Argument type inference is fairly dumb, could join `String` and `codepoint` into `String

[fridis]

Take this example

# function with 3 arguments of inferred type i32, codepoint and codepoint:
#
line(l, start, end) =>
  start + "-"*l + end

line 20 "<" ">" |> say
line 10 "<<" ">>" |> say

Which produces

 > ../build/bin/fz content/tutorial/examples/value_args_example2infer_fail.fz

/home/fridi/fuzion/work/webserver/content/tutorial/examples/value_args_example2infer_fail.fz:7:9: error 1: Incompatible types when passing argument in a call
line 10 "<<" ">>" |> say

Actual type for argument #2 'start' does not match expected type.
In call to          : 'line'
expected formal type: 'codepoint'
actual type found   : 'String'
assignable to       : 'String'
for value assigned  : '"<<"'
To solve this, you could change the type of the target 'start' to 'String' or convert the type of the assigned value to 'codepoint'.


/home/fridi/fuzion/work/webserver/content/tutorial/examples/value_args_example2infer_fail.fz:7:14: error 2: Incompatible types when passing argument in a call
line 10 "<<" ">>" |> say

Actual type for argument #3 'end' does not match expected type.
In call to          : 'line'
expected formal type: 'codepoint'
actual type found   : 'String'
assignable to       : 'String'
for value assigned  : '">>"'
To solve this, you could change the type of the target 'end' to 'String' or convert the type of the assigned value to 'codepoint'.

2 errors.

while it works if the calls are swapped

# function with 3 arguments of inferred type i32, codepoint and codepoint:
#
line(l, start, end) =>
  start + "-"*l + end

line 10 "<<" ">>" |> say
line 20 "<" ">" |> say

It would be nice to either produce an error independently of the the order, or not to produce an error at all.

[michaellilltokiwa]

@fridis Just to clarify, a union of array and list would still not be Sequence but t_error, right?