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std.logic

Prolog/miniKanren-style goal combinators built over the unification primitives.

(import std.logic)

Unification

Symbol	Description
`(== a b)`	Unification goal: succeed when `a` and `b` unify.
`(==o a b)`	Goal-form alias of `==`.
`(copy-term* t)`	Copy a term, replacing logic variables with fresh ones.

Symbol	Description
`(succeedo)`	Goal that always succeeds.
`(failo)`	Goal that always fails.
`(disj g1 g2 ...)`	Logical disjunction.
`(conj g1 g2 ...)`	Logical conjunction.
`(fresh (vars ...) body ...)`	Introduce fresh logic variables.
`(fresh-vars n)`	Build a list of `n` fresh variables.
`(conde clause ...)`	Disjunction of conjunction clauses.
`(conda clause ...)`	Soft-cut conjunction.
`(condu clause ...)`	Committed-choice conjunction.
`(onceo g)`	Restrict `g` to its first solution.
`(naf g)`	Negation as failure.
`(goal thunk)`	Wrap a thunk into a goal.

Symbol	Description
`(membero x xs)`	Goal: `x` is a member of list `xs`.

Symbol	Description
`(succeeds? g)`	True when goal `g` has at least one solution.
`(findall var g)`	List of all solutions of `var` under `g`.
`(run1 vars g)`	First solution.
`(run* vars g)`	All solutions.
`(run-n n vars g)`	First `n` solutions.

Symbol	Description
`(logic-throw tag value)`	Raise a logic-tagged condition.
`(logic-catch tag thunk handler)`	Catch a logic-tagged condition.

Source: stdlib/std/logic.eta