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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);                ();;        

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