Une scientifique propose un nouveau langage de programmation pour enseigner aux enfants le codage informatique

Au travers d'une approche graduelle implémentée en Python sur 13 paliers

Une scientifique propose un nouveau langage de programmation pour enseigner aux enfants le codage informatique
Au travers d’une approche graduelle implémentée en Python sur 13 paliers

L’une des barrières les plus importantes à l’accès à la filière de la programmation informatique pour les débutants est la syntaxe des langages dont on fait usage. La nécessité de sa prise en compte met très vite le novice face à des problèmes de pure implémentation. C’est pour contourner cette difficulté que le Conseil supérieur des programmes de France a proposé Python comme langage officiel de l’enseignement de la programmation. Motif : le langage est simple d’usage et concis. Hedy, un nouveau langage de programmation, fait encore plus simple pour faciliter l’apprentissage du codage informatique aux enfants : il propose d'apprendre la programmation en parcourant 13 paliers d'un langage très proche de Python.

Le langage de programmation proposé par la scientifique Felienne Hermans est implémenté en Python. L’auteur s’appuie sur un outil d’analyse syntaxique dénommé Lark. Le code Hedy (c’est le nom du langage) est analysé par ce dernier et transpilé dans le langage de la création de Guido Van Rossum. De façon ramassée, faire référence à Hedy c’est toucher à Python, la précision étant que le premier propose plusieurs niveaux de difficultés du deuxième aux apprenants.

« Hedy est un langage de programmation graduel destiné à l'enseignement de la programmation et à l'apprentissage de Python. Il enseigne en utilisant différents niveaux. Le premier propose simplement d'imprimer du texte et de demander des entrées. Ce niveau est destiné à introduire les apprenants à l'idée d'un langage de programmation ainsi qu'à l'environnement. À partir de là, Hedy se développe pour inclure une syntaxe plus complexe et des concepts supplémentaires », commentaire l’auteur. Illustration avec le contenu grammatical mis à la disposition des apprenants au premier niveau de l’apprentissage :



Grosso modo, le langage Hedy vient renforcer l’idée selon laquelle la programmation informatique ferait plus appel à des qualités linguistiques qu’aux compétences en mathématiques. Une autre étude parue plus tôt dans l’année est à nouveau venue le mettre en avant.

« C'est parce que l’écriture du code informatique implique également l'apprentissage d'une seconde langue, la capacité d'apprendre le vocabulaire et la grammaire de cette langue et la façon dont ils travaillent ensemble pour communiquer des idées et des intentions. La recherche décrite ici est motivée par un changement de paradigme conceptuel, à savoir que l'apprentissage des langages de programmation modernes ressemble à l'apprentissage d'une langue naturelle, comme le français ou le chinois, à l'âge adulte. De façon plus précise, nous soutenons que la recherche sur les bases neurocognitives de l'aptitude à la programmation a largement omis le fait que les langages de programmation informatique sont conçus pour ressembler à la structure de communication du programmeur (les langages humains) », expliquaient les chercheurs.

La série de conclusions de cette étude résultait d’une batterie de tests centrés autour du langage Python. Les chercheurs y avaient soumis une trentaine d’adultes n’ayant jamais appris à coder, ce, pour évaluer leurs compétences cognitives sur divers axes (compétences mathématiques, linguistiques, attention, résolution de problèmes, mémoire...). Il en était ressorti que ceux qui ont appris Python le plus rapidement et avec une grande précision sont ceux qui possèdent un mélange de fortes capacités de résolution de problèmes et d’apprentissage de langues étrangères. Felienne Hermans s’étend en explications sur ce lien entre apprentissage des langues et apprentissage de la programmation informatique dans le cadre d’une présentation lors de l’édition 2020 de la conférence internationale de recherche sur l’enseignement de l’informatique. Les contenus proposés suggèrent que l’on gagnerait à mettre sur pied des moyens d’apprentissage comme Hedy pour amener plus d’enfants à choisir la filière programmation informatique plus tard.


