summaryrefslogtreecommitdiff
path: root/dhall/src/semantics/phase/mod.rs
blob: 5332eb39e0384908270b0216c160f49b0a8930cf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
use std::fmt::Display;
use std::path::Path;

use crate::error::{EncodeError, Error, ImportError, TypeError};
use crate::semantics::core::value::Value;
use crate::semantics::core::value::ValueKind;
use crate::semantics::core::var::{AlphaVar, Shift, Subst};
use crate::semantics::to_expr::ToExprOptions;
use crate::syntax::binary;
use crate::syntax::{Builtin, Const, Expr};
use resolve::ImportRoot;

pub(crate) mod normalize;
pub(crate) mod parse;
pub(crate) mod resolve;
pub(crate) mod typecheck;

pub type ParsedExpr = Expr<Normalized>;
pub type DecodedExpr = Expr<Normalized>;
pub type ResolvedExpr = Expr<Normalized>;
pub type NormalizedExpr = Expr<Normalized>;

#[derive(Debug, Clone)]
pub struct Parsed(ParsedExpr, ImportRoot);

/// An expression where all imports have been resolved
///
/// Invariant: there must be no `Import` nodes or `ImportAlt` operations left.
#[derive(Debug, Clone)]
pub struct Resolved(ResolvedExpr);

/// A typed expression
#[derive(Debug, Clone)]
pub struct Typed(Value);

/// A normalized expression.
///
/// Invariant: the contained Typed expression must be in normal form,
#[derive(Debug, Clone)]
pub struct Normalized(Typed);

impl Parsed {
    pub fn parse_file(f: &Path) -> Result<Parsed, Error> {
        parse::parse_file(f)
    }
    pub fn parse_str(s: &str) -> Result<Parsed, Error> {
        parse::parse_str(s)
    }
    pub fn parse_binary_file(f: &Path) -> Result<Parsed, Error> {
        parse::parse_binary_file(f)
    }
    pub fn parse_binary(data: &[u8]) -> Result<Parsed, Error> {
        parse::parse_binary(data)
    }

    pub fn resolve(self) -> Result<Resolved, ImportError> {
        resolve::resolve(self)
    }
    pub fn skip_resolve(self) -> Result<Resolved, ImportError> {
        resolve::skip_resolve_expr(self)
    }

    pub fn encode(&self) -> Result<Vec<u8>, EncodeError> {
        binary::encode(&self.0)
    }

    /// Converts a value back to the corresponding AST expression.
    pub fn to_expr(&self) -> ParsedExpr {
        self.0.clone()
    }
}

impl Resolved {
    pub fn typecheck(self) -> Result<Typed, TypeError> {
        Ok(typecheck::typecheck(self.0)?.into_typed())
    }
    pub fn typecheck_with(self, ty: &Typed) -> Result<Typed, TypeError> {
        Ok(typecheck::typecheck_with(self.0, ty.normalize_to_expr())?
            .into_typed())
    }
    /// Converts a value back to the corresponding AST expression.
    pub fn to_expr(&self) -> ResolvedExpr {
        self.0.clone()
    }
}

impl Typed {
    /// Reduce an expression to its normal form, performing beta reduction
    pub fn normalize(mut self) -> Normalized {
        self.normalize_mut();
        Normalized(self)
    }

    pub(crate) fn from_const(c: Const) -> Self {
        Typed(Value::from_const(c))
    }
    pub(crate) fn from_kind_and_type(v: ValueKind, t: Typed) -> Self {
        Typed(Value::from_kind_and_type(v, t.into_value()))
    }
    pub(crate) fn from_value(th: Value) -> Self {
        Typed(th)
    }
    pub(crate) fn const_type() -> Self {
        Typed::from_const(Const::Type)
    }

