Package

std/core/checks

std/checks — runtime assertions / preconditions / postconditions.

Each helper throws on violation rather than aborting, so user
code can catch and recover when appropriate. The caller's
message is forwarded into the exception, so e.message reads
it back in the catch handler.

Naming follows Objects.requireNonNull /
assert / Preconditions.checkArgument conventions:

• require* = precondition (throws IllegalArgumentException)
• check* = state invariant (throws IllegalStateException)
• ensure* = postcondition (throws IllegalStateException)

Free functions

Type	Method and description
`void`	requireTrue(condition : bool, message : string) : void Require `condition` to hold; throw `IllegalArgumentException(message)` otherwise.
`void`	requireFalse(condition : bool, message : string) : void Require `condition` to be false; throw `IllegalArgumentException(message)` otherwise.
`void`	requirePositive(value : i64, message : string) : void Require `value > 0`; throw `IllegalArgumentException(message)` otherwise. Zero is rejected (use `requireNonNegative` to allow it).
`void`	requireNonNegative(value : i64, message : string) : void Require `value >= 0`; throw `IllegalArgumentException(message)` otherwise.
`void`	requireInRange( value : i64, min : i64, max : i64, message : string ) : void Require `min <= value <= max` (both bounds inclusive); throw `IllegalArgumentException(message)` otherwise.
`void`	checkState(condition : bool, message : string) : void State invariants (different exception type so catch handlers can distinguish a bad input from a bad object state).
`void`	fail(message : string) : void Hard fail — never returns. Useful for "unreachable" branches the type checker can't prove dead.
`void`	requireNonEmpty(s : string, message : string) : void Require `s` to be non-empty; throw `IllegalArgumentException` (prefixed with the check name) otherwise.

Method detail

#requireTrue

requireTrue(condition : bool, message : string) : void ! IllegalArgumentException

Require condition to hold; throw IllegalArgumentException(message)
otherwise.

Parameters

condition precondition that must be true to pass

message text forwarded into the exception when it fails

#requireFalse

requireFalse(condition : bool, message : string) : void ! IllegalArgumentException

Require condition to be false; throw IllegalArgumentException(message)
otherwise.

Parameters

condition precondition that must be false to pass

message text forwarded into the exception when it fails

#requirePositive

requirePositive(value : i64, message : string) : void ! IllegalArgumentException

Require value > 0; throw IllegalArgumentException(message) otherwise.
Zero is rejected (use requireNonNegative to allow it).

Parameters

value number that must be strictly greater than 0

message text forwarded into the exception when it fails

#requireNonNegative

requireNonNegative(value : i64, message : string) : void ! IllegalArgumentException

Require value >= 0; throw IllegalArgumentException(message) otherwise.

Parameters

value number that must be zero or greater

message text forwarded into the exception when it fails

#requireInRange

requireInRange( value : i64, min : i64, max : i64, message : string ) : void ! IllegalArgumentException

Require min <= value <= max (both bounds inclusive); throw
IllegalArgumentException(message) otherwise.

Parameters

value number checked against the inclusive bounds

min inclusive lower bound

max inclusive upper bound

message text forwarded into the exception when it fails

#checkState

checkState(condition : bool, message : string) : void ! IllegalStateException

State invariants (different exception type so catch handlers can
distinguish a bad input from a bad object state).

Parameters

condition state invariant that must be true to pass

message text forwarded into the IllegalStateException

#fail

fail(message : string) : void ! IllegalStateException

Hard fail — never returns. Useful for "unreachable" branches the
type checker can't prove dead.

Parameters

message text forwarded into the thrown IllegalStateException

#requireNonEmpty

requireNonEmpty(s : string, message : string) : void ! IllegalArgumentException

Require s to be non-empty; throw IllegalArgumentException
(prefixed with the check name) otherwise.

Parameters

s string that must have a non-zero byte length

message detail appended after the "requireNonEmpty: " prefix