§

MUST

Creates an obligation for a party to perform an action. The party is required to do something.

Syntax

PARTY partyName MUST DO action
PARTY partyName MUST DO action WITHIN deadline
PARTY partyName MUST NOT DO action

Purpose

MUST expresses a legal obligation - something that a party is required to do. If not fulfilled within the deadline, consequences (LEST) may apply.

Examples

Example file:

-- MUST Keyword Examples - Legal Obligations

-- Type Declarations

DECLARE `Contract Party` IS ONE OF
  `The Borrower`
  `The Lender`
  `The Buyer`
  `The Seller`
  `The Contractor`
  `The Client`
  `The Tenant`
  `The Landlord`

DECLARE `Contract Action` IS ONE OF
  `make payment` HAS `payment amount` IS A NUMBER
  `deliver goods` HAS `goods description` IS A STRING
  `provide services` HAS `service description` IS A STRING
  `sign contract`
  `provide notice` HAS `notice content` IS A STRING
  `complete repairs` HAS `repair description` IS A STRING
  `pay penalty` HAS `penalty amount` IS A NUMBER
  `return security deposit` HAS `deposit amount` IS A NUMBER

-- Basic Payment Obligation

-- Simple payment obligation with a deadline
-- The Borrower must make a payment of $10,000 within 30 days
`monthly loan payment` MEANS
  PARTY `The Borrower`
  MUST `make payment` 10000
  WITHIN 30

-- With HENCE (Consequence on Fulfillment)

-- Purchase contract: If The Buyer pays, then The Seller must deliver
-- This creates a conditional chain of obligations
`purchase and delivery agreement` MEANS
  PARTY `The Buyer`
  MUST `make payment` 25000
  WITHIN 7
  HENCE
    PARTY `The Seller`
    MUST `deliver goods` "industrial machinery"
    WITHIN 14

-- Service contract: After payment, contractor provides services,
-- then client pays the remaining balance
`staged service contract` MEANS
  PARTY `The Client`
  MUST `make payment` 5000  -- Initial deposit
  WITHIN 3
  HENCE
    PARTY `The Contractor`
    MUST `provide services` "website development"
    WITHIN 30
    HENCE
      PARTY `The Client`
      MUST `make payment` 15000  -- Final payment
      WITHIN 7

-- With LEST (Consequence on Breach)

-- Simple breach: If The Borrower doesn't pay, the contract is breached
`payment or breach` MEANS
  PARTY `The Borrower`
  MUST `make payment` 5000
  WITHIN 30
  LEST BREACH

-- Penalty clause: If payment not made on time, a late fee applies
-- with a grace period before final breach
`payment with late fee` MEANS
  PARTY `The Borrower`
  MUST `make payment` 10000
  WITHIN 30
  LEST
    PARTY `The Borrower`
    MUST `make payment` 12000  -- Original amount plus 20% late fee
    WITHIN 45  -- 15-day grace period
    LEST BREACH

-- Landlord repair obligation: Must repair within deadline,
-- or tenant can deduct repair costs from rent
`landlord repair obligation` MEANS
  PARTY `The Landlord`
  MUST `complete repairs` "fix leaking roof"
  WITHIN 14
  LEST
    PARTY `The Tenant`
    MUST `provide notice` "tenant will arrange repairs and deduct cost"
    WITHIN 3

-- MUST NOT (Prohibition)

-- MUST NOT is equivalent to SHANT - expresses a prohibition
-- The Contractor must not disclose confidential information
-- for 2 years (730 days)
`confidentiality obligation` MEANS
  PARTY `The Contractor`
  MUST NOT `provide notice` "confidential information disclosure"
  WITHIN 730

-- Chained Obligations

-- Complex contract with multiple sequential obligations
-- Demonstrates a complete contract lifecycle
`construction contract workflow` MEANS
  PARTY `The Contractor`
  MUST `sign contract`
  WITHIN 7
  HENCE
    PARTY `The Client`
    MUST `make payment` 50000  -- Down payment
    WITHIN 14
    HENCE
      PARTY `The Contractor`
      MUST `provide services` "foundation work"
      WITHIN 30
      HENCE
        PARTY `The Client`
        MUST `make payment` 150000  -- Final payment
        WITHIN 7

-- Lease agreement with security deposit return
`lease termination and deposit return` MEANS
  PARTY `The Tenant`
  MUST `provide notice` "60-day notice of non-renewal"
  WITHIN 60
  HENCE
    PARTY `The Tenant`
    MUST `complete repairs` "restore premises to original condition"
    WITHIN 30
    HENCE
      PARTY `The Landlord`
      MUST `return security deposit` 3000
      WITHIN 14
      LEST
        PARTY `The Landlord`
        MUST `return security deposit` 3090  -- With 3% interest penalty
        WITHIN 30
        LEST BREACH

-- Testing Obligations

-- Test 1: Basic obligation fulfilled on time
#TRACE `monthly loan payment` AT 0 WITH
  PARTY `The Borrower` DOES `make payment` 10000 AT 20

-- Test 2: Basic obligation breached (no payment made)
#TRACE `monthly loan payment` AT 0 WITH

-- Test 3: Conditional obligation - full chain executed
#TRACE `purchase and delivery agreement` AT 0 WITH
  PARTY `The Buyer` DOES `make payment` 25000 AT 5
  PARTY `The Seller` DOES `deliver goods` "industrial machinery" AT 15

-- Test 4: Payment with late fee - paid during grace period
#TRACE `payment with late fee` AT 0 WITH
  PARTY `The Borrower` DOES `make payment` 12000 AT 40

-- Test 5: Payment with late fee - breached (no payment at all)
#TRACE `payment with late fee` AT 0 WITH

-- Test 6: Staged service contract - complete workflow
#TRACE `staged service contract` AT 0 WITH
  PARTY `The Client` DOES `make payment` 5000 AT 2
  PARTY `The Contractor` DOES `provide services` "website development" AT 25
  PARTY `The Client` DOES `make payment` 15000 AT 30

-- Test 7: Construction workflow - happy path
#TRACE `construction contract workflow` AT 0 WITH
  PARTY `The Contractor` DOES `sign contract` AT 5
  PARTY `The Client` DOES `make payment` 50000 AT 15
  PARTY `The Contractor` DOES `provide services` "foundation work" AT 40
  PARTY `The Client` DOES `make payment` 150000 AT 45

-- Test 8: Lease termination with deposit return
#TRACE `lease termination and deposit return` AT 0 WITH
  PARTY `The Tenant` DOES `provide notice` "60-day notice of non-renewal" AT 30
  PARTY `The Tenant` DOES `complete repairs` "restore premises to original condition" AT 55
  PARTY `The Landlord` DOES `return security deposit` 3000 AT 65

-- Test 9: Landlord repair obligation - landlord complies
#TRACE `landlord repair obligation` AT 0 WITH
  PARTY `The Landlord` DOES `complete repairs` "fix leaking roof" AT 10

-- Test 10: Landlord repair obligation - tenant must notify
#TRACE `landlord repair obligation` AT 0 WITH

Obligation Fulfillment

  • Obligation is fulfilled when the party performs the action before the deadline
  • Obligation is breached when the deadline passes without the action
  • Consequences in LEST clause activate on breach
  • PARTY - Identifies who has the obligation
  • MAY - Permission (optional action)
  • SHANT - Prohibition
  • REGULATIVE - Full regulative rule reference