Skip to main content

ocaml random string and word generation


I had to insert sample data in a database:

  • Users
    • username
    • enabled
  • Products
    • name
    • description
    • price
All should be random, and to "benchmark" the rendering (HTML/CSS), I must make the effort to have different text and number length. I decide to generate the sample data with OCaml.

Random Int

Generate a random integer between 1 and 1000 and return it as a string:

         let rand_price () = string_of_int (1+ ( 999)) ;;        

Random Char

Generate a random lowercase character (between 'a' and 'z'). 'a' ASCII code is 97 and the 26 following letters are the 26 following numbers:

              let rand_chr () = (Char.chr (97 + ( 26)));;        

Random vowel

Generate a random character until it matches a vowel. Please add a comment if you would suggest another algorithm:

              let rec rand_voy () =          let got = (rand_chr ())           in            match got with              | 'a' | 'e' | 'i' | 'o' | 'u' | 'y' ->  got              | _ -> rand_voy ();;        

Random consonant

Generate a random character until it doesnt matche a vowel. Please add a comment if you would suggest another algorithm:

         let rec rand_con () =            let got = (rand_chr ())             in              match got with                | 'a' | 'e' | 'i' | 'o' | 'u' | 'y' ->  rand_con ()               | _ -> got ;;        

Random syllable(s)

In this document, a syllable is a consonant followed by a vowel. Generate a finite number of random syllables:

         let rec rand_convoy acc syll_number () =           match syll_number with              | 0 -> acc;             | _ -> rand_convoy (acc ^ (Char.escaped (rand_con ())) ^ (Char.escaped(rand_voy()))) (syll_number - 1) ();;        
The final goal is to use all this as a "string", so we make "char" to "string" conversion at this level with the "Char.escaped" function.

Random short word

Short word: between 3 and 6 syllables.

         (* mot: entre 3 et 6 syllabes *)         let rand_word () = (rand_convoy "" (3 + ( 3)) ());;        
Wel will also need a fixed length word, of 4 syllables.
           (* nom: 4 syllabes c'est tout *)         let rand_name () = rand_convoy "" 3 ();;        

Random sentence

Random sentence is a random number of random words. We will limit the number of words (to avoid bloating the database). Wel will end the sentences with a ".".

         let rec rand_sentence acc word_number () =           match word_number with              | 0 ->               (acc ^ (rand_word ()) ^ ".");             | _ -> rand_sentence (acc ^ (rand_word ()) ^ " ") (word_number - 1) ();;        


Generate a "description", and quote a string in preparation for INSERT in the database:

         let rand_description () = rand_sentence "" (10 + ( 10))  ();;         let sql_quote a_string = "'"^a_string^"'";;         let generate_insert_user () = "INSERT INTO users VALUES ("^sql_quote (rand_name ())^" ,1)" ;;         let generate_insert_product p_id  =            "INSERT INTO products VALUES ("^(string_of_int p_id)^", '"^(rand_name ())^"', '"^(rand_description ())^"', "^(rand_price ())^")";;        

SQLite filling

SQLite manipulation has already been introduced in another post.

         let db = Sqlite3.db_open "/var/www/database.db";;          Sqlite3.exec db (generate_insert_user ());;         let rec fill_users number =            match number with              | 0 -> ()             | _ ->                Sqlite3.exec db (generate_insert_user ()) ;                fill_users (number-1);                ();;                  let rec fill_products number =             match number with              | 0 -> ()             | _ ->                Sqlite3.exec db (generate_insert_product number) ;                fill_products (number-1);                ();;        

Popular posts from this blog

npm run build base-href

Using NPM to specify base-href When building an Angular application, people usually use "ng" and pass arguments to that invocation. Typically, when wanting to hard code "base-href" in "index.html", one will issue: ng build --base-href='' I used to build my angular apps through Bamboo or Jenkins and they have a "npm" plugin. I got the habit to build the application with "npm run build" before deploying it. But the development team once asked me to set the "--base-href=''" parameter. npm run build --base-href=' did not set the base href in indext.html After looking for a while, I found where it says: You need to use −− to pass arguments to npm scripts. This did the job! The command to issue is then: npm run build -- --base-href='

Jenkins invalid privatekey

Publish over SSH, Message "invalid privatekey:" With quite recent (June-July 2020) installations of Jenkins and OpenSSH, I have the following error message when using the "Deploy overs SSH" Jenkins plug-in and publishing artifacts to the target overs SSH: jenkins.plugins.publish_over.BapPublisherException: Failed to add SSH key. Message [invalid privatekey: [B@d8d395a] This problem seems to be referenced here: Just regenerate a key with the right parameters To solve it: ssh-keygen -t rsa -b 4096 Or ssh-keygen -t rsa -b 4096 -m PEM

Emacs Pulumi LSP

Install Pulumi Emacs Mode The source code is on At the very bottom of the page are the instructions on how to install. You Need to have make installed. $ make install emacs-client mkdir -p ./bin go build -ldflags "-X" -o ./bin -p 10 ./cmd/... go: downloading v3.53.1 ... ... ... go install -ldflags "-X" ./cmd/... mkdir -p editors/emacs/bin cd editors/emacs && emacs -Q --batch --eval "(progn (setq package-user-dir \"$(pwd)/bin\" \ package-archives '((\"melpa\" . \"\") \