I can convert a quotation of type Expr<'a -> 'b>
to a Linq expression via the following snippet:
/// Converts a F# Expression to a LINQ Lambda
let toLambda (exp:Expr) =
let linq = exp.ToLinqExpression() :?> MethodCallExpression
linq.Arguments.[0] :?> LambdaExpression
/// Converts a Lambda quotation into a Linq Lamba Expression with 1 parameter
let ToLinq (exp : Expr<'a -> 'b>) =
let lambda = toLambda exp
Expression.Lambda<Func<'a, 'b>>(lambda.Body, lambda.Parameters)
Now I want to convert a quotation of type Expr<'a * 'b -> 'c>
or maybe even Expr<'a -> 'b -> 'c>
to a Linq Lambda Expression of type Expression<Func<'a,'b'c>>
.
How can I do this?
Regards, forki
I'm not sure if this is directly supported by the LINQ modules available in the F# PowerPack. However, you can implement your own post-processing of the LINQ expression produced by F# libraries to turn it into a C# lambda function of the usual form:
The following function takes a LINQ expression which is constructed as multiple nested LambdaExpression
expressions of a single parameter (that is, the structure produced by F# translator) and returns a list of parameters and body of the inner-most expression:
let rec translateExpr (linq:Expression) =
match linq with
| :? MethodCallExpression as mc ->
let le = mc.Arguments.[0] :?> LambdaExpression
let args, body = translateExpr le.Body
le.Parameters.[0] :: args, body
| _ -> [], linq
Now you can use it to get an ordinary Func
delegate out of type such as int -> int -> int -> int
like this:
let linq = (<@@ fun a b c -> (a + b) * c @@>).ToLinqExpression()
let args, body = translateExpr liq
let f = Expression.Lambda<Func<int, int, int, int>>
(body, args |> Array.ofSeq)
f.Compile().Invoke(10, 11, 2)
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With