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Path Syntax

Paths reference data in the contract state:

/directory/subdirectory/file.type

Path Types​

ExtensionTypeExample
.ided25519 public key/parties/alice.id
.numNumeric value/terms/price.num
.textText string/metadata/description.text
.boolBoolean/flags/approved.bool
.datetimeISO 8601 timestamp/deadlines/expiry.datetime
.dateDate (YYYY-MM-DD)/terms/start.date
.hashSHA256 hash/commitments/secret.hash
.jsonJSON data/config/settings.json
.wasmWASM module/predicates/custom.wasm
.modalityModel/rule file/model/default.modality

Examples​

// Reference a party's identity
+signed_by(/parties/alice.id)

// Compare numeric values
+num_gte(/deposit/amount.num, /terms/price.num)

// Check a timestamp
+after(/deadlines/expiry.datetime)

// Verify a hash commitment
+hash_matches(/commitments/secret.hash, /revealed/value.text)

Variables​

A path segment $k is a variable, and $k.id is that variable followed by an extension. A variable stands for one segment with no dot: alice, not alice.id.

  • In a rule, a variable means every name. always([+modifies(/claimants/$k) -signed_by(/claimants/$k.id)] false) says that for every k, no later commit writes under /claimants/k unless the key at /claimants/k.id signed it.
  • On a model edge, a variable means one name the commit picks. A commit takes +signed_by(/claimants/$k.id) when some claimant's accepted key signed it. Every $k on one edge is the same name.

A segment !$k is a hole: every segment outside $k's slot. Holes go on model edges only. -modifies(/claimants/!$k) forbids a write under /claimants/bob, /claimants/bob.id, or /claimants/bob.bool for every name bob other than k. !$k.id is the .id of every other name.

// Some claimant signs, and the commit writes in her slot only
+signed_by(/claimants/$k.id) -modifies(/claimants/!$k)

// No other claimant signs
-signed_by(/claimants/!$k.id)

Limits:

  • Variables go only in the path arguments of standard predicates that read paths: signed_by, any_signed, all_signed, threshold, modifies, post_to_path, state_exists, bool_true, bool_false, text_eq, text_contains, text_starts_with, text_ends_with, num_eq, num_gt, num_gte, num_lt, num_lte, amount_in_range, sets (also spelled post_to), sent_eq, sent_lte, sent_to, and posts_own_key.
  • A hole with no extension (!$k) goes only in modifies, post_to_path, state_exists, any_signed, all_signed, and threshold. Elsewhere, write the extension: -bool_true(/claimants/!$k.bool).
  • A rule takes no holes. Its variables already range over every name.
  • Labels read accepted state. +signed_by(/claimants/$k.id) needs the key at /claimants/k.id before the commit. The commit that registers a key cannot also count as signed by it. To require that the registered key signed its own registration, use +posts_own_key(/claimants/$k.id), which reads the pending commit.

Directory Structure​

A typical contract has this structure:

my-contract/
├── .contract/           # Internal storage
├── state/               # Data files
│   ├── parties/
│   │   ├── alice.id
│   │   └── bob.id
│   ├── terms/
│   │   └── price.num
│   └── deadlines/
│       └── expiry.datetime
├── model/
│   └── default.modality
├── rules/
│   └── protection.modality
├── alice.passfile
└── bob.passfile