ANN: GhciExt 0.6 for GHC 6.10.3

Peter Hercek phercek at
Thu May 14 17:24:40 EDT 2009


I know there were 4 unique IP addresses which checked it out. Since I do 
not know who they are I just spam this list again :)
You can get it here:
If you decide to give it a try then read the README file before installing.
It should work with the stock GHC 6.10.2 and higher, but I only tried 
briefly with GHC 6.10.3 (as it was released) and I use it without any 
problem with my customized GHC 6.10.3 (dirty support for ansi escape 
sequences in ':set prompt' for color highlighting of the prompt, patch 
for ticket (allow macros 
to redefine builtin GHCi commands), and few more details).

Here is what it does:

Prelude> :defs long
:. <file>                 -- source commands from <file>
:* <count> <cmd>...       -- run <cmd> <count> times
:x <cmd>...               -- run <cmd> with stdout suppressed
:out                      -- redirect ghci stdout back to console
:redir <var> <cmd>...     -- execute <cmd> redirecting stdout to <var>
:grep <args> < <cmd>...   -- run grep <args> on <cmd> output
 Runs grep from your OS on the output of <cmd>. This means all the options
 of your OS grep are available. '<' separates grep options from the command.
:find <cmd> [-]<var>      -- step with <cmd> until <var> is found
 Prepend variable name with '-' to disable printing of its value.
:locate <cmd> <bpArgs>    -- step with <cmd> until location <bpArgs> is hit
:bp <bpArgs>              -- put breakpoint at <bpArgs> (adds hit count)
:inject <cc> <c> <sc> <b> -- at location <b> run <c> if <cc> and stop if 
 There are two special identifiers which can be used in the breakpoint
 code (<c>) and the breakpoint stop condition (<sc>); but which are not
 usable in the breakpoint code condition (<cc>). These are:
  - ghciExt_BpId - macro name; translates to breakpoint id
  - ghciExt_HitCnt - macro name; translates to breakpoint hit count
:strobe ["<c>"] <b>       -- at location <b> show hit count if <c>
:monitor ["<c>"] <vs> <b> -- show comma-sep. variables at location <b> 
if <c>
:watch <cond> <bpArgs>    -- break at location <bpArgs> when <cond> is True
:count <N> [<bpArgs>]     -- count/stop execution at <bpArgs> or query 
bp hits
 There are three ways how to use this command:
  - :count 0 <bpArgs>  - never stops; counts hits and extends trace history
  - :count N <bpArgs>  - stops when location <bpArgs> is hit N-th time
  - :count N  - shows hit count of a ghciExt breakpoint with number N.
:hl <cmd>...              -- highlight the output of <cmd>
:defs [long]              -- list user commands (possibly with long help)
 General information for all GhciExt commands:
 - Most arguments may be in quotation marks (to allow spaces in them).
 - Instead of a regular quotation mark, @x can be used to start a string
   argument too. In such a case the argument is finished when character
   x appears again after `@x' string. Use any character in place of x.
   This was added so that one does not need to escape quotation marks
   and back-slashes in arguments (especially those representing code).

Not so much obsolete description of how it works (and how to use it) is 

Notable changes are:
* much better :grep command (you can even get color highlighted output)
* you do not need to prefix commands :main, :continute, :step, and :trace with :x any more
* :findex replaced with much better :locate

It works on linux. The only reason I recall it would not work on windows is the use of '/dev/null'. But I never tried on windows.


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