Function FreshVariable

ast/ast.go:1338–1350

FreshVariable returns a variable different from the ones in used.

(used map[Variable]bool)

// FreshVariable returns a variable different from the ones in used.
func FreshVariable(used map[Variable]bool) Variable {
	makeFresh := func(n int) Variable { return Variable{fmt.Sprintf("X%d", n)} }
	i := 0
	for {
		v := makeFresh(i)
		if used[v] {
			i++
			continue
		}
		used[v] = true
		return v
	}
}

// ReplaceWildcards returns a new term where each wildcard is replaced
// with a fresh variables. The used-variables map is modified to keep track