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shmibs's solution

to RNA Transcription in the OCaml Track

Published at Jan 09 2019 · 0 comments
Test suite


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

Getting Started

For installation and learning resources, refer to the exercism help page.


To work on the exercises, you will need Opam and Base. Consult opam website for instructions on how to install opam for your OS. Once opam is installed open a terminal window and run the following command to install base:

opam install base

To run the tests you will need OUnit. Install it using opam:

opam install ounit

Running Tests

A Makefile is provided with a default target to compile your solution and run the tests. At the command line, type:


Interactive Shell

utop is a command line program which allows you to run Ocaml code interactively. The easiest way to install it is via opam:

opam install utop

Consult utop for more detail.

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The exercism/ocaml repository on GitHub is the home for all of the Ocaml exercises.

If you have feedback about an exercise, or want to help implementing a new one, head over there and create an issue. We'll do our best to help you!


Rosalind http://rosalind.info/problems/rna

Submitting Incomplete Solutions

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


open Base
open OUnit2

let char_of_variant = function
  | `A -> 'A' | `C -> 'C' | `G -> 'G' | `T -> 'T' | `U -> 'U'
let printer l = List.map ~f:char_of_variant l |> String.of_char_list
let ae exp got _test_ctxt = assert_equal ~printer exp got

let tests =
  ["transcribes empty list">::
    ae [] (Rna_transcription.to_rna []);
   "transcribes cytidine">::
    ae [`G] (Rna_transcription.to_rna [`C]);
   "transcribes guanosine">::
    ae [`C] (Rna_transcription.to_rna [`G]);
   "transcribes adenosie">::
    ae [`U] (Rna_transcription.to_rna [`A]);
   "transcribes thymidine">::
    ae [`A] (Rna_transcription.to_rna [`T]);
   "transcribes multiple">::
    ae [`U; `G; `C; `A; `C; `C; `A; `G; `A; `A; `U; `U]
       (Rna_transcription.to_rna [`A; `C; `G; `T; `G; `G; `T; `C; `T; `T; `A; `A])

let () =
  run_test_tt_main ("rna-transcription tests" >::: tests)
open Core

type dna = [ `A | `C | `G | `T ]
type rna = [ `A | `C | `G | `U ]

let to_rna (dl : dna list) =
  List.map dl ~f:(function
    | `G -> `C
    | `C -> `G
    | `T -> `A
    | `A -> `U

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