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marchukov's solution

to RNA Transcription in the Scheme Track

Published at Oct 06 2019 · 0 comments
Instructions
Test suite
Solution

Note:

This exercise has changed since this solution was written.

Given a DNA strand, return its RNA complement (per RNA transcription).

Both DNA and RNA strands are a sequence of nucleotides.

The four nucleotides found in DNA are adenine (A), cytosine (C), guanine (G) and thymine (T).

The four nucleotides found in RNA are adenine (A), cytosine (C), guanine (G) and uracil (U).

Given a DNA strand, its transcribed RNA strand is formed by replacing each nucleotide with its complement:

  • G -> C
  • C -> G
  • T -> A
  • A -> U

Running and testing your solutions

From the command line

Simply type make chez if you're using ChezScheme or make guile if you're using GNU Guile.

From a REPL

  • Enter test.scm at the repl prompt.
  • Develop your solution in rna-transcription.scm reloading as you go.
  • Run (test) to check your solution.

Testing options

You can see more information about failing test cases by passing arguments to the procedure test. To see the failing input and output call (test 'input 'output).

Source

Hyperphysics http://hyperphysics.phy-astr.gsu.edu/hbase/Organic/transcription.html

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

test.scm

#!r6rs

(import (rnrs))

(define test-fields '(input output who))

(define (test-run-solution solution input)
  (if (procedure? solution) (apply solution input) solution))

(define (test-success description success-predicate
         procedure input output)
  (call/cc
    (lambda (k)
      (with-exception-handler
        (lambda (e)
          (k `(fail
                (description . ,description)
                (input . ,input)
                (output . ,output)
                (who . ,procedure))))
        (lambda ()
          (let ([result (test-run-solution procedure input)])
            (unless (success-predicate result output)
              (error 'exercism-test
                "test fails"
                description
                input
                result
                output)))
          `(pass . ,description))))))

(define (test-error description procedure input)
  (call/cc
    (lambda (k)
      (with-exception-handler
        (lambda (e) (k `(pass . ,description)))
        (lambda ()
          (test-run-solution procedure input)
          `(fail
             (description . ,description)
             (input . ,input)
             (output . error)
             (who . ,procedure)))))))

(define (run-test-suite tests . query)
  (for-each
    (lambda (field)
      (unless (and (symbol? field) (memq field test-fields))
        (error 'run-test-suite
          (format #t "~a not in ~a" field test-fields))))
    query)
  (let-values ([(passes failures)
                (partition
                  (lambda (result) (eq? 'pass (car result)))
                  (map (lambda (test) (test)) tests))])
    (cond
      [(null? failures) (format #t "~%Well done!~%~%")]
      [else
       (format
         #t
         "~%Passed ~a/~a tests.~%~%The following test cases failed:~%~%"
         (length passes)
         (length tests))
       (for-each
         (lambda (failure)
           (format
             #t
             "* ~a~%"
             (cond
               [(assoc 'description (cdr failure)) => cdr]
               [else (cdr failure)]))
           (for-each
             (lambda (field)
               (let ([info (assoc field (cdr failure))])
                 (format #t "  - ~a: ~a~%" (car info) (cdr info))))
             query))
         failures)
       (error 'test "incorrect solution")])))

(define dna->rna)

(define (test . query)
  (apply
    run-test-suite
    (list
      (lambda ()
        (test-success "Empty RNA sequence" equal? dna->rna '("")
          ""))
      (lambda ()
        (test-success "RNA complement of cytosine is guanine" equal?
          dna->rna '("C") "G"))
      (lambda ()
        (test-success "RNA complement of guanine is cytosine" equal?
          dna->rna '("G") "C"))
      (lambda ()
        (test-success "RNA complement of thymine is adenine" equal?
          dna->rna '("T") "A"))
      (lambda ()
        (test-success "RNA complement of adenine is uracil" equal?
          dna->rna '("A") "U"))
      (lambda ()
        (test-success "RNA complement" equal? dna->rna
          '("ACGTGGTCTTAA") "UGCACCAGAAUU")))
    query))

(let ([args (command-line)])
  (if (null? (cdr args))
      (load "rna-transcription.scm")
      (load (cadr args)))
  (test 'input 'output))
(import (rnrs))

(define (dna->rna dna)
  (string-map (lambda (char) 
                (cond ((char=? char #\G) #\C)
                      ((char=? char #\C) #\G)
                      ((char=? char #\T) #\A)
                      ((char=? char #\A) #\U))) 
              dna))

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