Soft casting with if/is

crates/aiken-lang/src/ast.rs

@@ -1679,13 +1679,15 @@ pub type TypedAssignmentKind = AssignmentKind<()>;
 
 #[derive(Debug, Clone, PartialEq, Eq, Copy, serde::Serialize, serde::Deserialize)]
 pub enum AssignmentKind<T> {
+ Is,
  Let { backpassing: T },
  Expect { backpassing: T },
 }
 
 impl From<UntypedAssignmentKind> for TypedAssignmentKind {
  fn from(kind: UntypedAssignmentKind) -> TypedAssignmentKind {
  match kind {
+ AssignmentKind::Is => AssignmentKind::Is,
  AssignmentKind::Let { .. } => AssignmentKind::Let { backpassing: () },
  AssignmentKind::Expect { .. } => AssignmentKind::Expect { backpassing: () },
  }
@@ -1701,8 +1703,13 @@ impl<T> AssignmentKind<T> {
  matches!(self, AssignmentKind::Expect { .. })
  }
 
+ pub fn if_is(&self) -> bool {
+ matches!(self, AssignmentKind::Is)
+ }
+
  pub fn location_offset(&self) -> usize {
  match self {
+ AssignmentKind::Is => 2,
  AssignmentKind::Let { .. } => 3,
  AssignmentKind::Expect { .. } => 6,
  }
@@ -1712,6 +1719,7 @@ impl<T> AssignmentKind<T> {
 impl AssignmentKind<bool> {
  pub fn is_backpassing(&self) -> bool {
  match self {
+ Self::Is => unreachable!(),
  Self::Let { backpassing } | Self::Expect { backpassing } => *backpassing,
  }
  }
@@ -1724,6 +1732,10 @@ impl<T: Default> AssignmentKind<T> {
  }
  }
 
+ pub fn is() -> Self {
+ AssignmentKind::Is
+ }
+
  pub fn expect() -> Self {
  AssignmentKind::Expect {
  backpassing: Default::default(),
@@ -1885,13 +1897,14 @@ impl TypedClauseGuard {
  }
 }
 
-pub type TypedIfBranch = IfBranch<TypedExpr>;
-pub type UntypedIfBranch = IfBranch<UntypedExpr>;
+pub type TypedIfBranch = IfBranch<TypedExpr, TypedPattern>;
+pub type UntypedIfBranch = IfBranch<UntypedExpr, AssignmentPattern>;
 
 #[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
-pub struct IfBranch<Expr> {
+pub struct IfBranch<Expr, Is> {
  pub condition: Expr,
  pub body: Expr,
+ pub is: Option<Is>,
  pub location: Span,
 }
 

crates/aiken-lang/src/expr.rs

@@ -2,10 +2,10 @@ use crate::{
  ast::{
  self, Annotation, ArgBy, ArgName, AssignmentPattern, BinOp, Bls12_381Point,
  ByteArrayFormatPreference, CallArg, Curve, DataType, DataTypeKey, DefinitionLocation,
- IfBranch, Located, LogicalOpChainKind, ParsedCallArg, Pattern, RecordConstructorArg,
+ Located, LogicalOpChainKind, ParsedCallArg, Pattern, RecordConstructorArg,
  RecordUpdateSpread, Span, TraceKind, TypedArg, TypedAssignmentKind, TypedClause,
- TypedDataType, TypedRecordUpdateArg, UnOp, UntypedArg, UntypedAssignmentKind,
- UntypedClause, UntypedRecordUpdateArg,
+ TypedDataType, TypedIfBranch, TypedRecordUpdateArg, UnOp, UntypedArg,
+ UntypedAssignmentKind, UntypedClause, UntypedIfBranch, UntypedRecordUpdateArg,
  },
  builtins::void,
  parser::token::Base,
@@ -127,7 +127,7 @@ pub enum TypedExpr {
  If {
  location: Span,
  #[serde(with = "Vec1Ref")]
- branches: Vec1<IfBranch<Self>>,
+ branches: Vec1<TypedIfBranch>,
  final_else: Box<Self>,
  tipo: Rc<Type>,
  },
@@ -564,7 +564,7 @@ pub enum UntypedExpr {
 
