Silly vertical printing of long argument lists
Summary
GHC's pretty printer does not cope well with long argument lists.
Long argument lists do exist in practice, e.g, for records: https://github.com/agda/agda/blob/83a48d27010d2c292cc42100081a24f8df573688/src/full/Agda/TypeChecking/Serialise/Instances/Errors.hs#L192-L198
Steps to reproduce
type A = Int
data D = D A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A
test :: D -> D
test (D a b c d e f g h i j k l m n o p q r s t u v w x y z aa bb cc dd ee ff gg hh ii jj kk ll mm nn)
= D a b c d e f g h i j k l m n o p q r s t u v w x y z aa bb cc dd ee ff gg hh ii jj kk ll mm nnThe compiler reports:
ManyConstructorArgs.hs:5:7: error:
• The constructor ‘D’ should have 41 arguments, but has been given 40
• In the pattern:
D a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
aa
bb
cc
dd
ee
ff
gg
hh
ii
jj
kk
ll
mm
nn
In an equation for ‘test’:
test
(D a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
aa
bb
cc
dd
ee
ff
gg
hh
ii
jj
kk
ll
mm
nn)
= D a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
x
y
z
aa
bb
cc
dd
ee
ff
gg
hh
ii
jj
kk
ll
mm
nn
|
5 | test (D a b c d e f g h i j k l m n o p q r s t u v w x y z aa bb cc dd ee ff gg hh ii jj kk ll mm nn)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^Expected behavior
Print argument list in horizontal mode and wrap it somewhere.
Environment
- GHC version used: 8.6.4