }`
Record(HashMap<String, Expr<S, A>>),
/// `RecordLit [(k1, v1), (k2, v2)] ~ { k1 = v1, k2 = v2 }`
RecordLit(HashMap<String, Expr<S, A>>),
/// `Union [(k1, t1), (k2, t2)] ~ < k1 : t1, k2 : t2 >`
Union(HashMap<String, Expr<S, A>>),
/// `UnionLit (k1, v1) [(k2, t2), (k3, t3)] ~ < k1 = t1, k2 : t2, k3 : t3 >`
UnionLit(String, Box<Expr<S, A>>, HashMap<String, Expr<S, A>>),
/// `Combine x y ~ x ∧ y`
Combine(Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Merge x y t ~ merge x y : t`
Merge(Box<Expr<S, A>>, Box<Expr<S, A>>, Box<Expr<S, A>>),
/// `Field e x ~ e.x`
Field(Box<Expr<S, A>>, String),
/// `Note S x ~ e`
Note(S, Box<Expr<S, A>>),
/// `Embed path ~ path`
Embed(A),
}
pub type Builder = String;
pub type Double = f64;
pub type Int = isize;
pub type Integer = isize;
pub type Natural = usize;
|
