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authorNadrieril2020-09-14 23:09:22 +0100
committerNadrieril2020-09-14 23:19:49 +0100
commit7e523ae1903ae2d8bca8b3a8352167d7bac5b2b5 (patch)
tree37e53f88a0d3aa0621e021f307bfcfe4b0c8e29b /dhall/src/semantics/resolve
parentffb7cff2ff317c81248a680e4899fa45eed00daa (diff)
spec: Enable `with` optimizations
Diffstat (limited to 'dhall/src/semantics/resolve')
-rw-r--r--dhall/src/semantics/resolve/resolve.rs32
1 files changed, 30 insertions, 2 deletions
diff --git a/dhall/src/semantics/resolve/resolve.rs b/dhall/src/semantics/resolve/resolve.rs
index 114bd9b..036e9a0 100644
--- a/dhall/src/semantics/resolve/resolve.rs
+++ b/dhall/src/semantics/resolve/resolve.rs
@@ -2,6 +2,7 @@ use itertools::Itertools;
use std::borrow::Cow;
use std::collections::BTreeMap;
use std::env;
+use std::iter::once;
use std::path::PathBuf;
use url::Url;
@@ -12,8 +13,8 @@ use crate::operations::{BinOp, OpKind};
use crate::semantics::{mkerr, Cache, Hir, HirKind, ImportEnv, NameEnv, Type};
use crate::syntax;
use crate::syntax::{
- Expr, ExprKind, FilePath, FilePrefix, Hash, ImportMode, ImportTarget, Span,
- UnspannedExpr, URL,
+ Expr, ExprKind, FilePath, FilePrefix, Hash, ImportMode, ImportTarget,
+ Label, Span, UnspannedExpr, URL,
};
use crate::{Parsed, Resolved};
@@ -276,6 +277,30 @@ fn resolve_one_import(
})
}
+/// Desugar a `with` expression.
+fn desugar_with(x: Expr, path: &[Label], y: Expr, span: Span) -> Expr {
+ use crate::operations::BinOp::RightBiasedRecordMerge;
+ use ExprKind::{Op, RecordLit};
+ use OpKind::{BinOp, Field};
+ let expr = |k| Expr::new(k, span.clone());
+ match path {
+ [] => y,
+ [l, rest @ ..] => {
+ let res = desugar_with(
+ expr(Op(Field(x.clone(), l.clone()))),
+ rest,
+ y,
+ span.clone(),
+ );
+ expr(Op(BinOp(
+ RightBiasedRecordMerge,
+ x,
+ expr(RecordLit(once((l.clone(), res)).collect())),
+ )))
+ }
+ }
+}
+
/// Desugar the first level of the expression.
fn desugar(expr: &Expr) -> Cow<'_, Expr> {
match expr.kind() {
@@ -301,6 +326,9 @@ fn desugar(expr: &Expr) -> Cow<'_, Expr> {
expr.span(),
))
}
+ ExprKind::Op(OpKind::With(x, path, y)) => {
+ Cow::Owned(desugar_with(x.clone(), path, y.clone(), expr.span()))
+ }
_ => Cow::Borrowed(expr),
}
}