Janet 1.39.1-e9c6678 Documentation
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schema

Simple schema validation library. Specify structure declaratively, and get functions that will check that structure and either raise an error or return a boolean. While reasonably general, use is intended for data such as one would find in configuration files or network protocols.

Currently does not support more advanced features such as:

• Recursive schemas
• Full error reporting (only a single error is reported)
• PEG style grammars (used to enable recursion in PEGs)
• Unification (such as in the (match) macro)
• Parsing/data extraction

Syntax:

• :keyword - match any value of that type
• Tuples are used to match various combinators:
  • (any) - match any one value
  • (enum & options) - match any of the option values
  • (or & schemas) - similar to enum, but each option is considered a schema.
  • (and & schemas) - Only matches if all clauses match
  • (values schema) - Matches only if schema matches all values in a data structure.
  • (keys schema) - Matches only if schema matches all keys in a data structure.
  • (props & k v) - Takes a sequence of keys and values (alternating in order). Only matches
  the data if, for a key, the corresponding schema `v` matches.
  • (length l) - Only match if the data has a length of l. Uses of the length combinator should assert the data type before doing a length check.
  • (length min max) - Only match lengths between min and max inclusive
  • (peg pattern) - Matches only if the peg matches
  • (not pattern) - Only matches if pattern does not match
  • (pred predicate) - Use a predicate function (function of 1 argument) to check if the data is valid.
• anything else - match that value literally

Reference

schema/make-predicate schema/make-validator schema/predicate schema/validator

(make-predicate schema)

Generate a function that can be used to validate a data structure. This is the function form of `predicate`.

(make-validator schema)

Generate a function that can be used to validate a data structure. This is the function form of `validator`.

(predicate pattern)

Make a validation predicate given a certain schema.

(validator pattern)

Make a validation function of one argument. A validation function will throw an error on validation failure, otherwise, it will return the argument.