Formulaic language is important to language acquisition; however, English language learners are often reported to have problems with formulaic expressions. Several lists of formulaic sequences have been proposed, mainly for developing teaching and testing materials. However, their limited numbers and insufficient usage information seem unable to benefit formulaic language use. To address these issues we have developed GRASP, a reference aid for formulaic expressions, to promote learners' productive competence. Users are allowed multi-word inputs to target their desired phrases or collocations. Utilizing natural language processing techniques, our system categorizes and displays the structures and sequences in a hierarchical way. The corresponding example sentences are also provided. The formulaic structures serve as a quick access index. The formulaic sequences and corpus examples illustrate the real world language use. Importantly, automatic summarization from language data lends support to the idea of data-driven learning. A single-group pre-posttest design was adopted to assess the effectiveness of GRASP on 150 Chinese-speaking college freshmen. The results indicated that our reference aid made a substantial contribution to students' performance on formulaic expression use in a sentence completion task, compared with the existing tools. Notably, the less proficient students showed marked improvement.