Class AlphaRenamer

Eliminates name conflicts for variables in expression trees. Because variables get represented by ParameterExpression nodes which have referential identity, syntactic name conflicts can occur.

Inheritance

System.Object

AlphaRenamer

Namespace: System.Linq.CompilerServices

Assembly: Nuqleon.Linq.CompilerServices.dll

Syntax

public static class AlphaRenamer : Object

Examples

Consider the following definitions of the well-known K and I combinators:

K = \x.\y.x
I = \x.x

The following function is a valid representation of KI = (\x.\y.x)(\x.x) = \y.\x.x

var x1 = Expression.Parameter(typeof(int), "x");
var x2 = Expression.Parameter(typeof(int), "x");
var ki = Expression.Lambda(Expression.Lambda(x2, x2), x1); // x => x => x

The following function is a valid representation of K = \x.\y.x

var x1 = Expression.Parameter(typeof(int), "x");
var x2 = Expression.Parameter(typeof(int), "x");
var k  = Expression.Lambda(Expression.Lambda(x1, x2), x1); // x => x => x

Syntactically, both functions have an identical textual representation, requiring object identity checks to distinguish their semantic meaning.

Methods

EliminateNameConflicts(Expression)

Eliminates name conflicts for bound variables in the given expression, by substituting conflicting occurrences for fresh parameter expressions.

Declaration

public static Expression EliminateNameConflicts(Expression expression)

Parameters

Type	Name	Description
System.Linq.Expressions.Expression	expression	Expression to eliminate name conflicts in.

Returns

Type	Description
System.Linq.Expressions.Expression	Expression without name conflicts for bound variables. Global variables are not affected.