Strings and Interpolation

Strings use single quotes, only. There is no double-quote form — one way to write a string, no style debates. Escape a quote with \':

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msg = 'he said \'hi\''
log[msg]

he said 'hi'

Interpolation

Any expression between paired backticks is evaluated into the string:

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name = 'crow'
n = 4
log['hello, `name`']
log['`n` squared is `n * n`']

hello, crow
4 squared is 16

Outside backticks, strings are completely inert — braces, JSON, and regex punctuation need no escaping. For a literal backtick, write \` . A backslash before any other character stays as it is, so a regular expression is written as it is: '\d+', '\|'.

Length and slicing count characters

len[], slice[], and indexing all work in characters, never bytes, so accented letters and dashes are one step each in both execution modes:

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s = 'naïve — café'
log[len[s]]
log[slice[s, 6, 7]]
log[s[-1]]
log[s[2]]

12
—
é
ï

Counting and mapping characters

occurs counts how many times a part occurs, not overlapping (as Python's str.count counts), and translate maps each character of one text to the character at its place in another, all in one pass — the complement of a strand of DNA:

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dna = 'GATTACA'
log[occurs[dna, 'A']]
log[occurs['aaaa', 'aa']]
log[translate[dna, 'ACGT', 'TGCA']]

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CTAATGT

No + on strings

+ is for numbers. To combine strings, interpolate; to build from many pieces, collect and join:

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parts = split['a,b,c', ',']
log[parts]
log[join[parts, '-']]
log[upper['crow']]

['a', 'b', 'c']
a-b-c
CROW

s = 'a' + 'b'    --- error: cannot use '+' with strings

The error message itself tells you the two idioms above. For value formatting (decimals, widths, percents) there's fmt[...] with named arguments — chapter 10 uses it heavily.