    /// Converts a value back to the corresponding AST expression.
    pub fn to_expr(&self) -> ResolvedExpr {
        self.0.to_expr(ToExprOptions {
            alpha: false,
            normalize: false,
        })
    }
    /// Converts a value back to the corresponding AST expression, beta-normalizing in the process.
    pub fn normalize_to_expr(&self) -> NormalizedExpr {
        self.0.to_expr(ToExprOptions {
            alpha: false,
            normalize: true,
        })
    }
    /// Converts a value back to the corresponding AST expression, (alpha,beta)-normalizing in the
    /// process.
    pub(crate) fn normalize_to_expr_alpha(&self) -> NormalizedExpr {
        self.0.to_expr(ToExprOptions {
            alpha: true,
            normalize: true,
        })
    }
    pub(crate) fn to_value(&self) -> Value {
        self.0.clone()
    }
    pub(crate) fn into_value(self) -> Value {
        self.0
    }

    pub(crate) fn normalize_mut(&mut self) {
        self.0.normalize_mut()
    }

    pub(crate) fn get_type(&self) -> Result<Typed, TypeError> {
        Ok(self.0.get_type()?.into_typed())
    }

    pub fn make_builtin_type(b: Builtin) -> Self {
        Typed::from_value(Value::from_builtin(b))
    }
    pub fn make_optional_type(t: Typed) -> Self {
        Typed::from_value(
            Value::from_builtin(Builtin::Optional).app(t.to_value()),
        )
    }
    pub fn make_list_type(t: Typed) -> Self {
        Typed::from_value(Value::from_builtin(Builtin::List).app(t.to_value()))
    }
    pub fn make_record_type(
        kts: impl Iterator<Item = (String, Typed)>,
    ) -> Self {
        Typed::from_kind_and_type(
            ValueKind::RecordType(
                kts.map(|(k, t)| (k.into(), t.into_value())).collect(),
            ),
            Typed::const_type(),
        )
    }
    pub fn make_union_type(
        kts: impl Iterator<Item = (String, Option<Typed>)>,
    ) -> Self {
        Typed::from_kind_and_type(
            ValueKind::UnionType(
                kts.map(|(k, t)| (k.into(), t.map(|t| t.into_value())))
                    .collect(),
            ),
            Typed::const_type(),
        )
    }
}

impl Normalized {
    pub fn encode(&self) -> Result<Vec<u8>, EncodeError> {
        binary::encode(&self.to_expr())
    }

    pub(crate) fn to_expr(&self) -> NormalizedExpr {
        self.0.normalize_to_expr()
    }
    pub(crate) fn to_expr_alpha(&self) -> NormalizedExpr {
        self.0.normalize_to_expr_alpha()
    }
    pub(crate) fn into_typed(self) -> Typed {
        self.0
    }
}

impl Shift for Typed {
    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
        Some(Typed(self.0.shift(delta, var)?))
    }
}

impl Shift for Normalized {
    fn shift(&self, delta: isize, var: &AlphaVar) -> Option<Self> {
        Some(Normalized(self.0.shift(delta, var)?))
    }
}

impl Subst<Value> for Typed {
    fn subst_shift(&self, var: &AlphaVar, val: &Value) -> Self {
        Typed(self.0.subst_shift(var, val))
    }
}

macro_rules! derive_traits_for_wrapper_struct {
    ($ty:ident) => {
        impl std::cmp::PartialEq for $ty {
            fn eq(&self, other: &Self) -> bool {
                self.0 == other.0
            }
        }

        impl std::cmp::Eq for $ty {}

        impl std::fmt::Display for $ty {
            fn fmt(
                &self,
                f: &mut std::fmt::Formatter,
            ) -> Result<(), std::fmt::Error> {
                self.0.fmt(f)
            }
        }
    };
}

derive_traits_for_wrapper_struct!(Parsed);
derive_traits_for_wrapper_struct!(Resolved);
derive_traits_for_wrapper_struct!(Normalized);

impl std::hash::Hash for Normalized {
    fn hash<H>(&self, state: &mut H)
    where
        H: std::hash::Hasher,
    {
        if let Ok(vec) = self.encode() {
            vec.hash(state)
        }
    }
}

impl Eq for Typed {}
impl PartialEq for Typed {
    fn eq(&self, other: &Self) -> bool {
        self.0 == other.0
    }
}

impl Display for Typed {
    fn fmt(&self, f: &mut std::fmt::Formatter) -> Result<(), std::fmt::Error> {
        self.to_expr().fmt(f)
    }
}