This project provides an interactive environment for evaluating go expressions.

Yeah, we know of some others. I think this one has more promise. The heavy lifting for eval is provided by the Carl Chatfield's eval package.

• Make sure our Go environment is setup, e.g. $GOBIN, $GOPATH, ...
• Make sure you have a version 1.2ish Go installed.

   $ go get github.com/rocky/go-fish
   $ cd $GOPATH/src/github.com/rocky/go-fish
   $ make install  # or look at Makefile

If you have go-gnureadline installed and want the GNU readline support. In addition to the above try:

   $ make go-fish-grl
   $ make install

If you have remake installed, you can change make above to remake -x to see the simple go and shell commands that get run. (And remake --tasks is also your friend.)

Run go-fish or go-fish-grl. For now, we have only a static environment provided and that's exactly the environment that go-fish uses for itself. (In other words this is ideally suited to introspect about itself). Since it uses eval and that package is a reasonable size program, many of the packages like os, fmt, strconv, errors, exec, etc. are available. Look at the import list in file repl_imports.go for the exact list, or type pkgs inside go-fish (as shown below) for a list.

Two global variables have been defined: env, and results. env the environment that is defined, again largely by eval_imports.go. As you enter expresions, the results are saved in slice results. To quit, enter Ctrl-D (EOF) or the word quit.

Here's a sample session:

$ ./go-fish
== A simple Go eval REPL ==

Results of expression are stored in variable slice "results".
The environment is stored in global variable "env".

Enter expressions to be evaluated at the "gofish>" prompt.

To see all results, type: "results".

To quit, enter: "quit" or Ctrl-D (EOF).
To get help, enter: "help".
gofish> 10+len("abc" + "def")
Kind = Type = int
results[0] = 16
gofish> os.Stderr
os.Stderr
Kind = ptr
Type = *os.File
results[1] = &{0x1882d120}
gofish> fmt.Fprintln(os.Stderr, os.Getenv("GOPATH"))
/home/rocky/go
Kind = Multi-Value
15, nil
gofish> help *
All command names:
help  packages  quit
gofish> packages
All imported packages:
ansi    binary  eval      fmt     math    rand     scanner  sync       time   
ast     bufio   exec      io      os      reflect  sort     syscall    token  
atomic  bytes   filepath  ioutil  parser  repl     strconv  tabwriter  unicode
big     errors  flag      log     pprof   runtime  strings  testing    utf8  
gofish> pkg ansi
=== Package ansi ("github.com/mgutz/ansi"): ===
Constants of ansi:
  Reset
Functions of ansi:
  Color  ColorCode  ColorFunc  DisableColors
gofish> quit
go-fish: That's all folks...
$ 

• What's left to do?
• go-play: A locally-run HTML5 web interface for experimenting with Go code
• gub: A Go debugger based on the SSA interpreter