Opened 8 years ago

Closed 8 years ago

Last modified 7 years ago

#1354 closed bug (duplicate)

Interactive I/O with ghc doesn't prompt until after reading

Reported by: ok@… Owned by:
Priority: normal Milestone:
Component: Prelude Version: 6.2
Keywords: interactive stdio late prompt Cc:
Operating System: Unknown/Multiple Architecture: Unknown/Multiple
Type of failure: Test Case:
Blocked By: Blocking:
Related Tickets: Differential Revisions:

Description

My students complained that the interactive program they were to write using Haskell would not issue its first prompt until after the first line of input had been entered. I enclose a tiny Haskell program that exhibits this behaviour in 6.2 (SPARC Solaris) and 6.4 (Intel Linux) and am told that it also happens in 6.6. I also show that it works fine in Hugs, HBC, and NCH98. Script started on Tue 15 May 2007 02:11:26 PM NZST f% cat -n kcl.hs

1 main = 2 putStr "Enter a line:" >> 3 putChar ' ' >> 4 getLine >>= \a -> 5 putStrLn a >> 6 putStrLn a

f% uname -a SunOS frege 5.9 Generic_112233-04 sun4u sparc SUNW,Sun-Blade-100

f% hugs98 [snip]

Version: February 2001 _

Haskell 98 mode: Restart with command line option -98 to enable extensions Reading file "/home/users/okeefe_r/quasar/hugs98/shared/hugs/lib/Prelude.hs": [snip] Prelude> :load kcl Reading file "kcl.hs":

[snip] kcl.hs Main> main Enter a line: Foo! Foo! Foo!

Main> [Leaving Hugs]

f% rm a.out f% nhc98 -o a.out kcl.hs f% a.out Enter a line: Foo! Foo! Foo!

f% rm a.out f% hbc -o a.out kcl.hs f% a.out Enter a line: Foo! Foo! Foo!

f% rm a.out f% ghc --version The Glorious Glasgow Haskell Compilation System, version 6.2 f% ghc kcl.hs f% a.out Foo! Enter a line: Foo! Foo!

f% ftp kcl.hs to bling? f% ssh bling [snip] b% uname -a Linux oucs816.otago.ac.nz 2.6.19-1.2911.fc6 #1 SMP Sat Feb 10 15:51:47 EST 2007 i686 i686 i386 GNU/Linux b% hugs b% hugs [snip]

Version: November 2002 _

[snip] Prelude> :load kcl Reading file "kcl.hs":

Hugs session for: /usr/local/lib/hugs/lib/Prelude.hs kcl.hs Main> main Enter a line: Bar! Bar! Bar!

Main> [Leaving Hugs]

b% rm a.out b% ghc --version The Glorious Glasgow Haskell Compilation System, version 6.4 b% ghc kcl.hs b% ./a.out Bar! Enter a line: Bar! Bar!

Change History (3)

comment:1 Changed 8 years ago by simonmar

  • Resolution set to duplicate
  • Status changed from new to closed

dup of #1355

comment:2 Changed 7 years ago by simonmar

  • Architecture changed from Multiple to Unknown/Multiple

comment:3 Changed 7 years ago by simonmar

  • Operating System changed from Multiple to Unknown/Multiple
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