F# instead of multiple lets , can I pipe the intermediate results

Question

Given:

let json = """
{
    "KeyValuePairs": "[{\"Key\" : \"one\", \"Value\" : \"1\"},{\"Key\" : \"two\", \"Value\" : \"2\"}]"
}
"""
let dict = JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
let kvpairs = dict.["KeyValuePairs"]
let kvlist = JsonConvert.DeserializeObject<KeyValuePair<System.String, System.String> List>(kvpairs)
let kvmap = [for kv  in kvlist -> (kv.Key, kv.Value)] |> Map.ofList

Can I use one expression with pipes instead of intermediate variables? If so, what would that look like?

FWIW I tried:

let kvpairs = JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
    |> (fun d -> d.["KeyValuePairs"])

but that gave me the error:

 error FS0010: Unexpected infix operator in binding. Expected incomplete structured construct at or before this point or other 

token.

Update: What about the other way around: piping into JsonConvert?

let kvpairs = 
    json
    |> JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>
    |> (fun d -> d.["KeyValuePairs"])

This gives me:

error FS0717: Unexpected type arguments

Answer 1

In your code

let kvpairs = JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
    |> (fun d -> d.["KeyValuePairs"])

The pipe is not indented far enough.

let kvpairs = JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
              |> (fun d -> d.["KeyValuePairs"])

or

let kvpairs = JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
           |> (fun d -> d.["KeyValuePairs"])

or

let kvpairs = 
    JsonConvert.DeserializeObject<Dictionary<System.String, System.String>>(json) 
    |> (fun d -> d.["KeyValuePairs"])

will work.