Harshad numbers / Niven numbers

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open System

let isHarshad x =
    (decimal x) / (x.ToString() 
    |> Seq.map(string >> Decimal.Parse) |> Seq.sum) % 1m = 0m

// [ 1 .. 100 ] |> List.filter isHarshad

namespace System

val isHarshad : x:int -> bool

Full name: Script.isHarshad

val x : int

Multiple items
val decimal : value:'T -> decimal (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.decimal

--------------------
type decimal = Decimal

Full name: Microsoft.FSharp.Core.decimal

--------------------
type decimal<'Measure> = decimal

Full name: Microsoft.FSharp.Core.decimal<_>

Int32.ToString() : string
Int32.ToString(provider: IFormatProvider) : string
Int32.ToString(format: string) : string
Int32.ToString(format: string, provider: IFormatProvider) : string

module Seq

from Microsoft.FSharp.Collections

val map : mapping:('T -> 'U) -> source:seq<'T> -> seq<'U>

Full name: Microsoft.FSharp.Collections.Seq.map

Multiple items
val string : value:'T -> string

Full name: Microsoft.FSharp.Core.Operators.string

--------------------
type string = String

Full name: Microsoft.FSharp.Core.string

Multiple items
type Decimal =
  struct
    new : value:int -> decimal + 7 overloads
    member CompareTo : value:obj -> int + 1 overload
    member Equals : value:obj -> bool + 1 overload
    member GetHashCode : unit -> int
    member GetTypeCode : unit -> TypeCode
    member ToString : unit -> string + 3 overloads
    static val Zero : decimal
    static val One : decimal
    static val MinusOne : decimal
    static val MaxValue : decimal
    ...
  end

Full name: System.Decimal

--------------------
Decimal()
Decimal(value: int) : unit
Decimal(value: uint32) : unit
Decimal(value: int64) : unit
Decimal(value: uint64) : unit
Decimal(value: float32) : unit
Decimal(value: float) : unit
Decimal(bits: int []) : unit
Decimal(lo: int, mid: int, hi: int, isNegative: bool, scale: byte) : unit

Decimal.Parse(s: string) : decimal
Decimal.Parse(s: string, provider: IFormatProvider) : decimal
Decimal.Parse(s: string, style: Globalization.NumberStyles) : decimal
Decimal.Parse(s: string, style: Globalization.NumberStyles, provider: IFormatProvider) : decimal

val sum : source:seq<'T> -> 'T (requires member ( + ) and member get_Zero)

Full name: Microsoft.FSharp.Collections.Seq.sum