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Word

Status: Experimental

present and registered, but lightly documented and not yet covered by dedicated tests.

Description

Word

is a type specification in Read and ReadList that reads a sequence of characters delimited by word separators (see WordSeparators).

Examples (4)

Every input below was run against the current Mathilda build and its output recorded.

Applications (4)

A bare read-type token, not a function

In[1]:= Head[Word]
Out[1]= Symbol

In[2]:= str = OpenWrite["/tmp/mathilda_word.txt"]; WriteString[str, "alpha beta gamma\n"]; Close[str];

Each whitespace-delimited run as a string

In[3]:= ReadList["/tmp/mathilda_word.txt", Word]
Out[3]= {"alpha", "beta", "gamma"}

Just the first word

In[4]:= ins = OpenRead["/tmp/mathilda_word.txt"]; w = Read[ins, Word]; Close[ins]; w
Out[4]= "alpha"

Implementation notes

Definition. Word is a read type token for Read and ReadList: it asks the reader to return the next run of characters delimited by word separators as a string. It is a bare symbol, not a function — no builtin, no DownValues, not even the Protected attribute — carrying only the docstring set in info_init (src/info.c). Its meaning lives in the reader src/io/read.c, where read_type_of maps the symbol SYM_Word to the internal RT_WORD case.

Representation. Word stays an inert EXPR_SYMBOL; evaluated on its own it is just Word, and Head[Word] is Symbol. It appears only as a type argument, e.g. Read[stream, Word] or ReadList["file", Word], and inside the type structure of a nested read such as ReadList["file", {Word, Number}].

Usage & limits. When the reader hits a Word slot it skips leading word separators (by default space and tab, configurable through WordSeparators), then collects characters up to the next separator and returns them as a String. TokenWords can force specific strings to read as standalone words, and NullWords -> True keeps empty fields between adjacent separators. A Word read past end of file returns EndOfFile. Word is distinct from Record (a whole record up to a record separator) and String (a line).

Attributes: none registered.

References

Notes & additional examples

Notes

Word is a read type for Read and ReadList: it reads the next run of characters delimited by word separators and returns it as a string. It is an inert token symbol — no builtin, no DownValues — recognised by the reader in src/io/read.c, which maps it to its internal word case.

ReadList["file", Word] returns every word as a flat list of strings; Read[stream, Word] returns just the next one and advances the stream. The separators default to space and tab and are set by WordSeparators; TokenWords forces given strings to read as standalone words, and NullWords -> True keeps empty fields between adjacent separators. A Word read past end of file returns EndOfFile.