The doc of getfield says getfield(*value*, *name::Symbol*)
Extract a named field from a value of composite type. The syntax a.b calls getfield(a, :b), and the syntax a.(b) calls getfield(a, b). but when I try the a.(b) variation, it errors (or it's me who errors?) julia> gmt_modules.write "<?I,>?O" julia> gmt_modules.(write) ERROR: type: getfield: expected Symbol, got Function