scheme@(guile-user)> (define abc "hello")
scheme@(guile-user)> abc
$1 = "hello"
scheme@(guile-user)> aBc
<unknown-location>: warning: possibly unbound variable `aBc'
ERROR: In procedure module-lookup:
ERROR: Unbound variable: aBc
Entering a new prompt.  Type `,bt' for a backtrace or `,q' to continue.
scheme@(guile-user) [1]> (read-options 'help)
copy              no    Copy source code expressions.
positions         yes   Record positions of source code expressions.
case-insensitive  no    Convert symbols to lower case.
keywords          #f    Style of keyword recognition: #f, 'prefix or 'postfix.
r6rs-hex-escapes  no    Use R6RS variable-length character and string hex escapes.
square-brackets   yes   Treat `[' and `]' as parentheses, for R6RS compatibility.
hungry-eol-escapes no   In strings, consume leading whitespace after an
                        escaped end-of-line.
curly-infix       no    Support SRFI-105 curly infix expressions.
scheme@(guile-user) [1]> (read-enable 'case-insensitive)
$2 = (square-brackets keywords #f case-insensitive positions)
scheme@(guile-user) [1]> ,q
scheme@(guile-user)> aBc
$3 = "hello"