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to RNA Transcription in the D Track

Published at May 28 2020 · 0 comments
Instructions
Test suite
Solution

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

Getting Started

Make sure you have read D page on exercism.io. This covers the basic information on setting up the development environment expected by the exercises.

Passing the Tests

Get the first test compiling, linking and passing by following the three rules of test-driven development. Create just enough structure by declaring namespaces, functions, classes, etc., to satisfy any compiler errors and get the test to fail. Then write just enough code to get the test to pass. Once you've done that, uncomment the next test by moving the following line past the next test.

static if (all_tests_enabled)

This may result in compile errors as new constructs may be invoked that you haven't yet declared or defined. Again, fix the compile errors minimally to get a failing test, then change the code minimally to pass the test, refactor your implementation for readability and expressiveness and then go on to the next test.

Try to use standard D facilities in preference to writing your own low-level algorithms or facilities by hand. DRefLanguage and DReference are references to the D language and D standard library.

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.

rna_transcription.d

module rna_transcription;

unittest
{
    import std.exception : assertThrown;

    immutable int allTestsEnabled = 0;

    // Empty RNA sequence
    assert(toRna("") == "");

    static if (allTestsEnabled)
    {
        // RNA complement of cytosine is guanine
        assert(toRna("C") == "G");

        // RNA complement of guanine is cytosine
        assert(toRna("G") == "C");

        // RNA complement of thymine is adenine
        assert(toRna("T") == "A");

        // RNA complement of adenine is uracil
        assert(toRna("A") == "U");

        // RNA complement
        assert(toRna("ACGTGGTCTTAA") == "UGCACCAGAAUU");
    }

}
module rna_transcription;

/// Given a DNA strand, return its RNA complement (per RNA transcription).
string toRna(string dna) {
    char[] rna = dna.dup;
    foreach (i, ch; rna)
    {
        switch (ch)
        {
            case 'G': rna[i] = 'C'; break;
            case 'C': rna[i] = 'G'; break;
            case 'T': rna[i] = 'A'; break;
            case 'A': rna[i] = 'U'; break;
            default:
                throw new Exception("Unexpected DNA nucleotide");
        }
    }

    return rna.idup;
}

unittest
{
    import std.exception : assertThrown;

    immutable int allTestsEnabled = 1;

    // Empty RNA sequence
    assert(toRna("") == "");

    static if (allTestsEnabled)
    {
        // RNA complement of cytosine is guanine
        assert(toRna("C") == "G");

        // RNA complement of guanine is cytosine
        assert(toRna("G") == "C");

        // RNA complement of thymine is adenine
        assert(toRna("T") == "A");

        // RNA complement of adenine is uracil
        assert(toRna("A") == "U");

        // RNA complement
        assert(toRna("ACGTGGTCTTAA") == "UGCACCAGAAUU");
    }

}

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