Gerbil IO environments

This module is useful if you need to evaluate expressions and control their IO environment.

Installation

gxpkg install github.com/thunknyc/gerbil-ioenv

Usage

begin/string-io INPUT-STRING EXPR ...

Evaluate EXPR ... in a dynamic environment where CURRENT-INPUT-PORT has been bound to a string input port initialized with INPUT-STRING and return an association list containing three keys: 'result, 'output, and 'error. The 'result key is associated with the result of the evaluation whereas the 'output and 'error keys are associated with the output to CURRENT-OUTPUT- and CURRENT-ERROR-PORT, respectively.

apply/string-io INPUT-STRING PROC ARG ... REST-ARGS

Apply ARG ... REST-ARGS to PROC in a dynamic environment where CURRENT-INPUT-PORT has been bound to a string input port initialized with INPUT-STRING and return an association list containing three keys: 'result, 'output, and 'error. The 'result key is associated with the result of the evaluation whereas the 'output and 'error keys are associated with the output to CURRENT-OUTPUT- and CURRENT-ERROR-PORT, respectively.

let-ioenv ((INPUT-PORT-NAME INPUT-PORT)
           (OUTPUT-PORT-NAME OUTPUT-PORT)
           (ERROR-PORT-NAME OUTPUT-PORT))
    (NAME BOUND-EXPR)
 EXPR ...

Bind to INPUT-PORT-NAME etc. the associated values. Evaluate BOUND-EXPR within a dynamic environment in which CURRENT-INPUT-PORT etc. have been bound to those values. Bind the resulting value to NAME and evalute EXPR ...

An example:

(let-ioenv ((in (open-input-string "(+ 1 1)"))
            (out (open-output-string))
            (err (open-output-string)))
    (val (begin (displayln (eval (read))) 'done))
  (list val (get-output-string out)))

;; => '(done "2\n")

ioenv INPUT-PORT OUTPUT-PORT ERROR-PORT

Create an IO environment.

call-with-ioenv IOENV THUNK

Bind current-input-port, current-output-port, and current-error-port parameters to the values associated with IOENV and evaluate THUNK, with zero arguments.

with-ioenv IOENV E1 E2 ...

Syntactic sugar for call-with-ioenv. Bind current-input-port, current-output-port, and current-error-port parameters to the values associated with IOENV and evaluate E1, E2, etc.

string-ioenv INPUT-STRING

Return a new IO environment, with input from a string port initialized with INPUT-STRING, and output and error associated with new string output ports.