let rec fact = function
0 -> 1 | n-> n*(fact(n-1));;
 

Unfortunately, the "ocamlopt 1fact.ml" command gave me the following answer :
/tmp/camlasm29.s: Assembler messages:
/tmp/camlasm29.s:2: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:3: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:5: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:6: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:9: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:10: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:14: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:15: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:16: Warning: rest of line ignored; first ignored character is `a'
/tmp/camlasm29.s:20: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:21: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:28: Error: junk `act_fact_49' after expression
/tmp/camlasm29.s:45: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:46: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:48: Error: junk `act_1' after expression
/tmp/camlasm29.s:49: Error: junk `act' after expression
/tmp/camlasm29.s:53: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:54: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:56: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:57: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:59: Warning: rest of line ignored; first ignored character is `1'
/tmp/camlasm29.s:60: Warning: rest of line ignored; first ignored character is `1'
Assembler error, input left in file /tmp/camlasm29.s
 

I think this is due to the name of the program, 1fact.ml, which should not begin with a number, because when I renamed the file fact1.ml it worked perfectly.
Is it normal?
 

Thank you.
Sarah Djebali.