  If {
  location: Span,
- branches: Vec1<IfBranch<Self>>,
+ branches: Vec1<UntypedIfBranch>,
  final_else: Box<Self>,
  },
 

crates/aiken-lang/src/format.rs

@@ -2,10 +2,10 @@ use crate::{
  ast::{
  Annotation, ArgBy, ArgName, ArgVia, AssignmentKind, AssignmentPattern, BinOp,
  ByteArrayFormatPreference, CallArg, ClauseGuard, Constant, CurveType, DataType, Definition,
- Function, IfBranch, LogicalOpChainKind, ModuleConstant, OnTestFailure, Pattern,
- RecordConstructor, RecordConstructorArg, RecordUpdateSpread, Span, TraceKind, TypeAlias,
- TypedArg, UnOp, UnqualifiedImport, UntypedArg, UntypedArgVia, UntypedAssignmentKind,
- UntypedClause, UntypedClauseGuard, UntypedDefinition, UntypedFunction, UntypedModule,
+ Function, LogicalOpChainKind, ModuleConstant, OnTestFailure, Pattern, RecordConstructor,
+ RecordConstructorArg, RecordUpdateSpread, Span, TraceKind, TypeAlias, TypedArg, UnOp,
+ UnqualifiedImport, UntypedArg, UntypedArgVia, UntypedAssignmentKind, UntypedClause,
+ UntypedClauseGuard, UntypedDefinition, UntypedFunction, UntypedIfBranch, UntypedModule,
  UntypedPattern, UntypedRecordUpdateArg, Use, Validator, CAPTURE_VARIABLE,
  },
  docvec,
@@ -703,6 +703,7 @@ impl<'comments> Formatter<'comments> {
  kind: UntypedAssignmentKind,
  ) -> Document<'a> {
  let keyword = match kind {
+ AssignmentKind::Is => unreachable!(),
  AssignmentKind::Let { .. } => "let",
  AssignmentKind::Expect { .. } => "expect",
  };
@@ -1195,7 +1196,7 @@ impl<'comments> Formatter<'comments> {
 
  pub fn if_expr<'a>(
  &mut self,
- branches: &'a Vec1<IfBranch<UntypedExpr>>,
+ branches: &'a Vec1<UntypedIfBranch>,
  final_else: &'a UntypedExpr,
  ) -> Document<'a> {
  let if_branches = self
@@ -1223,10 +1224,44 @@ impl<'comments> Formatter<'comments> {
  pub fn if_branch<'a>(
  &mut self,
  if_keyword: Document<'a>,
- branch: &'a IfBranch<UntypedExpr>,
+ branch: &'a UntypedIfBranch,
  ) -> Document<'a> {
  let if_begin = if_keyword
  .append(self.wrap_expr(&branch.condition))
+ .append(match &branch.is {
+ Some(AssignmentPattern {
+ pattern,
+ annotation,
+ ..
+ }) => {
+ let is_sugar = matches!(
+ (&pattern, &branch.condition),
+ (
+ Pattern::Var { name, .. },
+ UntypedExpr::Var { name: var_name, .. }
+ ) if name == var_name
+ );
+
+ let Some(annotation) = &annotation else {
+ unreachable!()
+ };
+
+ let is = if is_sugar {
+ self.annotation(annotation)
+ } else {
+ self.pattern(pattern)
+ .append(": ")
+ .append(self.annotation(annotation))
+ .group()
+ };
+
+ break_("", " ")
+ .append("is")
+ .append(break_("", " "))
+ .append(is)
+ }
+ None => nil(),
+ })
  .append(break_("{", " {"))
  .group();