nickel/examples

Examples

This directory contain an evolving selection of examples of Nickel programs.

Execution

Please follow the main repository's README instructions to have a working nickel executable. You can then either use one-liner commands or launch an interactive session:

From the command line

• Base values: some examples just return numbers, strings or booleans. You can run them directly:

  $ nickel -f fibonacci.ncl
  Done: Num(55.0)
  

• Configurations: some return records representing configuration. Because of laziness, Nickel won't currently print any readable result as is. Please use the export subcommand to see the result serialized as JSON:

  $ nickel -f merge-main.ncl export
  {
    "firewall": {
    ...
  }
  

  Alternatively, you can query a configuration or a sub-element to get list of attributes or the documentation:

  $ nickel -f record-contract.ncl query kind
    • contract: <ReplicationController, ReplicaSet, Pod>
    • value: `ReplicationController
    • documentation: The kind of the element being configured.
  

From the REPL

First start the REPL:

$ nickel repl
nickel>

• Just import a file directly to evaluate it:

  nickel> import "fibonacci.ncl"
  55
  
  nickel>
  

• Use builtins.serialize to have the same behavior as the export subcommand and print the result as JSON:

  nickel> builtins.serialize `Json (import "merge-main.ncl")
  "{
      \"firewall\": {
      ...
  }"
  
  nickel>
  

• Use :query to retrieve information and documentation about a field:

  nickel>let config = import "record-contract.ncl"
  nickel>:query config.kind
  • contract: <ReplicationController, ReplicaSet, Pod>
  • value: `ReplicationController
  • documentation: The kind of the element being configured.
  
  nickel>