accepts

accepts

Declare the input contract for a machine. The accepts section defines what data a machine expects to receive when invoked. Each field has a name, type, and optional modifiers (required, default value, validation constraints). The runtime validates incoming data against this contract before execution begins.

Replaces the legacy provides > inputs syntax. The parser accepts both forms; run mashin fmt to auto-migrate.

When to use

Every machine that takes input should have an accepts section. Omit it only for machines that are triggered purely by events (via subscribes) or schedules with no parameters.

Syntax

accepts
  <field_name> as <type>, <modifiers>
  ...

Field declaration

Each field follows the pattern:

<name> as <type>, <modifier1>, <modifier2>, ...

Types

Type	Description	Example
text / string	Text value	name as text
number	Numeric value (integer or decimal)	count as number
integer	Integer only	age as integer
decimal	Decimal/float	score as decimal
boolean	True or false	active as boolean
list	Array of values	items as list
list of <type>	Typed list	tags as list of text
map	Key-value object	metadata as map
any	Any type (untyped)	data as any

Modifiers

Modifier	Description	Example
is required	Field must be provided	name as text, is required
default: <value>	Default value if not provided	limit as number, default: 10
description "<text>"	Human-readable description (shown in UI)	email as text, description "User email address"
label "<text>"	Display label for the visual builder	email_id as text, label "Email"

Validation constraints

Constraint	Applies to	Description	Example
min: <n>	number, integer	Minimum value	age as integer, min: 0
max: <n>	number, integer	Maximum value	age as integer, max: 150
min_length: <n>	text	Minimum string length	name as text, min_length: 2
max_length: <n>	text	Maximum string length	name as text, max_length: 100
format: "<fmt>"	text	Format validation	email as text, format: "email"
pattern: "<regex>"	text	Regex pattern match	code as text, pattern: "^[A-Z]+$"
choices: [...]	text	Allowed values (whitelist)	role as text, choices: ["admin", "user"]
exclude: [...]	text	Disallowed values (blacklist)	status as text, exclude: ["deleted"]
subset: [...]	list	List items must be from this set	teams as list, subset: ["eng", "design"]
range: [lo, hi]	number	Value must be within range	score as number, range: [0.0, 1.0]

Accessing input values

Inside steps, input fields are accessed via input.<field_name>:

compute greet
  {greeting: "Hello, " + input.name + "!"}

Examples

Simple inputs

accepts
  name as text, is required
  age as integer
  active as boolean, default: true

With validation constraints

accepts
  email as text, is required, format: "email"
  username as text, is required, min_length: 3, max_length: 20, pattern: "^[a-zA-Z0-9_]+$"
  age as integer, is required, min: 13, max: 150
  role as text, default: "member", choices: ["member", "admin", "moderator"]
  score as number, range: [0.0, 1.0]

With UI hints

accepts
  email_id as text, is required, description "Gmail message ID to process", label "Email"
  intent as text, is required, description "What the user wants to do with this email"
  max_length as integer, default: 500, description "Maximum response length in characters"

Full machine with accepts

machine email_triage
  accepts
    subject as text, is required
    body as text, is required
    sender as text
    is_vip as boolean, default: false

  responds with
    priority as text
    action as text

  implements
    ask classify, using: "anthropic:claude-haiku-4"
      with task "Triage this email. Subject: ${input.subject}\nBody: ${input.body}\nVIP: ${input.is_vip}"
      returns
        priority as text
        action as text
      assuming
        priority: "medium"
        action: "review"

Governance

Input validation happens before the governance interpreter runs. If a required field is missing or a constraint is violated, the machine rejects the input with a validation error. No steps execute, no governance decisions are made, and no behavioral ledger entries are created for the failed invocation.

This means accepts serves as the first line of defense: type-safe, schema-validated input that reaches the steps is guaranteed to match the declared contract.

Translations

Language	Keyword
English	accepts
Spanish	acepta
French	accepte
German	akzeptiert
Japanese	受け取る
Chinese	接受
Korean	받는다

See also

• responds with - Output contract declaration
• implements - Where steps use input values
• verifies - Test cases that provide sample inputs via given
• achieves - Goal examples that define input/output pairs