cond-thunk

1 files changed, 58 insertions, 0 deletions

diff --git a/doc/mcgoron.cond-thunk.scm b/doc/mcgoron.cond-thunk.scm
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+++ b/doc/mcgoron.cond-thunk.scm
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+(((name . "cond-thunk")
+  (signature syntax-rules (else)
+             ((_ clause ...)))
+  (subsigs (clause
+            (pattern
+             (expr clause ...)
+             (else expression1 expression2 ...)))
+           (expr (or (lambda () *) #f)))
+  (desc "
+* It is an error if `expr` does not evaluate to a thunk or to `#f`.
+
+If `expr` evaluates to a thunk, then the thunk is tail-called as the
+result of the expression. Otherwise the macro evalates the next clause. If
+the `else` clause is reached, the expressions in the clause are evaluated
+as the result of the expression. If there is no `else` clause and all
+`expr` fail, then `cond-thunk` returns #f."))
+ ((name . "any-thunk")
+  (signature case-lambda
+             ((list? thunks) *)
+             ((list? thunks) (procedure? else-thunk) *))
+  (desc "
+* It is an error if `thunks` is not a proper list of thunks that return
+  either `#f` or another thunk.
+* It is an error if `else-thunk` isnot a thunk.
+
+This function is a procedural version of `cond-thunk`.
+
+Evaluate each `thunk` in `thunks` in order. If the `thunk` evaluates to
+a thunk, the thunk is tail-called. Otherwise evaluate the next thunk in
+the list.
+
+If all `thunks` evaluate to `#f`, then `else-thunk` is tail called. If
+`else-thunk` is not supplied, the function returns `#f`."))
+ ((name . "when-ct")
+  (signature syntax-rules ((_ conditional body ...)))
+  (desc "
+* It is an error if `formal` is not a lambda formal.
+* It is an error if `conditional` is not an expression.
+
+If `conditional` is true, return a thunk that when called executes
+`body ...`. Otherwise return `#f`."))
+ ((name . "lambda-ct")
+  (signature syntax-rules ((_ formal conditional body ...)))
+  (desc "
+* It is an error if `formal` is not a lambda formal.
+* It is an error if `conditional` is not an expression.
+
+Create a closure with arguments `formal` that evaluates `conditional`.
+If `conditional` returns a truthy value, a thunk closure with
+`body ...` as its body is returned. Otherwise the closure returns `#f`."))
+ (name . "define-ct")
+ (signature syntax-rules ((_ (name . formal) conditional body ...)))
+ (desc "
+* It is an error if `formal` is not a lambda formal.
+* It is an error if `conditional` is not an expression.
+
+Define a procedure `name` as a conditional generating a thunk. See
+`lambda-ct` for more details."))
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