Haskell 增加「；宽度“；ghci公司

当GHCI中的输出线过长时，会断开：

> :i bar
bar :: Lens' (Foo a0) Int   -- Defined at NewType_makeLenses.hs:7:1
> :i baz
baz :: Lens (Foo a0) (Foo a1) a0 a1
    -- Defined at NewType_makeLenses.hs:7:1

---

有没有办法设置线条的最大长度？

有三个选项可以控制

您正在寻找

-dppr cols

。其默认值为

100

。您可以在调用GHCi或使用

：set

时将其设置为任何其他值

方案比较 不带

-dppr cols

使用

-dppr-cols140

带

：设置-dppr-cols140

奖金：我是怎么找到这个的？ 我没有查看标志，而是查看了GHC的源代码：

$ git clone --depth=1 https://github.com/ghc/ghc.git && cd ghc

接下来，我查找以定义的

开头的字符串：

$ grep -C2 "\"Defined" -r . --exclude-dir=testsuite
./compiler/basicTypes/Name.hs-ppr_z_occ_name occ = ztext (zEncodeFS (occNameFS occ))
./compiler/basicTypes/Name.hs-
./compiler/basicTypes/Name.hs:-- Prints (if mod information is available) "Defined at <loc>" or
./compiler/basicTypes/Name.hs:--  "Defined in <mod>" information for a Name.
./compiler/basicTypes/Name.hs-pprDefinedAt :: Name -> SDoc
./compiler/basicTypes/Name.hs:pprDefinedAt name = text "Defined" <+> pprNameDefnLoc name
./compiler/basicTypes/Name.hs-
./compiler/basicTypes/Name.hs-pprNameDefnLoc :: Name -> SDoc

Outputable.hs
包括
printForUser
，它与
Pretty
中的
printDoc
一起使用
pprcoldflags
，定义为

printDoc :: Mode -> Int -> Handle -> Doc -> IO ()
-- printDoc adds a newline to the end
printDoc mode cols hdl doc = printDoc_ mode cols hdl (doc $$ text "")

而
pprCol
是在
compiler/main/DynFlags.hs
中定义的，它对应于
-dppr cols
。您只需通过GHC:
grep
即可。
谢谢。我的工具中包含了这个选项：）
$ ghci NewType_makeLenses.hs
[1 of 1] Compiling Main             ( NewType_makeLenses.hs, interpreted )
Ok, modules loaded: Main.
> :set -dppr-cols140
> :i bar
bar :: Lens' (Foo a0) Int       -- Defined at NewType_makeLenses.hs:9:1
> :i baz
baz :: Lens (Foo a0) (Foo a1) a0 a1     -- Defined at NewType_makeLenses.hs:10:1

$ git clone --depth=1 https://github.com/ghc/ghc.git && cd ghc

$ grep -C2 "\"Defined" -r . --exclude-dir=testsuite
./compiler/basicTypes/Name.hs-ppr_z_occ_name occ = ztext (zEncodeFS (occNameFS occ))
./compiler/basicTypes/Name.hs-
./compiler/basicTypes/Name.hs:-- Prints (if mod information is available) "Defined at <loc>" or
./compiler/basicTypes/Name.hs:--  "Defined in <mod>" information for a Name.
./compiler/basicTypes/Name.hs-pprDefinedAt :: Name -> SDoc
./compiler/basicTypes/Name.hs:pprDefinedAt name = text "Defined" <+> pprNameDefnLoc name
./compiler/basicTypes/Name.hs-
./compiler/basicTypes/Name.hs-pprNameDefnLoc :: Name -> SDoc

$ grep "data SDoc" -r . --exclude-dir=testsuite
./compiler/utils/Outputable.hs:data SDocContext = SDC
./compiler/utils/Outputable.hs-boot:data SDoc

printDoc :: Mode -> Int -> Handle -> Doc -> IO ()
-- printDoc adds a newline to the end
printDoc mode cols hdl doc = printDoc_ mode cols hdl (doc $$ text "")