Python syntax¶
prometeo is an embedded domain specific language based on Python. Hence, its syntax is based on Python. Below you find details regarding the most common supported Python constructs that prometeo is able to transpile to C.
variable declaration¶
A variable can be declared as follows
<var_name> : <type> = <value>
where <var_name> must be a valid identifier <type> must be a valid prometeo built-in type or a user-defined type and <value> must be an valid expression of type <type>.
Example:
a : int = 1
Notice that, unlike in Python, type hints are strictly mandatory as they will instruct prometeo’s parser regarding the type of the variables being defined.
for loop¶
A for loop takes the form
for i in range([<start>], <end>)
...
where the optional parameter <start> must be an expression of type int (default value 0) and defines the starting value of the loop’s index and <end> must be an expression of type <int> which defines its final value.
function definition¶
Functions can be defined as follows
def <function_name> (<arg1> : <arg_1_type>, ...) -> <ret_type> :
...
return <ret_value>
class definition¶
prometeo supports basic classes of the following form
class <name>:
def __init__(self, <arg1> : <arg_1_type>, ...) -> None:
self.<attribute> : <type> = <value>
...
def <method_name> (self, <arg1> : <arg_1_type>, ...) -> <ret_type>:
...
return <ret_value>
main function¶
For consistency all main functions need to be defined as follows
def main() -> int:
...
return 0
pure Python blocks¶
In order to be able to use the full potential of the Python language and its vast pool of libraries, it is possible to write pure Python blocks that are run only when prometeo code is executed directly from the Python intepreter (when –cgen is set to false). In particular, any line that is enclosed within # pure > and # pure < will be run only by the Python interpreter, but completely discarded by prometeo’s parser.
# some prometeo code
A : pmat = pmat(n,n)
...
# pure >
# this is only run by the Python interpreter (--cgen=False)
# and will not be transpiled)
# some Python code
import numpy as np
M = np.array([[1.0, 2.0],[0.0, 0.5]])
print(np.linalg.eigvals(M))
...
# pure <
# some more prometeo code
for i in range(n):
for j in range(n):
A[i, j] = 1.0
...