Warning: This is the manual of the legacy Guile 2.0 series. You may want to read the manual of the current stable series instead.

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3.3.3 Using the Guile REPL

If you start Guile without specifying a particular program for it to execute, Guile enters its standard Read Evaluate Print Loop — or REPL for short. In this mode, Guile repeatedly reads in the next Scheme expression that the user types, evaluates it, and prints the resulting value.

The REPL is a useful mechanism for exploring the evaluation behaviour described in the previous subsection. If you type string-append, for example, the REPL replies #<primitive-procedure string-append>, illustrating the relationship between the variable string-append and the procedure value stored in that variable.

In this manual, the notation ⇒ is used to mean “evaluates to”. Wherever you see an example of the form


feel free to try it out yourself by typing expression into the REPL and checking that it gives the expected result.