var query = EF.CompileQuery((SomeDbContext context, string foo)
    => context.Set<Order>().Where(c => c.Foo == foo).Count());

var query = EF.CompileQuery((SomeDbContext context, string foo)
    => context.Set<Order>().Where(c => c.Foo == foo).Count() == 1);

Unhandled exception. System.InvalidCastException: Unable to cast object of type 'System.Linq.Expressions.LogicalBinaryExpression' to type 'System.Linq.Expressions.MethodCallExpression'.
   at MongoDB.Driver.Linq.Linq3Implementation.Translators.ExpressionToExecutableQueryTranslators.ExpressionToExecutableQueryTranslator.TranslateScalar[TDocument,TResult](MongoQueryProvider`1 provider, Expression expression, ExpressionTranslationOptions translationOptions)
   at MongoDB.Driver.Linq.Linq3Implementation.MongoQueryProvider`1.Execute[TResult](Expression expression)
   at MongoDB.EntityFrameworkCore.Storage.MongoClientWrapper.ExecuteScalar[T](MongoExecutableQuery executableQuery)
   at MongoDB.EntityFrameworkCore.Storage.MongoClientWrapper.Execute[T](MongoExecutableQuery executableQuery, Action& log)
   at MongoDB.EntityFrameworkCore.Query.QueryingEnumerable`2.Enumerator.MoveNextHelper()
   at MongoDB.EntityFrameworkCore.Query.QueryingEnumerable`2.Enumerator.MoveNext()
   at System.Linq.Enumerable.TryGetSingle[TSource](IEnumerable`1 source, Boolean& found)
   at lambda_method26(Closure, QueryContext)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryBase`2.ExecuteCore(TContext context, CancellationToken cancellationToken, Object[] parameters)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryBase`2.ExecuteCore(TContext context, Object[] parameters)
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQuery`2.Execute[TParam1](TContext context, TParam1 param1)
   at Program.<Main>$(String[] args) in /Users/arthur.vickers/code/OnYourOwnNow/OnYourOwnNow/Program.cs:line 14