Hedy est téléchargeable avec en sus la possibilité de l’associer à un environnement de développement intégré. L’on a également la possibilité de programmer en Hedy via une interface dans le navigateur

[CODE=Python]from lark import Lark
from lark.exceptions import VisitError, LarkError
from lark import Tree, Transformer, Visitor
from lark.indenter import Indenter

reserved_words = ['and','except','lambda','with','as','finally','nonlocal','while','assert','false','None','yield','break','for','not','class','from','or','continue','global','pass','def','if','raise','del','import','return','elif','in','True','else','is','try']

def closest_command(command, commands):
#simple string distance, could be more sophisticated MACHINE LEARNING!
min = 1000
min_command = ''
for c in commands:
min_c = minimum_distance(c, command)
if min_c < min:
min = min_c
min_command = c
return min_command

def minimum_distance(s1, s2):
if len(s1) > len(s2):
s1, s2 = s2, s1
distances = range(len(s1) + 1)
for index2, char2 in enumerate(s2):
new_distances = [index2 + 1]
for index1, char1 in enumerate(s1):
if char1 == char2:
new_distances.append(distances[index1])
else:
new_distances.append(1 + min((distances[index1], distances[index1 + 1], new_distances[-1])))
distances = new_distances
return distances[-1]

class HedyException(Exception):
def __init__(self, message, **arguments):
self.error_code = message
self.arguments = arguments

class ExtractAST(Transformer):
# simplyfies the tree: f.e. flattens arguments of text, var and punctuation for further processing
def text(self, args):
return Tree('text', [''.join([str(c) for c in args])])

#level 2
def var(self, args):
return Tree('var', [''.join([str(c) for c in args])])
def punctuation(self, args):
return Tree('punctuation', [''.join([str(c) for c in args])])
def index(self, args):
return ''.join([str(c) for c in args])
def list_access(self, args):
if type(args[1]) == Tree:
return Tree('list_access', [args[0], 'random'])
else:
return Tree('list_access', [args[0], args[1]])

#level 5
def number(self, args):
return Tree('number', ''.join([str(c) for c in args]))
#level 6 (and up)
def indent(self, args):
return ''
def dedent(self, args):
return ''

def flatten(args):
flattened_args = []
if isinstance(args, str):
return args
elif isinstance(args, Tree):
return args
else:
for a in args:
if type(a) is list:
for x in a:
flattened_args.append(flatten(x))
else:
flattened_args.append(a)
return flattened_args

class AllAssignmentCommands(Transformer):
# returns only variable assignments AND places where variables are accessed
# so these can be excluded when printing

def program(self, args):
return flatten(args)

def repeat(self, args):
commands = args[1:]
return flatten(commands)

def command(self, args):
return flatten(args)

def ask(self, args):
#todo: this also uses this arg for level 1, where it should not be used
#(since then it has no var as 1st argument)
#we should actually loop the level in here to distinguish on
return args[0].children
def assign(self, args):
return args[0].children
def assign_list(self, args):
return args[0].children
def list_access_var(self, args):
return args[0].children
def var_access(self,args):
return args[0].children

#list access is accessing a variable, so must be escaped
def list_access(self, args):
listname = args[0].children[0]
if args[1] == 'random':
return 'random.choice(' + listname + ')'
else:
return listname + '[' + args[1] + ']'
def print(self, args):
return args

def create_parser(level):
with open(f"grammars/level{str(level)}.txt", "r") as file:
grammar = file.read()
return Lark(grammar)

def all_arguments_true(args):
bool_arguments = [x[0] for x in args]
arguments_of_false_nodes = [x[1] for x in args if not x[0]]
return all(bool_arguments), arguments_of_false_nodes

# this class contains code shared between IsValid and IsComplete, which are quite similar
# because both filter out some types of 'wrong' nodes
class Filter(Transformer):
def program(self, args):
bool_arguments = [x[0] for x in args]
if all(bool_arguments):
return [True] #all complete
else:
command_num = 1
for a in args:
if not a[0]:
return False, a[1], command_num
command_num += 1

def command(self, args):
return all_arguments_true(args)

def assign(self, args):
return all_arguments_true(args)
def assign_list(self, args):
return all_arguments_true(args)
def assign_sum(self, args):
return all_arguments_true(args)
def list_access(self, args):
return all_arguments_true(args)

# level 4 commands
def list_access_var(self, args):
return all_arguments_true(args)
def ifs(self, args):
return all_arguments_true(args)
def ifelse(self, args):
return all_arguments_true(args)
def condition(self, args):
return all_arguments_true(args)
def equality_check(self, args):
return all_arguments_true(args)
def in_list_check(self, args):
return all_arguments_true(args)

