Map.find<'Key,'T> Function (F#)
Looks up an element in the map. If no binding exists in the map, raises KeyNotFoundException.
Namespace/Module Path: Microsoft.FSharp.Collections.Map
Assembly: FSharp.Core (in FSharp.Core.dll)
// Signature:
Map.find : 'Key -> Map<'Key,'T> -> 'T (requires comparison)
// Usage:
Map.find key table
key
Type: 'KeyThe input key.
table
Type: Map<'Key,'T>The input map.
Exception |
Condition |
---|---|
Thrown when the key does not exist in the map. |
The value mapped to the given key.
This function is named Find in compiled assemblies. If you are accessing the function from a language other than F#, or through reflection, use this name.
The following examples shows how to use Map.filter.
let findAndPrint key map =
printfn "With key %d, found value %A." key (Map.find key map)
let map1 = Map.ofList [ (1, "one"); (2, "two"); (3, "three") ]
let map2 = Map.ofList [ for i in 1 .. 10 -> (i, i*i) ]
try
findAndPrint 1 map1
findAndPrint 2 map1
findAndPrint 3 map2
findAndPrint 5 map2
// The key is not in the map, so this throws an exception.
findAndPrint 0 map2
with
:? System.Collections.Generic.KeyNotFoundException as e -> printfn "%s" e.Message
Output
With key 1, found value "one". With key 2, found value "two". With key 3, found value 9. With key 5, found value 25. The given key was not present in the dictionary.
Windows 8, Windows 7, Windows Server 2012, Windows Server 2008 R2
F# Core Library Versions
Supported in: 2.0, 4.0, Portable