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Quotations - Microsoft.FSharp.Quotations.Expr._ConstExpr
f#

Hello again,

I have another question that I hope someone can help me with. I am trying to break up a quotation that contains an assignment of a function. eg
let x =
<@@
let Sqr (x:double) = x*x;
Sqr 3.
@@>

The sequence of matches I get is
Let((var,value) - var.Text = Sqr#7668.1
Lambda(var, body) - varText = x#7664.2
App(x,y) - I cannot work out which quotation pattern match should match.

The type of both x and y are
{Microsoft.FSharp.Quotations.Expr._ConstExpr}
[Microsoft.FSharp.Quotations.Expr._ConstExpr]: {Microsoft.FSharp.Quotations.Expr._ConstExpr}

I'm at a loss as to which pattern should match or how to go about processing it. I have tried all that I though that might. My traversing function matches/processes 1*2 fine.

Many Thanks
Bart

.

The following program, an extention of Tomas program, seems to match the whole of your quotation.

#light
open Microsoft.FSharp.Quotations.Raw

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let x = 
    <@@
    let Sqr (x:double) = x*x;
    Sqr 3.
    @@>
 
let rec print expr = 
  match expr with
  | Let((var,value), body) -> 
      // Represents: let <var> = <value> in <body>
      printfn "let %s = " var.Text 
      print value
      printfn "\n"
      print body
  | Int32(n) ->
      // Represents a number
      printf "%d" n
  | GenericTopDefnApp <@@ (+) @@> (ty, a::b) ->
      // Represents: <a> + <b>
      print a
      printfn " + "
      print a
  | GenericTopDefnApp <@@ ( * ) @@> (ty, a::b) ->
      // Represents: <a> * <b>
      print a
      printfn " * "
      print a
  | Var(v) ->
      // Represents variable reference
      printf "Var: %s" v.Text
  | Seq(a,b) -> 
      // Represents: <a>; <b> (sequence expression)
      print a
      printfn ";\n"
      print b
  | Lambda(var, body) -> 
      printf "%A" var
      printf " -> "
      print body
  | App(x,y) -> 
      printfn "App"
      print x
      print y
  | Double x -> printfn "Double: %f" x
  | AnyTopDefnUse(def, types) ->
        let _,name = def.Path
        printfn "AnyTopDefnUse: %s" name
  | x -> 
      let t = Reflection.GetTypeInfoOfValue x
      printfn "Unknown value: %A Type: %A" x t 
      
print x
read_line()

One of

By on 8/31/2007 12:53 AM ()

Many thanks Robert,

Got me out of the woods. Looks like I was on the right track but did not think that the order of the patterns would make a difference. Stepping though your working code really helped. Your code produces output ... (which I was roughly expecting)

let Sqr#7683.1 =
x#7679.2 -> Var: x#7679.2 *
Var: x#7679.2
App
Var: Sqr#7683.1Double: 3.000000

My code was producing something roughly along the lines of .... (which kind of confused me)

let Sqr#7683.1 =
x#7679.2 -> App
App
AnyTopDefnUse: op_Multiply
Var: x#7679.2Var: x#7679.2

App
Var: Sqr#7683.1Double: 3.000000

Thanks again

Bart

By on 8/31/2007 10:33 AM ()

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