* Add immediate/delayed notion to the manual * Split custom contracts in immediate and delayed part This commit explicitly split the custom contract representation and constructors into an immediate part, similar to a validator, and a delayed part, which is a partial identity. The stdlib and primops are adapted as well (`%contract/custom%` now takes two arguments, the two parts, and `%contract/from_xxx%` operators aren't used anymore as they are subsumed by `%contract/custom%`). * Rework prepare_contract to be more low-level and use null comparison * Make `%contract/get_xxx%` panic on a Type In the long run, we want that `%contract/get_immediate%` and `%contract/get_delayed%` works as well on types, by calling to the right function from the internals module. However, this requires deeper changes, and is left for future work. Since those primops have just been introduced, there's no reason they'd be used already in the wild, so for now, we make the implemention panic if we try to apply them to a Type. * Update stdlib doc, manual and examples Update various documentation to reflect the new custom contract constructor with an immediate and a delayed part. * Update config-gcc example with new custom contract builder * Fix tests * Implement review suggestions Co-authored-by: jneem <joeneeman@gmail.com> * Review suggestion: use concrete example for delayed checks * Review suggestion: deduplicate custom contracts in-code doc * Update Topiary input to avoid CI error (gitsavannah) --------- Co-authored-by: jneem <joeneeman@gmail.com> |
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.. | ||
arrays | ||
config-gcc | ||
fibonacci | ||
foreach-pattern | ||
imports | ||
merge | ||
merge-priorities | ||
polymorphism | ||
record-contract | ||
simple-contracts | ||
README.md |
Examples
This directory contains 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 the command line or launch an interactive session. Play with the values to see contracts failing when fed with invalid data!
From the command line
-
Base values: some examples just return numbers, strings or booleans. You can run them directly:
$ nickel eval fibonacci.ncl 55
-
Configurations: some examples return records representing configuration. You can run them directly as well, or use the
export
subcommand to see the result serialized as JSON, which might be more readable:$ nickel export merge-main.ncl { "firewall": { ... }
Alternatively, you can query individual elements of a configuration, showing documentation and other metadata:
$ nickel query --field kind record-contract.ncl • contract: [|'ReplicationController, 'ReplicaSet, 'Pod|] • 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
std.serialize
to have the same behavior as theexport
subcommand and print the result as JSON:nickel> builtin.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 |] • documentation: The kind of the element being configured. nickel>