object

validated

Types and predicates for type-checking and handling lists of validation terms. Inspired by Scala Cats and Kotlin Arrow.

Availability:

logtalk_load(validations(loader))

Author: Paulo Moura

Version: 1:0:0

Date: 2026-02-22

Compilation flags:

static, context_switching_calls

Provides:

type::type/1

type::check/2

arbitrary::arbitrary/1

arbitrary::arbitrary/2

arbitrary::shrinker/1

arbitrary::shrink/3

arbitrary::edge_case/2

Uses:

list

random

type

Remarks:

• Type-checking support: Defines a validated(ValueType, ErrorType) type for checking validation terms where the value and error terms must be of the given types.

• QuickCheck support: Defines clauses for the type::arbitrary/1-2, arbitrary::shrinker/1, arbitrary::shrink/3, and arbitrary::edge_case/2 predicates to allow generating random values for the validated(ValueType, ErrorType) type.

Inherited public predicates:

(none)

Public predicates

valids/2

Returns the values stored in validation terms that hold valid values.

Compilation flags:

static

Template:

valids(Validations,Values)

Mode and number of proofs:

valids(+list(validation),-list) - one

---

invalids/2

Returns a flattened list with all errors stored in invalid validation terms.

Compilation flags:

static

Template:

invalids(Validations,Errors)

Mode and number of proofs:

invalids(+list(validation),-list) - one

---

partition/3

Retrieves and partitions valid values and flattened accumulated errors from validation terms.

Compilation flags:

static

Template:

partition(Validations,Values,Errors)

Mode and number of proofs:

partition(+list(validation),-list,-list) - one

---

map/3

Applies a closure to each list element to generate validation terms and returns a pair Values-Errors accumulating all valid values and all errors in one pass.

Compilation flags:

static

Template:

map(Closure,Terms,ValuesErrors)

Meta-predicate template:

map(2,*,*)

Mode and number of proofs:

map(+callable,+list,--compound) - one

---

map/4

Applies a closure to each list element to generate validation terms and returns valid values and accumulated errors in one pass.

Compilation flags:

static

Template:

map(Closure,Terms,Values,Errors)

Meta-predicate template:

map(2,*,*,*)

Mode and number of proofs:

map(+callable,+list,-list,-list) - one

---

sequence/2

Sequences a list of validation terms into a single validation term, accumulating all errors.

Compilation flags:

static

Template:

sequence(Validations,Validation)

Mode and number of proofs:

sequence(+list(validation),--nonvar) - one

---

traverse/3

Applies a closure to each list element to generate validation terms and then sequences them, accumulating all errors.

Compilation flags:

static

Template:

traverse(Closure,Terms,Validation)

Meta-predicate template:

traverse(2,*,*)

Mode and number of proofs:

traverse(+callable,+list,--nonvar) - one

---

Protected predicates

(no local declarations; see entity ancestors if any)

Private predicates

(no local declarations; see entity ancestors if any)

Operators

(none)

See also

validation, validation(Validation), type, arbitrary