# level 5 command
def repeat(self, args):
return all_arguments_true(args)

# level 6
def addition(self, args):
return all_arguments_true(args)
def substraction(self, args):
return all_arguments_true(args)
def multiplication(self, args):
return all_arguments_true(args)
def division(self, args):
return all_arguments_true(args)

#leafs are treated differently, they are True + their arguments flattened
def random(self, args):
return True, 'random'
def index(self, args):
return True, ''.join([str(c) for c in args])
def punctuation(self, args):
return True, ''.join([c for c in args])
def number(self, args):
return True, ''.join([c for c in args])
def invalid(self, args):
# return the first argument to place in the error message
# TODO: this will not work for misspelling 'at', needs to be improved!
return False, args[0][1]

class IsValid(Filter):
# all rules are valid except for the invalid production rule
# this function is used to generate more informative error messages
# tree is transformed to a node of [Bool, args, linenumber]

#would be lovely if there was some sort of default rule! Not sure Lark supports that

def ask(self, args):
return all_arguments_true(args)
def print(self, args):
return all_arguments_true(args)
def echo(self, args):
return all_arguments_true(args)

#leafs with tokens need to be all true
def var(self, args):
return all(args), ''.join([c for c in args])
def text(self, args):
return all(args), ''.join([c for c in args])
def addition(self, args):
return all(args), ''.join([c for c in args])

def invalid_space(self, args):
# return space to indicate that line start in a space
return False, " "

class IsComplete(Filter):
# print, ask an echo can miss arguments and then are not complete
# used to generate more informative error messages
# tree is transformed to a node of [True] or [False, args, line_number]

#would be lovely if there was some sort of default rule! Not sure Lark supports that

def ask(self, args):
return args != [], 'ask'
def print(self, args):
return args != [], 'print'
def echo(self, args):
#echo may miss an argument
return True, 'echo'

#leafs with tokens need to be all true
def var(self, args):
return all(args), ''.join([c for c in args])
def text(self, args):
return all(args), ''.join([c for c in args])
def addition(self, args):
return all(args), ''.join([c for c in args])

class ConvertToPython_1(Transformer):
def __init__(self, punctuation_symbols, lookup):
self.punctuation_symbols = punctuation_symbols
self.lookup = lookup

def program(self, args):
return '\n'.join([str(c) for c in args])
def command(self, args):
return args
def text(self, args):
return ''.join([str(c) for c in args])
def print(self, args):
return "print('" + args[0] + "')"
def echo(self, args):
all_parameters = ["'" + a + "'+" for a in args]
return "print(" + ''.join(all_parameters) + "answer)"
def ask(self, args):
all_parameters = ["'" + a + "'" for a in args]
return 'answer = input(' + '+'.join(all_parameters) + ")"

def wrap_non_var_in_quotes(argument, lookup):
if argument in lookup:
return argument
else:
return "'" + argument + "'"

class ConvertToPython_2(ConvertToPython_1):
def punctuation(self, args):
return ''.join([str(c) for c in args])
def var(self, args):
name = ''.join(args)
return "_" + name if name in reserved_words else name
def print(self, args):
all_arguments_converted = []
i = 0
for argument in args:
if i == len(args)-1 or args[i+1] in self.punctuation_symbols:
space = ''
else:
space = "+' '"
all_arguments_converted.append(wrap_non_var_in_quotes(argument, self.lookup) + space)
i = i + 1
return 'print(' + '+'.join(all_arguments_converted) + ')'
def ask(self, args):
var = args[0]
all_parameters = ["'" + a + "'" for a in args[1:]]
return f'{var} = input(' + '+'.join(all_parameters) + ")"
def assign(self, args):
parameter = args[0]
value = args[1]
return parameter + " = '" + value + "'"
def assign_list(self, args):
parameter = args[0]
values = ["'" + a + "'" for a in args[1:]]
return parameter + " = [" + ", ".join(values) + "]"

def list_access(self, args):
if args[1] == 'random':
return 'random.choice(' + args[0] + ')'
else:
return args[0] + '[' + args[1] + ']'

