website/content/blog/2024-04-13-sly-repl-io-issues.md

+++
title = "Issue with SBCL console output in Sly"
date = 2024-04-13
[taxonomies]
tags = ["programming"]
categories = ["lisp"]
+++

# Inconsistent output in REPL

When doing the examples in the _Practical Common Lisp_ book I had confusing output in the repl when prompting the user for CDs using SBCL.

```
; Dedicated output stream setup (port 46185)
; Redirecting all output to this MREPL
; SLY 1.0.43 (#<MREPL mrepl-1-1>)
CL-USER> (prompt-for-cd)
Title: Unplugged
Eric Clapton 
8
y
```

Apparently a similar issue was first found on MacOSX and later confirmed on Arch.

The suggestion was given to disable passing the output via a socket to have higher performance that via the protocol by adding

```
(setf slynk:*use-dedicated-output-stream* nil)
```

Since I rather have something working than it being highly performant and not-working I followed the suggestion which fixed the issue:


```
CL-USER> (prompt-for-cd)
Title: Bar 
Artist: Foo Fighters
Rating: 8
Ripped: y

y (y or n) y
(:TITLE "Bar " :ARTIST "Foo Fighters" :RATING 8 :RIPPED T)
CL-USER>  
```

so I can continue with the chapter.