32 lines
958 B
Racket
32 lines
958 B
Racket
#lang typed/syndicate
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(require rackunit/turnstile)
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(define-type-alias WordCount (Hash String Int))
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(define (word-count-increment [h : WordCount]
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[word : String]
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-> WordCount)
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(hash-update/failure h
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word
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add1
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0))
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(define (count-new-words [word-count : WordCount]
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[words : (List String)]
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-> WordCount)
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(for/fold ([result word-count])
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([word words])
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(word-count-increment result word)))
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(check-type (count-new-words (hash) (list "hi" "bye"))
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: WordCount
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⇒ (hash "bye" 1 "hi" 1))
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;; OG error:
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; <pkgs>/syndicate/typed/tests/regression-count-new-words.rkt:20.4: #%app: bad syntax
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; in: (#%app word-count-increment result word)
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;; turns out I needed a #:cut in the rule for #%app (even tho it was the last
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;; syntax-parse case??)
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