#TODO: lookuptable and punctuation chars not be needed for level2 and up anymore, could be removed
class ConvertToPython_3(ConvertToPython_2):
def text(self, args):
return ''.join([str(c) for c in args])
def print(self, args):
#opzoeken is nu niet meer nodig
return "print(" + '+'.join(args) + ')'

def indent(s):
lines = s.split('\n')
return '\n'.join([' ' + l for l in lines])

class ConvertToPython_4(ConvertToPython_3):
def list_access_var(self, args):
var = args[0]
if args[2].data == 'random':
return var + '=random.choice(' + args[1] + ')'
else:
return var + '=' + args[1] + '[' + args[2].children[0] + ']'
def ifs(self, args):
return f"""if {args[0]}:
{indent(args[1])}"""
def ifelse(self, args):
return f"""if {args[0]}:
{indent(args[1])}
else:
{indent(args[2])}"""
def condition(self, args):
return ' and '.join(args)
def equality_check(self, args):
arg0 = wrap_non_var_in_quotes(args[0], self.lookup)
arg1 = wrap_non_var_in_quotes(args[1], self.lookup)
return f"{arg0} == {arg1}" #no and statements
def in_list_check(self, args):
arg0 = wrap_non_var_in_quotes(args[0], self.lookup)
arg1 = wrap_non_var_in_quotes(args[1], self.lookup)
return f"{arg0} in {arg1}"

class ConvertToPython_5(ConvertToPython_4):
def number(self, args):
return ''.join(args)

def repeat(self, args):
times = wrap_non_var_in_quotes(args[0], self.lookup)
command = args[1]
return f"""for i in range(int({str(times)})):
{indent(command)}"""

class ConvertToPython_6(ConvertToPython_5):

def print(self, args):
#force all to be printed as strings (since there can not be int arguments)
args_new = []
for a in args:
if type(a) is Tree:
args_new.append(f'str({a.children})')
elif "'" not in a:
args_new.append(f'str({a})')
else:
args_new.append(a)

return "print(" + '+'.join(args_new) + ')'

#we can now have ints as types so chck must force str
def equality_check(self, args):
arg0 = wrap_non_var_in_quotes(args[0], self.lookup)
arg1 = wrap_non_var_in_quotes(args[1], self.lookup)
if len(args) == 2:
return f"str({arg0}) == str({arg1})" #no and statements
else:
return f"str({arg0}) == str({arg1}) and {args[2]}"

def assign(self, args):
if len(args) == 2:
parameter = args[0]
value = args[1]
if type(value) is Tree:
return parameter + " = " + value.children
else:
return parameter + " = '" + value + "'"
else:
parameter = args[0]
values = args[1:]
return parameter + " = [" + ", ".join(values) + "]"

def addition(self, args):
return Tree('sum', f'int({str(args[0])}) + int({str(args[1])})')

def substraction(self, args):
return Tree('sum', f'int({str(args[0])}) - int({str(args[1])})')

def multiplication(self, args):
return Tree('sum', f'int({str(args[0])}) * int({str(args[1])})')

def division(self, args):
return Tree('sum', f'int({str(args[0])}) // int({str(args[1])})')

class ConvertToPython_7(ConvertToPython_6):
def __init__(self, punctuation_symbols, lookup, indent_level):
self.punctuation_symbols = punctuation_symbols
self.lookup = lookup
self.indent_level = indent_level

def indent(self, args):
self.indent_level += 1
return ""

def dedent(self, args):
self.indent_level -= 1
return ""

def command(self, args):
return "".join([self.indent_level * " " + x for x in args if x != ""])

def repeat(self, args):
args = [a for a in args if a != ""] # filter out in|dedent tokens
return "for i in range(int(" + str(args[0]) + ")):\n" + "\n".join(args[1:])

def ifs(self, args):
args = [a for a in args if a != ""] # filter out in|dedent tokens
return "if " + args[0] + ":\n" + "\n".join(args[1:])

def elses(self, args):
args = [a for a in args if a != ""] # filter out in|dedent tokens
return "\nelse:\n" + "\n".join(args)

def assign(self, args): #TODO: needs to be merged with 6, when 6 is improved to with printing exprestions directly
if len(args) == 2:
parameter = args[0]
value = args[1]
if type(value) is Tree:
return parameter + " = " + value.children
else:
if "'" in value or 'random.choice' in value: #TODO: should be a call to wrap nonvarargument is quotes!
return parameter + " = " + value
else:
return parameter + " = '" + value + "'"
else:
parameter = args[0]
values = args[1:]
return parameter + " = [" + ", ".join(values) + "]"

