Character replacement is possible using standard transformation rules. As an example, output strings can be compacted using AssignReplace->{" "->" "} and this is the default for FortranAssign. The advantage is a reduction in the number of lines of code needed to represent an expression, which makes line-breaking more efficient. This technique can be used to substitute for other strings, such as to replace generic function types.
In[4]:= FortranAssign[Sin[x],AssignReplace->{"sin"->"dsin"}]
Out[4]//OutputForm=
dsin(x)
The replacement is literal in the sense that exact character sequences are substituted
and should be used with caution. In this example an ANSI FORTRAN function is not
obtained.
In[5]:= FortranAssign[ArcSin[x],AssignReplace->{"sin"->"dsin"}]
Out[5]//OutputForm=
adsin(x)