def var_access(self, args):
if len(args) == 1: #accessing a var
return wrap_non_var_in_quotes(args[0], self.lookup)
# this was used to produce better error messages, but needs more work
# (because plain text strings are now also var_access and not textwithoutspaces
# since we no longer have priority rules
# if args[0] in self.lookup:
# return args[0]
# else:
# raise HedyException('VarUndefined', level=7, name=args[0])
else:
# dit was list_access
return args[0] + "[" + str(args[1]) + "]" if type(args[1]) is not Tree else "random.choice(" + str(args[0]) + ")"

class ConvertToPython(Transformer):

def start(self, args):
return "".join(args)

def statement(self, args):
return "".join([self.indent_level * "\t" + x + ("\n" if x[-1] != '\n' else "") for x in args if x != ""])

def if_statement(self, args):
return "if " + args[0] + ":\n" + "".join(args[1:])

def elif_statement(self, args):
return "elif " + args[0] + ":\n" + "".join(args[1:])

def else_statement(self, args):
return "else:\n" + "".join(args)

def repeat(self, args):
return "for i in range(" +args[0] + "):\n" + "".join(args[1:])

def ranged_loop(self, args):
return "for " + args[0] + " in range(" + args[1] + "," + args[2] + "):\n" + "".join(args[3:])

def assignment(self, args):
return args[0] + "=" + str(args[1])

# for now. expressions to Bool are not implemented (not sure we'd need them until 13)
# def eq(self, args):
# return str(args[0]) + "==" + str(args[1])
#
# def ne(self, args):
# return str(args[0]) + "!=" + str(args[1])
#
# def le(self, args):
# return str(args[0]) + "<=" + str(args[1])
#
# def ge(self, args):
# return str(args[0]) + ">=" + str(args[1])
#
# def lt(self, args):
# return str(args[0]) + "<" + str(args[1])
#
# def gt(self, args):
# return str(args[0]) + ">" + str(args[1])

# migrated to level 6
# def addition(self, args):
# return str(args[0]) + "+" + str(args[1])
#
# def substraction(self, args):
# return str(args[0]) + "-" + str(args[1])
#
# def multiplication(self, args):
# return str(args[0]) + "*" + str(args[1])
#
# def division(self, args):
# return str(args[0]) + "/" + str(args[1])

def list(self, args):
return str(args)

def list_access(self, args):
return args[0] + "[" + str(args[1]) + "]" if args[1] != "random" else "random.choice(" + str(args[0]) + ")"

def function_call(self, args):
return args[0] + "(" + ", ".join(args[1:]) + ")"

def INTEGER(self, args):
return int(args.value)

def FLOAT(self, args):
return float(args.value)

def NAME(self, args):
return str(args.value)

def STRING(self, args):
return args.value

def INDENT(self, args):
self.indent_level += 1
return ""

def DEDENT(self, args):
self.indent_level -= 1
return ""

class BasicIndenter(Indenter):
NL_type = "_EOL"
OPEN_PAREN_types = []
CLOSE_PAREN_types = []
INDENT_type = "INDENT"
DEDENT_type = "DEDENT"
tab_len = 4

def create_grammar(level):
with open("grammars/level" + str(level) + ".txt", "r") as file:
return file.read()

def transpile(input_string, level):
try:
return transpile_inner(input_string, level)
except Exception as E:
#we retry HedyExceptions of the type Parse (and Lark Errors) but we raise Invalids
if E.args[0] == 'Parse':
#try 1 level lower
if level > 1:
try:
new_level = level-1
result = transpile_inner(input_string, level-1)
raise HedyException('Wrong Level', correct_code = result, original_level=level, working_level=new_level)
except LarkError as e:
raise HedyException('Parse', level=level, parse_error=e.args[0])
else:
raise E
else:
raise E

def repair(input_string):
#the only repair we can do now is remove leading spaces, more can be added!
return '\n'.join([x.lstrip() for x in input_string.split('\n')])

def transpile_inner(input_string, level):
if level <= 6:
punctuation_symbols = ['!', '?', '.']
level = int(level)
parser = Lark(create_grammar(level))

try:
program_root = parser.parse(input_string+ '\n').children[0] # getting rid of the root could also be done in the transformer would be nicer
abstract_syntaxtree = ExtractAST().transform(program_root)
lookup_table = AllAssignmentCommands().transform(abstract_syntaxtree)

except Exception as e:
# TODO: if all else fails, here we[/0]...